| /* |
| * Generic process-grouping system. |
| * |
| * Based originally on the cpuset system, extracted by Paul Menage |
| * Copyright (C) 2006 Google, Inc |
| * |
| * Notifications support |
| * Copyright (C) 2009 Nokia Corporation |
| * Author: Kirill A. Shutemov |
| * |
| * Copyright notices from the original cpuset code: |
| * -------------------------------------------------- |
| * Copyright (C) 2003 BULL SA. |
| * Copyright (C) 2004-2006 Silicon Graphics, Inc. |
| * |
| * Portions derived from Patrick Mochel's sysfs code. |
| * sysfs is Copyright (c) 2001-3 Patrick Mochel |
| * |
| * 2003-10-10 Written by Simon Derr. |
| * 2003-10-22 Updates by Stephen Hemminger. |
| * 2004 May-July Rework by Paul Jackson. |
| * --------------------------------------------------- |
| * |
| * This file is subject to the terms and conditions of the GNU General Public |
| * License. See the file COPYING in the main directory of the Linux |
| * distribution for more details. |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include "cgroup-internal.h" |
| |
| #include <linux/cred.h> |
| #include <linux/errno.h> |
| #include <linux/init_task.h> |
| #include <linux/kernel.h> |
| #include <linux/magic.h> |
| #include <linux/mutex.h> |
| #include <linux/mount.h> |
| #include <linux/pagemap.h> |
| #include <linux/proc_fs.h> |
| #include <linux/rcupdate.h> |
| #include <linux/sched.h> |
| #include <linux/sched/task.h> |
| #include <linux/slab.h> |
| #include <linux/spinlock.h> |
| #include <linux/percpu-rwsem.h> |
| #include <linux/string.h> |
| #include <linux/hashtable.h> |
| #include <linux/idr.h> |
| #include <linux/kthread.h> |
| #include <linux/atomic.h> |
| #include <linux/cpuset.h> |
| #include <linux/proc_ns.h> |
| #include <linux/nsproxy.h> |
| #include <linux/file.h> |
| #include <linux/fs_parser.h> |
| #include <linux/sched/cputime.h> |
| #include <linux/psi.h> |
| #include <net/sock.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/cgroup.h> |
| |
| #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \ |
| MAX_CFTYPE_NAME + 2) |
| /* let's not notify more than 100 times per second */ |
| #define CGROUP_FILE_NOTIFY_MIN_INTV DIV_ROUND_UP(HZ, 100) |
| |
| /* |
| * cgroup_mutex is the master lock. Any modification to cgroup or its |
| * hierarchy must be performed while holding it. |
| * |
| * css_set_lock protects task->cgroups pointer, the list of css_set |
| * objects, and the chain of tasks off each css_set. |
| * |
| * These locks are exported if CONFIG_PROVE_RCU so that accessors in |
| * cgroup.h can use them for lockdep annotations. |
| */ |
| DEFINE_MUTEX(cgroup_mutex); |
| DEFINE_SPINLOCK(css_set_lock); |
| |
| #ifdef CONFIG_PROVE_RCU |
| EXPORT_SYMBOL_GPL(cgroup_mutex); |
| EXPORT_SYMBOL_GPL(css_set_lock); |
| #endif |
| |
| DEFINE_SPINLOCK(trace_cgroup_path_lock); |
| char trace_cgroup_path[TRACE_CGROUP_PATH_LEN]; |
| bool cgroup_debug __read_mostly; |
| |
| /* |
| * Protects cgroup_idr and css_idr so that IDs can be released without |
| * grabbing cgroup_mutex. |
| */ |
| static DEFINE_SPINLOCK(cgroup_idr_lock); |
| |
| /* |
| * Protects cgroup_file->kn for !self csses. It synchronizes notifications |
| * against file removal/re-creation across css hiding. |
| */ |
| static DEFINE_SPINLOCK(cgroup_file_kn_lock); |
| |
| DEFINE_PERCPU_RWSEM(cgroup_threadgroup_rwsem); |
| |
| #define cgroup_assert_mutex_or_rcu_locked() \ |
| RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
| !lockdep_is_held(&cgroup_mutex), \ |
| "cgroup_mutex or RCU read lock required"); |
| |
| /* |
| * cgroup destruction makes heavy use of work items and there can be a lot |
| * of concurrent destructions. Use a separate workqueue so that cgroup |
| * destruction work items don't end up filling up max_active of system_wq |
| * which may lead to deadlock. |
| */ |
| static struct workqueue_struct *cgroup_destroy_wq; |
| |
| /* generate an array of cgroup subsystem pointers */ |
| #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys, |
| struct cgroup_subsys *cgroup_subsys[] = { |
| #include <linux/cgroup_subsys.h> |
| }; |
| #undef SUBSYS |
| |
| /* array of cgroup subsystem names */ |
| #define SUBSYS(_x) [_x ## _cgrp_id] = #_x, |
| static const char *cgroup_subsys_name[] = { |
| #include <linux/cgroup_subsys.h> |
| }; |
| #undef SUBSYS |
| |
| /* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */ |
| #define SUBSYS(_x) \ |
| DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \ |
| DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \ |
| EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \ |
| EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key); |
| #include <linux/cgroup_subsys.h> |
| #undef SUBSYS |
| |
| #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key, |
| static struct static_key_true *cgroup_subsys_enabled_key[] = { |
| #include <linux/cgroup_subsys.h> |
| }; |
| #undef SUBSYS |
| |
| #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key, |
| static struct static_key_true *cgroup_subsys_on_dfl_key[] = { |
| #include <linux/cgroup_subsys.h> |
| }; |
| #undef SUBSYS |
| |
| static DEFINE_PER_CPU(struct cgroup_rstat_cpu, cgrp_dfl_root_rstat_cpu); |
| |
| /* |
| * The default hierarchy, reserved for the subsystems that are otherwise |
| * unattached - it never has more than a single cgroup, and all tasks are |
| * part of that cgroup. |
| */ |
| struct cgroup_root cgrp_dfl_root = { .cgrp.rstat_cpu = &cgrp_dfl_root_rstat_cpu }; |
| EXPORT_SYMBOL_GPL(cgrp_dfl_root); |
| |
| /* |
| * The default hierarchy always exists but is hidden until mounted for the |
| * first time. This is for backward compatibility. |
| */ |
| static bool cgrp_dfl_visible; |
| |
| /* some controllers are not supported in the default hierarchy */ |
| static u16 cgrp_dfl_inhibit_ss_mask; |
| |
| /* some controllers are implicitly enabled on the default hierarchy */ |
| static u16 cgrp_dfl_implicit_ss_mask; |
| |
| /* some controllers can be threaded on the default hierarchy */ |
| static u16 cgrp_dfl_threaded_ss_mask; |
| |
| /* The list of hierarchy roots */ |
| LIST_HEAD(cgroup_roots); |
| static int cgroup_root_count; |
| |
| /* hierarchy ID allocation and mapping, protected by cgroup_mutex */ |
| static DEFINE_IDR(cgroup_hierarchy_idr); |
| |
| /* |
| * Assign a monotonically increasing serial number to csses. It guarantees |
| * cgroups with bigger numbers are newer than those with smaller numbers. |
| * Also, as csses are always appended to the parent's ->children list, it |
| * guarantees that sibling csses are always sorted in the ascending serial |
| * number order on the list. Protected by cgroup_mutex. |
| */ |
| static u64 css_serial_nr_next = 1; |
| |
| /* |
| * These bitmasks identify subsystems with specific features to avoid |
| * having to do iterative checks repeatedly. |
| */ |
| static u16 have_fork_callback __read_mostly; |
| static u16 have_exit_callback __read_mostly; |
| static u16 have_release_callback __read_mostly; |
| static u16 have_canfork_callback __read_mostly; |
| |
| /* cgroup namespace for init task */ |
| struct cgroup_namespace init_cgroup_ns = { |
| .count = REFCOUNT_INIT(2), |
| .user_ns = &init_user_ns, |
| .ns.ops = &cgroupns_operations, |
| .ns.inum = PROC_CGROUP_INIT_INO, |
| .root_cset = &init_css_set, |
| }; |
| |
| static struct file_system_type cgroup2_fs_type; |
| static struct cftype cgroup_base_files[]; |
| |
| static int cgroup_apply_control(struct cgroup *cgrp); |
| static void cgroup_finalize_control(struct cgroup *cgrp, int ret); |
| static void css_task_iter_skip(struct css_task_iter *it, |
| struct task_struct *task); |
| static int cgroup_destroy_locked(struct cgroup *cgrp); |
| static struct cgroup_subsys_state *css_create(struct cgroup *cgrp, |
| struct cgroup_subsys *ss); |
| static void css_release(struct percpu_ref *ref); |
| static void kill_css(struct cgroup_subsys_state *css); |
| static int cgroup_addrm_files(struct cgroup_subsys_state *css, |
| struct cgroup *cgrp, struct cftype cfts[], |
| bool is_add); |
| |
| /** |
| * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID |
| * @ssid: subsys ID of interest |
| * |
| * cgroup_subsys_enabled() can only be used with literal subsys names which |
| * is fine for individual subsystems but unsuitable for cgroup core. This |
| * is slower static_key_enabled() based test indexed by @ssid. |
| */ |
| bool cgroup_ssid_enabled(int ssid) |
| { |
| if (CGROUP_SUBSYS_COUNT == 0) |
| return false; |
| |
| return static_key_enabled(cgroup_subsys_enabled_key[ssid]); |
| } |
| |
| /** |
| * cgroup_on_dfl - test whether a cgroup is on the default hierarchy |
| * @cgrp: the cgroup of interest |
| * |
| * The default hierarchy is the v2 interface of cgroup and this function |
| * can be used to test whether a cgroup is on the default hierarchy for |
| * cases where a subsystem should behave differnetly depending on the |
| * interface version. |
| * |
| * The set of behaviors which change on the default hierarchy are still |
| * being determined and the mount option is prefixed with __DEVEL__. |
| * |
| * List of changed behaviors: |
| * |
| * - Mount options "noprefix", "xattr", "clone_children", "release_agent" |
| * and "name" are disallowed. |
| * |
| * - When mounting an existing superblock, mount options should match. |
| * |
| * - Remount is disallowed. |
| * |
| * - rename(2) is disallowed. |
| * |
| * - "tasks" is removed. Everything should be at process granularity. Use |
| * "cgroup.procs" instead. |
| * |
| * - "cgroup.procs" is not sorted. pids will be unique unless they got |
| * recycled inbetween reads. |
| * |
| * - "release_agent" and "notify_on_release" are removed. Replacement |
| * notification mechanism will be implemented. |
| * |
| * - "cgroup.clone_children" is removed. |
| * |
| * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup |
| * and its descendants contain no task; otherwise, 1. The file also |
| * generates kernfs notification which can be monitored through poll and |
| * [di]notify when the value of the file changes. |
| * |
| * - cpuset: tasks will be kept in empty cpusets when hotplug happens and |
| * take masks of ancestors with non-empty cpus/mems, instead of being |
| * moved to an ancestor. |
| * |
| * - cpuset: a task can be moved into an empty cpuset, and again it takes |
| * masks of ancestors. |
| * |
| * - memcg: use_hierarchy is on by default and the cgroup file for the flag |
| * is not created. |
| * |
| * - blkcg: blk-throttle becomes properly hierarchical. |
| * |
| * - debug: disallowed on the default hierarchy. |
| */ |
| bool cgroup_on_dfl(const struct cgroup *cgrp) |
| { |
| return cgrp->root == &cgrp_dfl_root; |
| } |
| |
| /* IDR wrappers which synchronize using cgroup_idr_lock */ |
| static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end, |
| gfp_t gfp_mask) |
| { |
| int ret; |
| |
| idr_preload(gfp_mask); |
| spin_lock_bh(&cgroup_idr_lock); |
| ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM); |
| spin_unlock_bh(&cgroup_idr_lock); |
| idr_preload_end(); |
| return ret; |
| } |
| |
| static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id) |
| { |
| void *ret; |
| |
| spin_lock_bh(&cgroup_idr_lock); |
| ret = idr_replace(idr, ptr, id); |
| spin_unlock_bh(&cgroup_idr_lock); |
| return ret; |
| } |
| |
| static void cgroup_idr_remove(struct idr *idr, int id) |
| { |
| spin_lock_bh(&cgroup_idr_lock); |
| idr_remove(idr, id); |
| spin_unlock_bh(&cgroup_idr_lock); |
| } |
| |
| static bool cgroup_has_tasks(struct cgroup *cgrp) |
| { |
| return cgrp->nr_populated_csets; |
| } |
| |
| bool cgroup_is_threaded(struct cgroup *cgrp) |
| { |
| return cgrp->dom_cgrp != cgrp; |
| } |
| |
| /* can @cgrp host both domain and threaded children? */ |
| static bool cgroup_is_mixable(struct cgroup *cgrp) |
| { |
| /* |
| * Root isn't under domain level resource control exempting it from |
| * the no-internal-process constraint, so it can serve as a thread |
| * root and a parent of resource domains at the same time. |
| */ |
| return !cgroup_parent(cgrp); |
| } |
| |
| /* can @cgrp become a thread root? should always be true for a thread root */ |
| static bool cgroup_can_be_thread_root(struct cgroup *cgrp) |
| { |
| /* mixables don't care */ |
| if (cgroup_is_mixable(cgrp)) |
| return true; |
| |
| /* domain roots can't be nested under threaded */ |
| if (cgroup_is_threaded(cgrp)) |
| return false; |
| |
| /* can only have either domain or threaded children */ |
| if (cgrp->nr_populated_domain_children) |
| return false; |
| |
| /* and no domain controllers can be enabled */ |
| if (cgrp->subtree_control & ~cgrp_dfl_threaded_ss_mask) |
| return false; |
| |
| return true; |
| } |
| |
| /* is @cgrp root of a threaded subtree? */ |
| bool cgroup_is_thread_root(struct cgroup *cgrp) |
| { |
| /* thread root should be a domain */ |
| if (cgroup_is_threaded(cgrp)) |
| return false; |
| |
| /* a domain w/ threaded children is a thread root */ |
| if (cgrp->nr_threaded_children) |
| return true; |
| |
| /* |
| * A domain which has tasks and explicit threaded controllers |
| * enabled is a thread root. |
| */ |
| if (cgroup_has_tasks(cgrp) && |
| (cgrp->subtree_control & cgrp_dfl_threaded_ss_mask)) |
| return true; |
| |
| return false; |
| } |
| |
| /* a domain which isn't connected to the root w/o brekage can't be used */ |
| static bool cgroup_is_valid_domain(struct cgroup *cgrp) |
| { |
| /* the cgroup itself can be a thread root */ |
| if (cgroup_is_threaded(cgrp)) |
| return false; |
| |
| /* but the ancestors can't be unless mixable */ |
| while ((cgrp = cgroup_parent(cgrp))) { |
| if (!cgroup_is_mixable(cgrp) && cgroup_is_thread_root(cgrp)) |
| return false; |
| if (cgroup_is_threaded(cgrp)) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| /* subsystems visibly enabled on a cgroup */ |
| static u16 cgroup_control(struct cgroup *cgrp) |
| { |
| struct cgroup *parent = cgroup_parent(cgrp); |
| u16 root_ss_mask = cgrp->root->subsys_mask; |
| |
| if (parent) { |
| u16 ss_mask = parent->subtree_control; |
| |
| /* threaded cgroups can only have threaded controllers */ |
| if (cgroup_is_threaded(cgrp)) |
| ss_mask &= cgrp_dfl_threaded_ss_mask; |
| return ss_mask; |
| } |
| |
| if (cgroup_on_dfl(cgrp)) |
| root_ss_mask &= ~(cgrp_dfl_inhibit_ss_mask | |
| cgrp_dfl_implicit_ss_mask); |
| return root_ss_mask; |
| } |
| |
| /* subsystems enabled on a cgroup */ |
| static u16 cgroup_ss_mask(struct cgroup *cgrp) |
| { |
| struct cgroup *parent = cgroup_parent(cgrp); |
| |
| if (parent) { |
| u16 ss_mask = parent->subtree_ss_mask; |
| |
| /* threaded cgroups can only have threaded controllers */ |
| if (cgroup_is_threaded(cgrp)) |
| ss_mask &= cgrp_dfl_threaded_ss_mask; |
| return ss_mask; |
| } |
| |
| return cgrp->root->subsys_mask; |
| } |
| |
| /** |
| * cgroup_css - obtain a cgroup's css for the specified subsystem |
| * @cgrp: the cgroup of interest |
| * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
| * |
| * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This |
| * function must be called either under cgroup_mutex or rcu_read_lock() and |
| * the caller is responsible for pinning the returned css if it wants to |
| * keep accessing it outside the said locks. This function may return |
| * %NULL if @cgrp doesn't have @subsys_id enabled. |
| */ |
| static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, |
| struct cgroup_subsys *ss) |
| { |
| if (ss) |
| return rcu_dereference_check(cgrp->subsys[ss->id], |
| lockdep_is_held(&cgroup_mutex)); |
| else |
| return &cgrp->self; |
| } |
| |
| /** |
| * cgroup_tryget_css - try to get a cgroup's css for the specified subsystem |
| * @cgrp: the cgroup of interest |
| * @ss: the subsystem of interest |
| * |
| * Find and get @cgrp's css assocaited with @ss. If the css doesn't exist |
| * or is offline, %NULL is returned. |
| */ |
| static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp, |
| struct cgroup_subsys *ss) |
| { |
| struct cgroup_subsys_state *css; |
| |
| rcu_read_lock(); |
| css = cgroup_css(cgrp, ss); |
| if (!css || !css_tryget_online(css)) |
| css = NULL; |
| rcu_read_unlock(); |
| |
| return css; |
| } |
| |
| /** |
| * cgroup_e_css_by_mask - obtain a cgroup's effective css for the specified ss |
| * @cgrp: the cgroup of interest |
| * @ss: the subsystem of interest (%NULL returns @cgrp->self) |
| * |
| * Similar to cgroup_css() but returns the effective css, which is defined |
| * as the matching css of the nearest ancestor including self which has @ss |
| * enabled. If @ss is associated with the hierarchy @cgrp is on, this |
| * function is guaranteed to return non-NULL css. |
| */ |
| static struct cgroup_subsys_state *cgroup_e_css_by_mask(struct cgroup *cgrp, |
| struct cgroup_subsys *ss) |
| { |
| lockdep_assert_held(&cgroup_mutex); |
| |
| if (!ss) |
| return &cgrp->self; |
| |
| /* |
| * This function is used while updating css associations and thus |
| * can't test the csses directly. Test ss_mask. |
| */ |
| while (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) { |
| cgrp = cgroup_parent(cgrp); |
| if (!cgrp) |
| return NULL; |
| } |
| |
| return cgroup_css(cgrp, ss); |
| } |
| |
| /** |
| * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem |
| * @cgrp: the cgroup of interest |
| * @ss: the subsystem of interest |
| * |
| * Find and get the effective css of @cgrp for @ss. The effective css is |
| * defined as the matching css of the nearest ancestor including self which |
| * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on, |
| * the root css is returned, so this function always returns a valid css. |
| * |
| * The returned css is not guaranteed to be online, and therefore it is the |
| * callers responsiblity to tryget a reference for it. |
| */ |
| struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp, |
| struct cgroup_subsys *ss) |
| { |
| struct cgroup_subsys_state *css; |
| |
| do { |
| css = cgroup_css(cgrp, ss); |
| |
| if (css) |
| return css; |
| cgrp = cgroup_parent(cgrp); |
| } while (cgrp); |
| |
| return init_css_set.subsys[ss->id]; |
| } |
| |
| /** |
| * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem |
| * @cgrp: the cgroup of interest |
| * @ss: the subsystem of interest |
| * |
| * Find and get the effective css of @cgrp for @ss. The effective css is |
| * defined as the matching css of the nearest ancestor including self which |
| * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on, |
| * the root css is returned, so this function always returns a valid css. |
| * The returned css must be put using css_put(). |
| */ |
| struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp, |
| struct cgroup_subsys *ss) |
| { |
| struct cgroup_subsys_state *css; |
| |
| rcu_read_lock(); |
| |
| do { |
| css = cgroup_css(cgrp, ss); |
| |
| if (css && css_tryget_online(css)) |
| goto out_unlock; |
| cgrp = cgroup_parent(cgrp); |
| } while (cgrp); |
| |
| css = init_css_set.subsys[ss->id]; |
| css_get(css); |
| out_unlock: |
| rcu_read_unlock(); |
| return css; |
| } |
| |
| static void cgroup_get_live(struct cgroup *cgrp) |
| { |
| WARN_ON_ONCE(cgroup_is_dead(cgrp)); |
| css_get(&cgrp->self); |
| } |
| |
| /** |
| * __cgroup_task_count - count the number of tasks in a cgroup. The caller |
| * is responsible for taking the css_set_lock. |
| * @cgrp: the cgroup in question |
| */ |
| int __cgroup_task_count(const struct cgroup *cgrp) |
| { |
| int count = 0; |
| struct cgrp_cset_link *link; |
| |
| lockdep_assert_held(&css_set_lock); |
| |
| list_for_each_entry(link, &cgrp->cset_links, cset_link) |
| count += link->cset->nr_tasks; |
| |
| return count; |
| } |
| |
| /** |
| * cgroup_task_count - count the number of tasks in a cgroup. |
| * @cgrp: the cgroup in question |
| */ |
| int cgroup_task_count(const struct cgroup *cgrp) |
| { |
| int count; |
| |
| spin_lock_irq(&css_set_lock); |
| count = __cgroup_task_count(cgrp); |
| spin_unlock_irq(&css_set_lock); |
| |
| return count; |
| } |
| |
| struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) |
| { |
| struct cgroup *cgrp = of->kn->parent->priv; |
| struct cftype *cft = of_cft(of); |
| |
| /* |
| * This is open and unprotected implementation of cgroup_css(). |
| * seq_css() is only called from a kernfs file operation which has |
| * an active reference on the file. Because all the subsystem |
| * files are drained before a css is disassociated with a cgroup, |
| * the matching css from the cgroup's subsys table is guaranteed to |
| * be and stay valid until the enclosing operation is complete. |
| */ |
| if (cft->ss) |
| return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); |
| else |
| return &cgrp->self; |
| } |
| EXPORT_SYMBOL_GPL(of_css); |
| |
| /** |
| * for_each_css - iterate all css's of a cgroup |
| * @css: the iteration cursor |
| * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end |
| * @cgrp: the target cgroup to iterate css's of |
| * |
| * Should be called under cgroup_[tree_]mutex. |
| */ |
| #define for_each_css(css, ssid, cgrp) \ |
| for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ |
| if (!((css) = rcu_dereference_check( \ |
| (cgrp)->subsys[(ssid)], \ |
| lockdep_is_held(&cgroup_mutex)))) { } \ |
| else |
| |
| /** |
| * for_each_e_css - iterate all effective css's of a cgroup |
| * @css: the iteration cursor |
| * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end |
| * @cgrp: the target cgroup to iterate css's of |
| * |
| * Should be called under cgroup_[tree_]mutex. |
| */ |
| #define for_each_e_css(css, ssid, cgrp) \ |
| for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ |
| if (!((css) = cgroup_e_css_by_mask(cgrp, \ |
| cgroup_subsys[(ssid)]))) \ |
| ; \ |
| else |
| |
| /** |
| * do_each_subsys_mask - filter for_each_subsys with a bitmask |
| * @ss: the iteration cursor |
| * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
| * @ss_mask: the bitmask |
| * |
| * The block will only run for cases where the ssid-th bit (1 << ssid) of |
| * @ss_mask is set. |
| */ |
| #define do_each_subsys_mask(ss, ssid, ss_mask) do { \ |
| unsigned long __ss_mask = (ss_mask); \ |
| if (!CGROUP_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \ |
| (ssid) = 0; \ |
| break; \ |
| } \ |
| for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \ |
| (ss) = cgroup_subsys[ssid]; \ |
| { |
| |
| #define while_each_subsys_mask() \ |
| } \ |
| } \ |
| } while (false) |
| |
| /* iterate over child cgrps, lock should be held throughout iteration */ |
| #define cgroup_for_each_live_child(child, cgrp) \ |
| list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \ |
| if (({ lockdep_assert_held(&cgroup_mutex); \ |
| cgroup_is_dead(child); })) \ |
| ; \ |
| else |
| |
| /* walk live descendants in preorder */ |
| #define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) \ |
| css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL)) \ |
| if (({ lockdep_assert_held(&cgroup_mutex); \ |
| (dsct) = (d_css)->cgroup; \ |
| cgroup_is_dead(dsct); })) \ |
| ; \ |
| else |
| |
| /* walk live descendants in postorder */ |
| #define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) \ |
| css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL)) \ |
| if (({ lockdep_assert_held(&cgroup_mutex); \ |
| (dsct) = (d_css)->cgroup; \ |
| cgroup_is_dead(dsct); })) \ |
| ; \ |
| else |
| |
| /* |
| * The default css_set - used by init and its children prior to any |
| * hierarchies being mounted. It contains a pointer to the root state |
| * for each subsystem. Also used to anchor the list of css_sets. Not |
| * reference-counted, to improve performance when child cgroups |
| * haven't been created. |
| */ |
| struct css_set init_css_set = { |
| .refcount = REFCOUNT_INIT(1), |
| .dom_cset = &init_css_set, |
| .tasks = LIST_HEAD_INIT(init_css_set.tasks), |
| .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks), |
| .dying_tasks = LIST_HEAD_INIT(init_css_set.dying_tasks), |
| .task_iters = LIST_HEAD_INIT(init_css_set.task_iters), |
| .threaded_csets = LIST_HEAD_INIT(init_css_set.threaded_csets), |
| .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links), |
| .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node), |
| .mg_node = LIST_HEAD_INIT(init_css_set.mg_node), |
| |
| /* |
| * The following field is re-initialized when this cset gets linked |
| * in cgroup_init(). However, let's initialize the field |
| * statically too so that the default cgroup can be accessed safely |
| * early during boot. |
| */ |
| .dfl_cgrp = &cgrp_dfl_root.cgrp, |
| }; |
| |
| static int css_set_count = 1; /* 1 for init_css_set */ |
| |
| static bool css_set_threaded(struct css_set *cset) |
| { |
| return cset->dom_cset != cset; |
| } |
| |
| /** |
| * css_set_populated - does a css_set contain any tasks? |
| * @cset: target css_set |
| * |
| * css_set_populated() should be the same as !!cset->nr_tasks at steady |
| * state. However, css_set_populated() can be called while a task is being |
| * added to or removed from the linked list before the nr_tasks is |
| * properly updated. Hence, we can't just look at ->nr_tasks here. |
| */ |
| static bool css_set_populated(struct css_set *cset) |
| { |
| lockdep_assert_held(&css_set_lock); |
| |
| return !list_empty(&cset->tasks) || !list_empty(&cset->mg_tasks); |
| } |
| |
| /** |
| * cgroup_update_populated - update the populated count of a cgroup |
| * @cgrp: the target cgroup |
| * @populated: inc or dec populated count |
| * |
| * One of the css_sets associated with @cgrp is either getting its first |
| * task or losing the last. Update @cgrp->nr_populated_* accordingly. The |
| * count is propagated towards root so that a given cgroup's |
| * nr_populated_children is zero iff none of its descendants contain any |
| * tasks. |
| * |
| * @cgrp's interface file "cgroup.populated" is zero if both |
| * @cgrp->nr_populated_csets and @cgrp->nr_populated_children are zero and |
| * 1 otherwise. When the sum changes from or to zero, userland is notified |
| * that the content of the interface file has changed. This can be used to |
| * detect when @cgrp and its descendants become populated or empty. |
| */ |
| static void cgroup_update_populated(struct cgroup *cgrp, bool populated) |
| { |
| struct cgroup *child = NULL; |
| int adj = populated ? 1 : -1; |
| |
| lockdep_assert_held(&css_set_lock); |
| |
| do { |
| bool was_populated = cgroup_is_populated(cgrp); |
| |
| if (!child) { |
| cgrp->nr_populated_csets += adj; |
| } else { |
| if (cgroup_is_threaded(child)) |
| cgrp->nr_populated_threaded_children += adj; |
| else |
| cgrp->nr_populated_domain_children += adj; |
| } |
| |
| if (was_populated == cgroup_is_populated(cgrp)) |
| break; |
| |
| cgroup1_check_for_release(cgrp); |
| TRACE_CGROUP_PATH(notify_populated, cgrp, |
| cgroup_is_populated(cgrp)); |
| cgroup_file_notify(&cgrp->events_file); |
| |
| child = cgrp; |
| cgrp = cgroup_parent(cgrp); |
| } while (cgrp); |
| } |
| |
| /** |
| * css_set_update_populated - update populated state of a css_set |
| * @cset: target css_set |
| * @populated: whether @cset is populated or depopulated |
| * |
| * @cset is either getting the first task or losing the last. Update the |
| * populated counters of all associated cgroups accordingly. |
| */ |
| static void css_set_update_populated(struct css_set *cset, bool populated) |
| { |
| struct cgrp_cset_link *link; |
| |
| lockdep_assert_held(&css_set_lock); |
| |
| list_for_each_entry(link, &cset->cgrp_links, cgrp_link) |
| cgroup_update_populated(link->cgrp, populated); |
| } |
| |
| /* |
| * @task is leaving, advance task iterators which are pointing to it so |
| * that they can resume at the next position. Advancing an iterator might |
| * remove it from the list, use safe walk. See css_task_iter_skip() for |
| * details. |
| */ |
| static void css_set_skip_task_iters(struct css_set *cset, |
| struct task_struct *task) |
| { |
| struct css_task_iter *it, *pos; |
| |
| list_for_each_entry_safe(it, pos, &cset->task_iters, iters_node) |
| css_task_iter_skip(it, task); |
| } |
| |
| /** |
| * css_set_move_task - move a task from one css_set to another |
| * @task: task being moved |
| * @from_cset: css_set @task currently belongs to (may be NULL) |
| * @to_cset: new css_set @task is being moved to (may be NULL) |
| * @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks |
| * |
| * Move @task from @from_cset to @to_cset. If @task didn't belong to any |
| * css_set, @from_cset can be NULL. If @task is being disassociated |
| * instead of moved, @to_cset can be NULL. |
| * |
| * This function automatically handles populated counter updates and |
| * css_task_iter adjustments but the caller is responsible for managing |
| * @from_cset and @to_cset's reference counts. |
| */ |
| static void css_set_move_task(struct task_struct *task, |
| struct css_set *from_cset, struct css_set *to_cset, |
| bool use_mg_tasks) |
| { |
| lockdep_assert_held(&css_set_lock); |
| |
| if (to_cset && !css_set_populated(to_cset)) |
| css_set_update_populated(to_cset, true); |
| |
| if (from_cset) { |
| WARN_ON_ONCE(list_empty(&task->cg_list)); |
| |
| css_set_skip_task_iters(from_cset, task); |
| list_del_init(&task->cg_list); |
| if (!css_set_populated(from_cset)) |
| css_set_update_populated(from_cset, false); |
| } else { |
| WARN_ON_ONCE(!list_empty(&task->cg_list)); |
| } |
| |
| if (to_cset) { |
| /* |
| * We are synchronized through cgroup_threadgroup_rwsem |
| * against PF_EXITING setting such that we can't race |
| * against cgroup_exit() changing the css_set to |
| * init_css_set and dropping the old one. |
| */ |
| WARN_ON_ONCE(task->flags & PF_EXITING); |
| |
| cgroup_move_task(task, to_cset); |
| list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks : |
| &to_cset->tasks); |
| } |
| } |
| |
| /* |
| * hash table for cgroup groups. This improves the performance to find |
| * an existing css_set. This hash doesn't (currently) take into |
| * account cgroups in empty hierarchies. |
| */ |
| #define CSS_SET_HASH_BITS 7 |
| static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
| |
| static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
| { |
| unsigned long key = 0UL; |
| struct cgroup_subsys *ss; |
| int i; |
| |
| for_each_subsys(ss, i) |
| key += (unsigned long)css[i]; |
| key = (key >> 16) ^ key; |
| |
| return key; |
| } |
| |
| void put_css_set_locked(struct css_set *cset) |
| { |
| struct cgrp_cset_link *link, *tmp_link; |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| lockdep_assert_held(&css_set_lock); |
| |
| if (!refcount_dec_and_test(&cset->refcount)) |
| return; |
| |
| WARN_ON_ONCE(!list_empty(&cset->threaded_csets)); |
| |
| /* This css_set is dead. unlink it and release cgroup and css refs */ |
| for_each_subsys(ss, ssid) { |
| list_del(&cset->e_cset_node[ssid]); |
| css_put(cset->subsys[ssid]); |
| } |
| hash_del(&cset->hlist); |
| css_set_count--; |
| |
| list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
| list_del(&link->cset_link); |
| list_del(&link->cgrp_link); |
| if (cgroup_parent(link->cgrp)) |
| cgroup_put(link->cgrp); |
| kfree(link); |
| } |
| |
| if (css_set_threaded(cset)) { |
| list_del(&cset->threaded_csets_node); |
| put_css_set_locked(cset->dom_cset); |
| } |
| |
| kfree_rcu(cset, rcu_head); |
| } |
| |
| /** |
| * compare_css_sets - helper function for find_existing_css_set(). |
| * @cset: candidate css_set being tested |
| * @old_cset: existing css_set for a task |
| * @new_cgrp: cgroup that's being entered by the task |
| * @template: desired set of css pointers in css_set (pre-calculated) |
| * |
| * Returns true if "cset" matches "old_cset" except for the hierarchy |
| * which "new_cgrp" belongs to, for which it should match "new_cgrp". |
| */ |
| static bool compare_css_sets(struct css_set *cset, |
| struct css_set *old_cset, |
| struct cgroup *new_cgrp, |
| struct cgroup_subsys_state *template[]) |
| { |
| struct cgroup *new_dfl_cgrp; |
| struct list_head *l1, *l2; |
| |
| /* |
| * On the default hierarchy, there can be csets which are |
| * associated with the same set of cgroups but different csses. |
| * Let's first ensure that csses match. |
| */ |
| if (memcmp(template, cset->subsys, sizeof(cset->subsys))) |
| return false; |
| |
| |
| /* @cset's domain should match the default cgroup's */ |
| if (cgroup_on_dfl(new_cgrp)) |
| new_dfl_cgrp = new_cgrp; |
| else |
| new_dfl_cgrp = old_cset->dfl_cgrp; |
| |
| if (new_dfl_cgrp->dom_cgrp != cset->dom_cset->dfl_cgrp) |
| return false; |
| |
| /* |
| * Compare cgroup pointers in order to distinguish between |
| * different cgroups in hierarchies. As different cgroups may |
| * share the same effective css, this comparison is always |
| * necessary. |
| */ |
| l1 = &cset->cgrp_links; |
| l2 = &old_cset->cgrp_links; |
| while (1) { |
| struct cgrp_cset_link *link1, *link2; |
| struct cgroup *cgrp1, *cgrp2; |
| |
| l1 = l1->next; |
| l2 = l2->next; |
| /* See if we reached the end - both lists are equal length. */ |
| if (l1 == &cset->cgrp_links) { |
| BUG_ON(l2 != &old_cset->cgrp_links); |
| break; |
| } else { |
| BUG_ON(l2 == &old_cset->cgrp_links); |
| } |
| /* Locate the cgroups associated with these links. */ |
| link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
| link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); |
| cgrp1 = link1->cgrp; |
| cgrp2 = link2->cgrp; |
| /* Hierarchies should be linked in the same order. */ |
| BUG_ON(cgrp1->root != cgrp2->root); |
| |
| /* |
| * If this hierarchy is the hierarchy of the cgroup |
| * that's changing, then we need to check that this |
| * css_set points to the new cgroup; if it's any other |
| * hierarchy, then this css_set should point to the |
| * same cgroup as the old css_set. |
| */ |
| if (cgrp1->root == new_cgrp->root) { |
| if (cgrp1 != new_cgrp) |
| return false; |
| } else { |
| if (cgrp1 != cgrp2) |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| /** |
| * find_existing_css_set - init css array and find the matching css_set |
| * @old_cset: the css_set that we're using before the cgroup transition |
| * @cgrp: the cgroup that we're moving into |
| * @template: out param for the new set of csses, should be clear on entry |
| */ |
| static struct css_set *find_existing_css_set(struct css_set *old_cset, |
| struct cgroup *cgrp, |
| struct cgroup_subsys_state *template[]) |
| { |
| struct cgroup_root *root = cgrp->root; |
| struct cgroup_subsys *ss; |
| struct css_set *cset; |
| unsigned long key; |
| int i; |
| |
| /* |
| * Build the set of subsystem state objects that we want to see in the |
| * new css_set. while subsystems can change globally, the entries here |
| * won't change, so no need for locking. |
| */ |
| for_each_subsys(ss, i) { |
| if (root->subsys_mask & (1UL << i)) { |
| /* |
| * @ss is in this hierarchy, so we want the |
| * effective css from @cgrp. |
| */ |
| template[i] = cgroup_e_css_by_mask(cgrp, ss); |
| } else { |
| /* |
| * @ss is not in this hierarchy, so we don't want |
| * to change the css. |
| */ |
| template[i] = old_cset->subsys[i]; |
| } |
| } |
| |
| key = css_set_hash(template); |
| hash_for_each_possible(css_set_table, cset, hlist, key) { |
| if (!compare_css_sets(cset, old_cset, cgrp, template)) |
| continue; |
| |
| /* This css_set matches what we need */ |
| return cset; |
| } |
| |
| /* No existing cgroup group matched */ |
| return NULL; |
| } |
| |
| static void free_cgrp_cset_links(struct list_head *links_to_free) |
| { |
| struct cgrp_cset_link *link, *tmp_link; |
| |
| list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
| list_del(&link->cset_link); |
| kfree(link); |
| } |
| } |
| |
| /** |
| * allocate_cgrp_cset_links - allocate cgrp_cset_links |
| * @count: the number of links to allocate |
| * @tmp_links: list_head the allocated links are put on |
| * |
| * Allocate @count cgrp_cset_link structures and chain them on @tmp_links |
| * through ->cset_link. Returns 0 on success or -errno. |
| */ |
| static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
| { |
| struct cgrp_cset_link *link; |
| int i; |
| |
| INIT_LIST_HEAD(tmp_links); |
| |
| for (i = 0; i < count; i++) { |
| link = kzalloc(sizeof(*link), GFP_KERNEL); |
| if (!link) { |
| free_cgrp_cset_links(tmp_links); |
| return -ENOMEM; |
| } |
| list_add(&link->cset_link, tmp_links); |
| } |
| return 0; |
| } |
| |
| /** |
| * link_css_set - a helper function to link a css_set to a cgroup |
| * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
| * @cset: the css_set to be linked |
| * @cgrp: the destination cgroup |
| */ |
| static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
| struct cgroup *cgrp) |
| { |
| struct cgrp_cset_link *link; |
| |
| BUG_ON(list_empty(tmp_links)); |
| |
| if (cgroup_on_dfl(cgrp)) |
| cset->dfl_cgrp = cgrp; |
| |
| link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); |
| link->cset = cset; |
| link->cgrp = cgrp; |
| |
| /* |
| * Always add links to the tail of the lists so that the lists are |
| * in choronological order. |
| */ |
| list_move_tail(&link->cset_link, &cgrp->cset_links); |
| list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
| |
| if (cgroup_parent(cgrp)) |
| cgroup_get_live(cgrp); |
| } |
| |
| /** |
| * find_css_set - return a new css_set with one cgroup updated |
| * @old_cset: the baseline css_set |
| * @cgrp: the cgroup to be updated |
| * |
| * Return a new css_set that's equivalent to @old_cset, but with @cgrp |
| * substituted into the appropriate hierarchy. |
| */ |
| static struct css_set *find_css_set(struct css_set *old_cset, |
| struct cgroup *cgrp) |
| { |
| struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; |
| struct css_set *cset; |
| struct list_head tmp_links; |
| struct cgrp_cset_link *link; |
| struct cgroup_subsys *ss; |
| unsigned long key; |
| int ssid; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| /* First see if we already have a cgroup group that matches |
| * the desired set */ |
| spin_lock_irq(&css_set_lock); |
| cset = find_existing_css_set(old_cset, cgrp, template); |
| if (cset) |
| get_css_set(cset); |
| spin_unlock_irq(&css_set_lock); |
| |
| if (cset) |
| return cset; |
| |
| cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
| if (!cset) |
| return NULL; |
| |
| /* Allocate all the cgrp_cset_link objects that we'll need */ |
| if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { |
| kfree(cset); |
| return NULL; |
| } |
| |
| refcount_set(&cset->refcount, 1); |
| cset->dom_cset = cset; |
| INIT_LIST_HEAD(&cset->tasks); |
| INIT_LIST_HEAD(&cset->mg_tasks); |
| INIT_LIST_HEAD(&cset->dying_tasks); |
| INIT_LIST_HEAD(&cset->task_iters); |
| INIT_LIST_HEAD(&cset->threaded_csets); |
| INIT_HLIST_NODE(&cset->hlist); |
| INIT_LIST_HEAD(&cset->cgrp_links); |
| INIT_LIST_HEAD(&cset->mg_preload_node); |
| INIT_LIST_HEAD(&cset->mg_node); |
| |
| /* Copy the set of subsystem state objects generated in |
| * find_existing_css_set() */ |
| memcpy(cset->subsys, template, sizeof(cset->subsys)); |
| |
| spin_lock_irq(&css_set_lock); |
| /* Add reference counts and links from the new css_set. */ |
| list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
| struct cgroup *c = link->cgrp; |
| |
| if (c->root == cgrp->root) |
| c = cgrp; |
| link_css_set(&tmp_links, cset, c); |
| } |
| |
| BUG_ON(!list_empty(&tmp_links)); |
| |
| css_set_count++; |
| |
| /* Add @cset to the hash table */ |
| key = css_set_hash(cset->subsys); |
| hash_add(css_set_table, &cset->hlist, key); |
| |
| for_each_subsys(ss, ssid) { |
| struct cgroup_subsys_state *css = cset->subsys[ssid]; |
| |
| list_add_tail(&cset->e_cset_node[ssid], |
| &css->cgroup->e_csets[ssid]); |
| css_get(css); |
| } |
| |
| spin_unlock_irq(&css_set_lock); |
| |
| /* |
| * If @cset should be threaded, look up the matching dom_cset and |
| * link them up. We first fully initialize @cset then look for the |
| * dom_cset. It's simpler this way and safe as @cset is guaranteed |
| * to stay empty until we return. |
| */ |
| if (cgroup_is_threaded(cset->dfl_cgrp)) { |
| struct css_set *dcset; |
| |
| dcset = find_css_set(cset, cset->dfl_cgrp->dom_cgrp); |
| if (!dcset) { |
| put_css_set(cset); |
| return NULL; |
| } |
| |
| spin_lock_irq(&css_set_lock); |
| cset->dom_cset = dcset; |
| list_add_tail(&cset->threaded_csets_node, |
| &dcset->threaded_csets); |
| spin_unlock_irq(&css_set_lock); |
| } |
| |
| return cset; |
| } |
| |
| struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root) |
| { |
| struct cgroup *root_cgrp = kf_root->kn->priv; |
| |
| return root_cgrp->root; |
| } |
| |
| static int cgroup_init_root_id(struct cgroup_root *root) |
| { |
| int id; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL); |
| if (id < 0) |
| return id; |
| |
| root->hierarchy_id = id; |
| return 0; |
| } |
| |
| static void cgroup_exit_root_id(struct cgroup_root *root) |
| { |
| lockdep_assert_held(&cgroup_mutex); |
| |
| idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); |
| } |
| |
| void cgroup_free_root(struct cgroup_root *root) |
| { |
| if (root) { |
| idr_destroy(&root->cgroup_idr); |
| kfree(root); |
| } |
| } |
| |
| static void cgroup_destroy_root(struct cgroup_root *root) |
| { |
| struct cgroup *cgrp = &root->cgrp; |
| struct cgrp_cset_link *link, *tmp_link; |
| |
| trace_cgroup_destroy_root(root); |
| |
| cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp); |
| |
| BUG_ON(atomic_read(&root->nr_cgrps)); |
| BUG_ON(!list_empty(&cgrp->self.children)); |
| |
| /* Rebind all subsystems back to the default hierarchy */ |
| WARN_ON(rebind_subsystems(&cgrp_dfl_root, root->subsys_mask)); |
| |
| /* |
| * Release all the links from cset_links to this hierarchy's |
| * root cgroup |
| */ |
| spin_lock_irq(&css_set_lock); |
| |
| list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { |
| list_del(&link->cset_link); |
| list_del(&link->cgrp_link); |
| kfree(link); |
| } |
| |
| spin_unlock_irq(&css_set_lock); |
| |
| if (!list_empty(&root->root_list)) { |
| list_del(&root->root_list); |
| cgroup_root_count--; |
| } |
| |
| cgroup_exit_root_id(root); |
| |
| mutex_unlock(&cgroup_mutex); |
| |
| kernfs_destroy_root(root->kf_root); |
| cgroup_free_root(root); |
| } |
| |
| /* |
| * look up cgroup associated with current task's cgroup namespace on the |
| * specified hierarchy |
| */ |
| static struct cgroup * |
| current_cgns_cgroup_from_root(struct cgroup_root *root) |
| { |
| struct cgroup *res = NULL; |
| struct css_set *cset; |
| |
| lockdep_assert_held(&css_set_lock); |
| |
| rcu_read_lock(); |
| |
| cset = current->nsproxy->cgroup_ns->root_cset; |
| if (cset == &init_css_set) { |
| res = &root->cgrp; |
| } else { |
| struct cgrp_cset_link *link; |
| |
| list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
| struct cgroup *c = link->cgrp; |
| |
| if (c->root == root) { |
| res = c; |
| break; |
| } |
| } |
| } |
| rcu_read_unlock(); |
| |
| BUG_ON(!res); |
| return res; |
| } |
| |
| /* look up cgroup associated with given css_set on the specified hierarchy */ |
| static struct cgroup *cset_cgroup_from_root(struct css_set *cset, |
| struct cgroup_root *root) |
| { |
| struct cgroup *res = NULL; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| lockdep_assert_held(&css_set_lock); |
| |
| if (cset == &init_css_set) { |
| res = &root->cgrp; |
| } else if (root == &cgrp_dfl_root) { |
| res = cset->dfl_cgrp; |
| } else { |
| struct cgrp_cset_link *link; |
| |
| list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
| struct cgroup *c = link->cgrp; |
| |
| if (c->root == root) { |
| res = c; |
| break; |
| } |
| } |
| } |
| |
| BUG_ON(!res); |
| return res; |
| } |
| |
| /* |
| * Return the cgroup for "task" from the given hierarchy. Must be |
| * called with cgroup_mutex and css_set_lock held. |
| */ |
| struct cgroup *task_cgroup_from_root(struct task_struct *task, |
| struct cgroup_root *root) |
| { |
| /* |
| * No need to lock the task - since we hold cgroup_mutex the |
| * task can't change groups, so the only thing that can happen |
| * is that it exits and its css is set back to init_css_set. |
| */ |
| return cset_cgroup_from_root(task_css_set(task), root); |
| } |
| |
| /* |
| * A task must hold cgroup_mutex to modify cgroups. |
| * |
| * Any task can increment and decrement the count field without lock. |
| * So in general, code holding cgroup_mutex can't rely on the count |
| * field not changing. However, if the count goes to zero, then only |
| * cgroup_attach_task() can increment it again. Because a count of zero |
| * means that no tasks are currently attached, therefore there is no |
| * way a task attached to that cgroup can fork (the other way to |
| * increment the count). So code holding cgroup_mutex can safely |
| * assume that if the count is zero, it will stay zero. Similarly, if |
| * a task holds cgroup_mutex on a cgroup with zero count, it |
| * knows that the cgroup won't be removed, as cgroup_rmdir() |
| * needs that mutex. |
| * |
| * A cgroup can only be deleted if both its 'count' of using tasks |
| * is zero, and its list of 'children' cgroups is empty. Since all |
| * tasks in the system use _some_ cgroup, and since there is always at |
| * least one task in the system (init, pid == 1), therefore, root cgroup |
| * always has either children cgroups and/or using tasks. So we don't |
| * need a special hack to ensure that root cgroup cannot be deleted. |
| * |
| * P.S. One more locking exception. RCU is used to guard the |
| * update of a tasks cgroup pointer by cgroup_attach_task() |
| */ |
| |
| static struct kernfs_syscall_ops cgroup_kf_syscall_ops; |
| |
| static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, |
| char *buf) |
| { |
| struct cgroup_subsys *ss = cft->ss; |
| |
| if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) && |
| !(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) { |
| const char *dbg = (cft->flags & CFTYPE_DEBUG) ? ".__DEBUG__." : ""; |
| |
| snprintf(buf, CGROUP_FILE_NAME_MAX, "%s%s.%s", |
| dbg, cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name, |
| cft->name); |
| } else { |
| strscpy(buf, cft->name, CGROUP_FILE_NAME_MAX); |
| } |
| return buf; |
| } |
| |
| /** |
| * cgroup_file_mode - deduce file mode of a control file |
| * @cft: the control file in question |
| * |
| * S_IRUGO for read, S_IWUSR for write. |
| */ |
| static umode_t cgroup_file_mode(const struct cftype *cft) |
| { |
| umode_t mode = 0; |
| |
| if (cft->read_u64 || cft->read_s64 || cft->seq_show) |
| mode |= S_IRUGO; |
| |
| if (cft->write_u64 || cft->write_s64 || cft->write) { |
| if (cft->flags & CFTYPE_WORLD_WRITABLE) |
| mode |= S_IWUGO; |
| else |
| mode |= S_IWUSR; |
| } |
| |
| return mode; |
| } |
| |
| /** |
| * cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask |
| * @subtree_control: the new subtree_control mask to consider |
| * @this_ss_mask: available subsystems |
| * |
| * On the default hierarchy, a subsystem may request other subsystems to be |
| * enabled together through its ->depends_on mask. In such cases, more |
| * subsystems than specified in "cgroup.subtree_control" may be enabled. |
| * |
| * This function calculates which subsystems need to be enabled if |
| * @subtree_control is to be applied while restricted to @this_ss_mask. |
| */ |
| static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask) |
| { |
| u16 cur_ss_mask = subtree_control; |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| cur_ss_mask |= cgrp_dfl_implicit_ss_mask; |
| |
| while (true) { |
| u16 new_ss_mask = cur_ss_mask; |
| |
| do_each_subsys_mask(ss, ssid, cur_ss_mask) { |
| new_ss_mask |= ss->depends_on; |
| } while_each_subsys_mask(); |
| |
| /* |
| * Mask out subsystems which aren't available. This can |
| * happen only if some depended-upon subsystems were bound |
| * to non-default hierarchies. |
| */ |
| new_ss_mask &= this_ss_mask; |
| |
| if (new_ss_mask == cur_ss_mask) |
| break; |
| cur_ss_mask = new_ss_mask; |
| } |
| |
| return cur_ss_mask; |
| } |
| |
| /** |
| * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods |
| * @kn: the kernfs_node being serviced |
| * |
| * This helper undoes cgroup_kn_lock_live() and should be invoked before |
| * the method finishes if locking succeeded. Note that once this function |
| * returns the cgroup returned by cgroup_kn_lock_live() may become |
| * inaccessible any time. If the caller intends to continue to access the |
| * cgroup, it should pin it before invoking this function. |
| */ |
| void cgroup_kn_unlock(struct kernfs_node *kn) |
| { |
| struct cgroup *cgrp; |
| |
| if (kernfs_type(kn) == KERNFS_DIR) |
| cgrp = kn->priv; |
| else |
| cgrp = kn->parent->priv; |
| |
| mutex_unlock(&cgroup_mutex); |
| |
| kernfs_unbreak_active_protection(kn); |
| cgroup_put(cgrp); |
| } |
| |
| /** |
| * cgroup_kn_lock_live - locking helper for cgroup kernfs methods |
| * @kn: the kernfs_node being serviced |
| * @drain_offline: perform offline draining on the cgroup |
| * |
| * This helper is to be used by a cgroup kernfs method currently servicing |
| * @kn. It breaks the active protection, performs cgroup locking and |
| * verifies that the associated cgroup is alive. Returns the cgroup if |
| * alive; otherwise, %NULL. A successful return should be undone by a |
| * matching cgroup_kn_unlock() invocation. If @drain_offline is %true, the |
| * cgroup is drained of offlining csses before return. |
| * |
| * Any cgroup kernfs method implementation which requires locking the |
| * associated cgroup should use this helper. It avoids nesting cgroup |
| * locking under kernfs active protection and allows all kernfs operations |
| * including self-removal. |
| */ |
| struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline) |
| { |
| struct cgroup *cgrp; |
| |
| if (kernfs_type(kn) == KERNFS_DIR) |
| cgrp = kn->priv; |
| else |
| cgrp = kn->parent->priv; |
| |
| /* |
| * We're gonna grab cgroup_mutex which nests outside kernfs |
| * active_ref. cgroup liveliness check alone provides enough |
| * protection against removal. Ensure @cgrp stays accessible and |
| * break the active_ref protection. |
| */ |
| if (!cgroup_tryget(cgrp)) |
| return NULL; |
| kernfs_break_active_protection(kn); |
| |
| if (drain_offline) |
| cgroup_lock_and_drain_offline(cgrp); |
| else |
| mutex_lock(&cgroup_mutex); |
| |
| if (!cgroup_is_dead(cgrp)) |
| return cgrp; |
| |
| cgroup_kn_unlock(kn); |
| return NULL; |
| } |
| |
| static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
| { |
| char name[CGROUP_FILE_NAME_MAX]; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| if (cft->file_offset) { |
| struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss); |
| struct cgroup_file *cfile = (void *)css + cft->file_offset; |
| |
| spin_lock_irq(&cgroup_file_kn_lock); |
| cfile->kn = NULL; |
| spin_unlock_irq(&cgroup_file_kn_lock); |
| |
| del_timer_sync(&cfile->notify_timer); |
| } |
| |
| kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); |
| } |
| |
| /** |
| * css_clear_dir - remove subsys files in a cgroup directory |
| * @css: taget css |
| */ |
| static void css_clear_dir(struct cgroup_subsys_state *css) |
| { |
| struct cgroup *cgrp = css->cgroup; |
| struct cftype *cfts; |
| |
| if (!(css->flags & CSS_VISIBLE)) |
| return; |
| |
| css->flags &= ~CSS_VISIBLE; |
| |
| if (!css->ss) { |
| if (cgroup_on_dfl(cgrp)) |
| cfts = cgroup_base_files; |
| else |
| cfts = cgroup1_base_files; |
| |
| cgroup_addrm_files(css, cgrp, cfts, false); |
| } else { |
| list_for_each_entry(cfts, &css->ss->cfts, node) |
| cgroup_addrm_files(css, cgrp, cfts, false); |
| } |
| } |
| |
| /** |
| * css_populate_dir - create subsys files in a cgroup directory |
| * @css: target css |
| * |
| * On failure, no file is added. |
| */ |
| static int css_populate_dir(struct cgroup_subsys_state *css) |
| { |
| struct cgroup *cgrp = css->cgroup; |
| struct cftype *cfts, *failed_cfts; |
| int ret; |
| |
| if ((css->flags & CSS_VISIBLE) || !cgrp->kn) |
| return 0; |
| |
| if (!css->ss) { |
| if (cgroup_on_dfl(cgrp)) |
| cfts = cgroup_base_files; |
| else |
| cfts = cgroup1_base_files; |
| |
| ret = cgroup_addrm_files(&cgrp->self, cgrp, cfts, true); |
| if (ret < 0) |
| return ret; |
| } else { |
| list_for_each_entry(cfts, &css->ss->cfts, node) { |
| ret = cgroup_addrm_files(css, cgrp, cfts, true); |
| if (ret < 0) { |
| failed_cfts = cfts; |
| goto err; |
| } |
| } |
| } |
| |
| css->flags |= CSS_VISIBLE; |
| |
| return 0; |
| err: |
| list_for_each_entry(cfts, &css->ss->cfts, node) { |
| if (cfts == failed_cfts) |
| break; |
| cgroup_addrm_files(css, cgrp, cfts, false); |
| } |
| return ret; |
| } |
| |
| int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask) |
| { |
| struct cgroup *dcgrp = &dst_root->cgrp; |
| struct cgroup_subsys *ss; |
| int ssid, i, ret; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| do_each_subsys_mask(ss, ssid, ss_mask) { |
| /* |
| * If @ss has non-root csses attached to it, can't move. |
| * If @ss is an implicit controller, it is exempt from this |
| * rule and can be stolen. |
| */ |
| if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss)) && |
| !ss->implicit_on_dfl) |
| return -EBUSY; |
| |
| /* can't move between two non-dummy roots either */ |
| if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root) |
| return -EBUSY; |
| } while_each_subsys_mask(); |
| |
| do_each_subsys_mask(ss, ssid, ss_mask) { |
| struct cgroup_root *src_root = ss->root; |
| struct cgroup *scgrp = &src_root->cgrp; |
| struct cgroup_subsys_state *css = cgroup_css(scgrp, ss); |
| struct css_set *cset; |
| |
| WARN_ON(!css || cgroup_css(dcgrp, ss)); |
| |
| /* disable from the source */ |
| src_root->subsys_mask &= ~(1 << ssid); |
| WARN_ON(cgroup_apply_control(scgrp)); |
| cgroup_finalize_control(scgrp, 0); |
| |
| /* rebind */ |
| RCU_INIT_POINTER(scgrp->subsys[ssid], NULL); |
| rcu_assign_pointer(dcgrp->subsys[ssid], css); |
| ss->root = dst_root; |
| css->cgroup = dcgrp; |
| |
| spin_lock_irq(&css_set_lock); |
| hash_for_each(css_set_table, i, cset, hlist) |
| list_move_tail(&cset->e_cset_node[ss->id], |
| &dcgrp->e_csets[ss->id]); |
| spin_unlock_irq(&css_set_lock); |
| |
| /* default hierarchy doesn't enable controllers by default */ |
| dst_root->subsys_mask |= 1 << ssid; |
| if (dst_root == &cgrp_dfl_root) { |
| static_branch_enable(cgroup_subsys_on_dfl_key[ssid]); |
| } else { |
| dcgrp->subtree_control |= 1 << ssid; |
| static_branch_disable(cgroup_subsys_on_dfl_key[ssid]); |
| } |
| |
| ret = cgroup_apply_control(dcgrp); |
| if (ret) |
| pr_warn("partial failure to rebind %s controller (err=%d)\n", |
| ss->name, ret); |
| |
| if (ss->bind) |
| ss->bind(css); |
| } while_each_subsys_mask(); |
| |
| kernfs_activate(dcgrp->kn); |
| return 0; |
| } |
| |
| int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node, |
| struct kernfs_root *kf_root) |
| { |
| int len = 0; |
| char *buf = NULL; |
| struct cgroup_root *kf_cgroot = cgroup_root_from_kf(kf_root); |
| struct cgroup *ns_cgroup; |
| |
| buf = kmalloc(PATH_MAX, GFP_KERNEL); |
| if (!buf) |
| return -ENOMEM; |
| |
| spin_lock_irq(&css_set_lock); |
| ns_cgroup = current_cgns_cgroup_from_root(kf_cgroot); |
| len = kernfs_path_from_node(kf_node, ns_cgroup->kn, buf, PATH_MAX); |
| spin_unlock_irq(&css_set_lock); |
| |
| if (len >= PATH_MAX) |
| len = -ERANGE; |
| else if (len > 0) { |
| seq_escape(sf, buf, " \t\n\\"); |
| len = 0; |
| } |
| kfree(buf); |
| return len; |
| } |
| |
| enum cgroup2_param { |
| Opt_nsdelegate, |
| Opt_memory_localevents, |
| nr__cgroup2_params |
| }; |
| |
| static const struct fs_parameter_spec cgroup2_param_specs[] = { |
| fsparam_flag("nsdelegate", Opt_nsdelegate), |
| fsparam_flag("memory_localevents", Opt_memory_localevents), |
| {} |
| }; |
| |
| static const struct fs_parameter_description cgroup2_fs_parameters = { |
| .name = "cgroup2", |
| .specs = cgroup2_param_specs, |
| }; |
| |
| static int cgroup2_parse_param(struct fs_context *fc, struct fs_parameter *param) |
| { |
| struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
| struct fs_parse_result result; |
| int opt; |
| |
| opt = fs_parse(fc, &cgroup2_fs_parameters, param, &result); |
| if (opt < 0) |
| return opt; |
| |
| switch (opt) { |
| case Opt_nsdelegate: |
| ctx->flags |= CGRP_ROOT_NS_DELEGATE; |
| return 0; |
| case Opt_memory_localevents: |
| ctx->flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS; |
| return 0; |
| } |
| return -EINVAL; |
| } |
| |
| static void apply_cgroup_root_flags(unsigned int root_flags) |
| { |
| if (current->nsproxy->cgroup_ns == &init_cgroup_ns) { |
| if (root_flags & CGRP_ROOT_NS_DELEGATE) |
| cgrp_dfl_root.flags |= CGRP_ROOT_NS_DELEGATE; |
| else |
| cgrp_dfl_root.flags &= ~CGRP_ROOT_NS_DELEGATE; |
| |
| if (root_flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS) |
| cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS; |
| else |
| cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_LOCAL_EVENTS; |
| } |
| } |
| |
| static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root) |
| { |
| if (cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE) |
| seq_puts(seq, ",nsdelegate"); |
| if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS) |
| seq_puts(seq, ",memory_localevents"); |
| return 0; |
| } |
| |
| static int cgroup_reconfigure(struct fs_context *fc) |
| { |
| struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
| |
| apply_cgroup_root_flags(ctx->flags); |
| return 0; |
| } |
| |
| /* |
| * To reduce the fork() overhead for systems that are not actually using |
| * their cgroups capability, we don't maintain the lists running through |
| * each css_set to its tasks until we see the list actually used - in other |
| * words after the first mount. |
| */ |
| static bool use_task_css_set_links __read_mostly; |
| |
| static void cgroup_enable_task_cg_lists(void) |
| { |
| struct task_struct *p, *g; |
| |
| /* |
| * We need tasklist_lock because RCU is not safe against |
| * while_each_thread(). Besides, a forking task that has passed |
| * cgroup_post_fork() without seeing use_task_css_set_links = 1 |
| * is not guaranteed to have its child immediately visible in the |
| * tasklist if we walk through it with RCU. |
| */ |
| read_lock(&tasklist_lock); |
| spin_lock_irq(&css_set_lock); |
| |
| if (use_task_css_set_links) |
| goto out_unlock; |
| |
| use_task_css_set_links = true; |
| |
| do_each_thread(g, p) { |
| WARN_ON_ONCE(!list_empty(&p->cg_list) || |
| task_css_set(p) != &init_css_set); |
| |
| /* |
| * We should check if the process is exiting, otherwise |
| * it will race with cgroup_exit() in that the list |
| * entry won't be deleted though the process has exited. |
| * Do it while holding siglock so that we don't end up |
| * racing against cgroup_exit(). |
| * |
| * Interrupts were already disabled while acquiring |
| * the css_set_lock, so we do not need to disable it |
| * again when acquiring the sighand->siglock here. |
| */ |
| spin_lock(&p->sighand->siglock); |
| if (!(p->flags & PF_EXITING)) { |
| struct css_set *cset = task_css_set(p); |
| |
| if (!css_set_populated(cset)) |
| css_set_update_populated(cset, true); |
| list_add_tail(&p->cg_list, &cset->tasks); |
| get_css_set(cset); |
| cset->nr_tasks++; |
| } |
| spin_unlock(&p->sighand->siglock); |
| } while_each_thread(g, p); |
| out_unlock: |
| spin_unlock_irq(&css_set_lock); |
| read_unlock(&tasklist_lock); |
| } |
| |
| static void init_cgroup_housekeeping(struct cgroup *cgrp) |
| { |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| INIT_LIST_HEAD(&cgrp->self.sibling); |
| INIT_LIST_HEAD(&cgrp->self.children); |
| INIT_LIST_HEAD(&cgrp->cset_links); |
| INIT_LIST_HEAD(&cgrp->pidlists); |
| mutex_init(&cgrp->pidlist_mutex); |
| cgrp->self.cgroup = cgrp; |
| cgrp->self.flags |= CSS_ONLINE; |
| cgrp->dom_cgrp = cgrp; |
| cgrp->max_descendants = INT_MAX; |
| cgrp->max_depth = INT_MAX; |
| INIT_LIST_HEAD(&cgrp->rstat_css_list); |
| prev_cputime_init(&cgrp->prev_cputime); |
| |
| for_each_subsys(ss, ssid) |
| INIT_LIST_HEAD(&cgrp->e_csets[ssid]); |
| |
| init_waitqueue_head(&cgrp->offline_waitq); |
| INIT_WORK(&cgrp->release_agent_work, cgroup1_release_agent); |
| } |
| |
| void init_cgroup_root(struct cgroup_fs_context *ctx) |
| { |
| struct cgroup_root *root = ctx->root; |
| struct cgroup *cgrp = &root->cgrp; |
| |
| INIT_LIST_HEAD(&root->root_list); |
| atomic_set(&root->nr_cgrps, 1); |
| cgrp->root = root; |
| init_cgroup_housekeeping(cgrp); |
| idr_init(&root->cgroup_idr); |
| |
| root->flags = ctx->flags; |
| if (ctx->release_agent) |
| strscpy(root->release_agent_path, ctx->release_agent, PATH_MAX); |
| if (ctx->name) |
| strscpy(root->name, ctx->name, MAX_CGROUP_ROOT_NAMELEN); |
| if (ctx->cpuset_clone_children) |
| set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags); |
| } |
| |
| int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask) |
| { |
| LIST_HEAD(tmp_links); |
| struct cgroup *root_cgrp = &root->cgrp; |
| struct kernfs_syscall_ops *kf_sops; |
| struct css_set *cset; |
| int i, ret; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL); |
| if (ret < 0) |
| goto out; |
| root_cgrp->id = ret; |
| root_cgrp->ancestor_ids[0] = ret; |
| |
| ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, |
| 0, GFP_KERNEL); |
| if (ret) |
| goto out; |
| |
| /* |
| * We're accessing css_set_count without locking css_set_lock here, |
| * but that's OK - it can only be increased by someone holding |
| * cgroup_lock, and that's us. Later rebinding may disable |
| * controllers on the default hierarchy and thus create new csets, |
| * which can't be more than the existing ones. Allocate 2x. |
| */ |
| ret = allocate_cgrp_cset_links(2 * css_set_count, &tmp_links); |
| if (ret) |
| goto cancel_ref; |
| |
| ret = cgroup_init_root_id(root); |
| if (ret) |
| goto cancel_ref; |
| |
| kf_sops = root == &cgrp_dfl_root ? |
| &cgroup_kf_syscall_ops : &cgroup1_kf_syscall_ops; |
| |
| root->kf_root = kernfs_create_root(kf_sops, |
| KERNFS_ROOT_CREATE_DEACTIVATED | |
| KERNFS_ROOT_SUPPORT_EXPORTOP, |
| root_cgrp); |
| if (IS_ERR(root->kf_root)) { |
| ret = PTR_ERR(root->kf_root); |
| goto exit_root_id; |
| } |
| root_cgrp->kn = root->kf_root->kn; |
| |
| ret = css_populate_dir(&root_cgrp->self); |
| if (ret) |
| goto destroy_root; |
| |
| ret = rebind_subsystems(root, ss_mask); |
| if (ret) |
| goto destroy_root; |
| |
| ret = cgroup_bpf_inherit(root_cgrp); |
| WARN_ON_ONCE(ret); |
| |
| trace_cgroup_setup_root(root); |
| |
| /* |
| * There must be no failure case after here, since rebinding takes |
| * care of subsystems' refcounts, which are explicitly dropped in |
| * the failure exit path. |
| */ |
| list_add(&root->root_list, &cgroup_roots); |
| cgroup_root_count++; |
| |
| /* |
| * Link the root cgroup in this hierarchy into all the css_set |
| * objects. |
| */ |
| spin_lock_irq(&css_set_lock); |
| hash_for_each(css_set_table, i, cset, hlist) { |
| link_css_set(&tmp_links, cset, root_cgrp); |
| if (css_set_populated(cset)) |
| cgroup_update_populated(root_cgrp, true); |
| } |
| spin_unlock_irq(&css_set_lock); |
| |
| BUG_ON(!list_empty(&root_cgrp->self.children)); |
| BUG_ON(atomic_read(&root->nr_cgrps) != 1); |
| |
| kernfs_activate(root_cgrp->kn); |
| ret = 0; |
| goto out; |
| |
| destroy_root: |
| kernfs_destroy_root(root->kf_root); |
| root->kf_root = NULL; |
| exit_root_id: |
| cgroup_exit_root_id(root); |
| cancel_ref: |
| percpu_ref_exit(&root_cgrp->self.refcnt); |
| out: |
| free_cgrp_cset_links(&tmp_links); |
| return ret; |
| } |
| |
| int cgroup_do_get_tree(struct fs_context *fc) |
| { |
| struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
| int ret; |
| |
| ctx->kfc.root = ctx->root->kf_root; |
| if (fc->fs_type == &cgroup2_fs_type) |
| ctx->kfc.magic = CGROUP2_SUPER_MAGIC; |
| else |
| ctx->kfc.magic = CGROUP_SUPER_MAGIC; |
| ret = kernfs_get_tree(fc); |
| |
| /* |
| * In non-init cgroup namespace, instead of root cgroup's dentry, |
| * we return the dentry corresponding to the cgroupns->root_cgrp. |
| */ |
| if (!ret && ctx->ns != &init_cgroup_ns) { |
| struct dentry *nsdentry; |
| struct super_block *sb = fc->root->d_sb; |
| struct cgroup *cgrp; |
| |
| mutex_lock(&cgroup_mutex); |
| spin_lock_irq(&css_set_lock); |
| |
| cgrp = cset_cgroup_from_root(ctx->ns->root_cset, ctx->root); |
| |
| spin_unlock_irq(&css_set_lock); |
| mutex_unlock(&cgroup_mutex); |
| |
| nsdentry = kernfs_node_dentry(cgrp->kn, sb); |
| dput(fc->root); |
| fc->root = nsdentry; |
| if (IS_ERR(nsdentry)) { |
| ret = PTR_ERR(nsdentry); |
| deactivate_locked_super(sb); |
| } |
| } |
| |
| if (!ctx->kfc.new_sb_created) |
| cgroup_put(&ctx->root->cgrp); |
| |
| return ret; |
| } |
| |
| /* |
| * Destroy a cgroup filesystem context. |
| */ |
| static void cgroup_fs_context_free(struct fs_context *fc) |
| { |
| struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
| |
| kfree(ctx->name); |
| kfree(ctx->release_agent); |
| put_cgroup_ns(ctx->ns); |
| kernfs_free_fs_context(fc); |
| kfree(ctx); |
| } |
| |
| static int cgroup_get_tree(struct fs_context *fc) |
| { |
| struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
| int ret; |
| |
| cgrp_dfl_visible = true; |
| cgroup_get_live(&cgrp_dfl_root.cgrp); |
| ctx->root = &cgrp_dfl_root; |
| |
| ret = cgroup_do_get_tree(fc); |
| if (!ret) |
| apply_cgroup_root_flags(ctx->flags); |
| return ret; |
| } |
| |
| static const struct fs_context_operations cgroup_fs_context_ops = { |
| .free = cgroup_fs_context_free, |
| .parse_param = cgroup2_parse_param, |
| .get_tree = cgroup_get_tree, |
| .reconfigure = cgroup_reconfigure, |
| }; |
| |
| static const struct fs_context_operations cgroup1_fs_context_ops = { |
| .free = cgroup_fs_context_free, |
| .parse_param = cgroup1_parse_param, |
| .get_tree = cgroup1_get_tree, |
| .reconfigure = cgroup1_reconfigure, |
| }; |
| |
| /* |
| * Initialise the cgroup filesystem creation/reconfiguration context. Notably, |
| * we select the namespace we're going to use. |
| */ |
| static int cgroup_init_fs_context(struct fs_context *fc) |
| { |
| struct cgroup_fs_context *ctx; |
| |
| ctx = kzalloc(sizeof(struct cgroup_fs_context), GFP_KERNEL); |
| if (!ctx) |
| return -ENOMEM; |
| |
| /* |
| * The first time anyone tries to mount a cgroup, enable the list |
| * linking each css_set to its tasks and fix up all existing tasks. |
| */ |
| if (!use_task_css_set_links) |
| cgroup_enable_task_cg_lists(); |
| |
| ctx->ns = current->nsproxy->cgroup_ns; |
| get_cgroup_ns(ctx->ns); |
| fc->fs_private = &ctx->kfc; |
| if (fc->fs_type == &cgroup2_fs_type) |
| fc->ops = &cgroup_fs_context_ops; |
| else |
| fc->ops = &cgroup1_fs_context_ops; |
| put_user_ns(fc->user_ns); |
| fc->user_ns = get_user_ns(ctx->ns->user_ns); |
| fc->global = true; |
| return 0; |
| } |
| |
| static void cgroup_kill_sb(struct super_block *sb) |
| { |
| struct kernfs_root *kf_root = kernfs_root_from_sb(sb); |
| struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
| |
| /* |
| * If @root doesn't have any children, start killing it. |
| * This prevents new mounts by disabling percpu_ref_tryget_live(). |
| * cgroup_mount() may wait for @root's release. |
| * |
| * And don't kill the default root. |
| */ |
| if (list_empty(&root->cgrp.self.children) && root != &cgrp_dfl_root && |
| !percpu_ref_is_dying(&root->cgrp.self.refcnt)) |
| percpu_ref_kill(&root->cgrp.self.refcnt); |
| cgroup_put(&root->cgrp); |
| kernfs_kill_sb(sb); |
| } |
| |
| struct file_system_type cgroup_fs_type = { |
| .name = "cgroup", |
| .init_fs_context = cgroup_init_fs_context, |
| .parameters = &cgroup1_fs_parameters, |
| .kill_sb = cgroup_kill_sb, |
| .fs_flags = FS_USERNS_MOUNT, |
| }; |
| |
| static struct file_system_type cgroup2_fs_type = { |
| .name = "cgroup2", |
| .init_fs_context = cgroup_init_fs_context, |
| .parameters = &cgroup2_fs_parameters, |
| .kill_sb = cgroup_kill_sb, |
| .fs_flags = FS_USERNS_MOUNT, |
| }; |
| |
| #ifdef CONFIG_CPUSETS |
| static const struct fs_context_operations cpuset_fs_context_ops = { |
| .get_tree = cgroup1_get_tree, |
| .free = cgroup_fs_context_free, |
| }; |
| |
| /* |
| * This is ugly, but preserves the userspace API for existing cpuset |
| * users. If someone tries to mount the "cpuset" filesystem, we |
| * silently switch it to mount "cgroup" instead |
| */ |
| static int cpuset_init_fs_context(struct fs_context *fc) |
| { |
| char *agent = kstrdup("/sbin/cpuset_release_agent", GFP_USER); |
| struct cgroup_fs_context *ctx; |
| int err; |
| |
| err = cgroup_init_fs_context(fc); |
| if (err) { |
| kfree(agent); |
| return err; |
| } |
| |
| fc->ops = &cpuset_fs_context_ops; |
| |
| ctx = cgroup_fc2context(fc); |
| ctx->subsys_mask = 1 << cpuset_cgrp_id; |
| ctx->flags |= CGRP_ROOT_NOPREFIX; |
| ctx->release_agent = agent; |
| |
| get_filesystem(&cgroup_fs_type); |
| put_filesystem(fc->fs_type); |
| fc->fs_type = &cgroup_fs_type; |
| |
| return 0; |
| } |
| |
| static struct file_system_type cpuset_fs_type = { |
| .name = "cpuset", |
| .init_fs_context = cpuset_init_fs_context, |
| .fs_flags = FS_USERNS_MOUNT, |
| }; |
| #endif |
| |
| int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen, |
| struct cgroup_namespace *ns) |
| { |
| struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root); |
| |
| return kernfs_path_from_node(cgrp->kn, root->kn, buf, buflen); |
| } |
| |
| int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen, |
| struct cgroup_namespace *ns) |
| { |
| int ret; |
| |
| mutex_lock(&cgroup_mutex); |
| spin_lock_irq(&css_set_lock); |
| |
| ret = cgroup_path_ns_locked(cgrp, buf, buflen, ns); |
| |
| spin_unlock_irq(&css_set_lock); |
| mutex_unlock(&cgroup_mutex); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(cgroup_path_ns); |
| |
| /** |
| * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy |
| * @task: target task |
| * @buf: the buffer to write the path into |
| * @buflen: the length of the buffer |
| * |
| * Determine @task's cgroup on the first (the one with the lowest non-zero |
| * hierarchy_id) cgroup hierarchy and copy its path into @buf. This |
| * function grabs cgroup_mutex and shouldn't be used inside locks used by |
| * cgroup controller callbacks. |
| * |
| * Return value is the same as kernfs_path(). |
| */ |
| int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) |
| { |
| struct cgroup_root *root; |
| struct cgroup *cgrp; |
| int hierarchy_id = 1; |
| int ret; |
| |
| mutex_lock(&cgroup_mutex); |
| spin_lock_irq(&css_set_lock); |
| |
| root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); |
| |
| if (root) { |
| cgrp = task_cgroup_from_root(task, root); |
| ret = cgroup_path_ns_locked(cgrp, buf, buflen, &init_cgroup_ns); |
| } else { |
| /* if no hierarchy exists, everyone is in "/" */ |
| ret = strlcpy(buf, "/", buflen); |
| } |
| |
| spin_unlock_irq(&css_set_lock); |
| mutex_unlock(&cgroup_mutex); |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(task_cgroup_path); |
| |
| /** |
| * cgroup_migrate_add_task - add a migration target task to a migration context |
| * @task: target task |
| * @mgctx: target migration context |
| * |
| * Add @task, which is a migration target, to @mgctx->tset. This function |
| * becomes noop if @task doesn't need to be migrated. @task's css_set |
| * should have been added as a migration source and @task->cg_list will be |
| * moved from the css_set's tasks list to mg_tasks one. |
| */ |
| static void cgroup_migrate_add_task(struct task_struct *task, |
| struct cgroup_mgctx *mgctx) |
| { |
| struct css_set *cset; |
| |
| lockdep_assert_held(&css_set_lock); |
| |
| /* @task either already exited or can't exit until the end */ |
| if (task->flags & PF_EXITING) |
| return; |
| |
| /* leave @task alone if post_fork() hasn't linked it yet */ |
| if (list_empty(&task->cg_list)) |
| return; |
| |
| cset = task_css_set(task); |
| if (!cset->mg_src_cgrp) |
| return; |
| |
| mgctx->tset.nr_tasks++; |
| |
| list_move_tail(&task->cg_list, &cset->mg_tasks); |
| if (list_empty(&cset->mg_node)) |
| list_add_tail(&cset->mg_node, |
| &mgctx->tset.src_csets); |
| if (list_empty(&cset->mg_dst_cset->mg_node)) |
| list_add_tail(&cset->mg_dst_cset->mg_node, |
| &mgctx->tset.dst_csets); |
| } |
| |
| /** |
| * cgroup_taskset_first - reset taskset and return the first task |
| * @tset: taskset of interest |
| * @dst_cssp: output variable for the destination css |
| * |
| * @tset iteration is initialized and the first task is returned. |
| */ |
| struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset, |
| struct cgroup_subsys_state **dst_cssp) |
| { |
| tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node); |
| tset->cur_task = NULL; |
| |
| return cgroup_taskset_next(tset, dst_cssp); |
| } |
| |
| /** |
| * cgroup_taskset_next - iterate to the next task in taskset |
| * @tset: taskset of interest |
| * @dst_cssp: output variable for the destination css |
| * |
| * Return the next task in @tset. Iteration must have been initialized |
| * with cgroup_taskset_first(). |
| */ |
| struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset, |
| struct cgroup_subsys_state **dst_cssp) |
| { |
| struct css_set *cset = tset->cur_cset; |
| struct task_struct *task = tset->cur_task; |
| |
| while (&cset->mg_node != tset->csets) { |
| if (!task) |
| task = list_first_entry(&cset->mg_tasks, |
| struct task_struct, cg_list); |
| else |
| task = list_next_entry(task, cg_list); |
| |
| if (&task->cg_list != &cset->mg_tasks) { |
| tset->cur_cset = cset; |
| tset->cur_task = task; |
| |
| /* |
| * This function may be called both before and |
| * after cgroup_taskset_migrate(). The two cases |
| * can be distinguished by looking at whether @cset |
| * has its ->mg_dst_cset set. |
| */ |
| if (cset->mg_dst_cset) |
| *dst_cssp = cset->mg_dst_cset->subsys[tset->ssid]; |
| else |
| *dst_cssp = cset->subsys[tset->ssid]; |
| |
| return task; |
| } |
| |
| cset = list_next_entry(cset, mg_node); |
| task = NULL; |
| } |
| |
| return NULL; |
| } |
| |
| /** |
| * cgroup_taskset_migrate - migrate a taskset |
| * @mgctx: migration context |
| * |
| * Migrate tasks in @mgctx as setup by migration preparation functions. |
| * This function fails iff one of the ->can_attach callbacks fails and |
| * guarantees that either all or none of the tasks in @mgctx are migrated. |
| * @mgctx is consumed regardless of success. |
| */ |
| static int cgroup_migrate_execute(struct cgroup_mgctx *mgctx) |
| { |
| struct cgroup_taskset *tset = &mgctx->tset; |
| struct cgroup_subsys *ss; |
| struct task_struct *task, *tmp_task; |
| struct css_set *cset, *tmp_cset; |
| int ssid, failed_ssid, ret; |
| |
| /* check that we can legitimately attach to the cgroup */ |
| if (tset->nr_tasks) { |
| do_each_subsys_mask(ss, ssid, mgctx->ss_mask) { |
| if (ss->can_attach) { |
| tset->ssid = ssid; |
| ret = ss->can_attach(tset); |
| if (ret) { |
| failed_ssid = ssid; |
| goto out_cancel_attach; |
| } |
| } |
| } while_each_subsys_mask(); |
| } |
| |
| /* |
| * Now that we're guaranteed success, proceed to move all tasks to |
| * the new cgroup. There are no failure cases after here, so this |
| * is the commit point. |
| */ |
| spin_lock_irq(&css_set_lock); |
| list_for_each_entry(cset, &tset->src_csets, mg_node) { |
| list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) { |
| struct css_set *from_cset = task_css_set(task); |
| struct css_set *to_cset = cset->mg_dst_cset; |
| |
| get_css_set(to_cset); |
| to_cset->nr_tasks++; |
| css_set_move_task(task, from_cset, to_cset, true); |
| from_cset->nr_tasks--; |
| /* |
| * If the source or destination cgroup is frozen, |
| * the task might require to change its state. |
| */ |
| cgroup_freezer_migrate_task(task, from_cset->dfl_cgrp, |
| to_cset->dfl_cgrp); |
| put_css_set_locked(from_cset); |
| |
| } |
| } |
| spin_unlock_irq(&css_set_lock); |
| |
| /* |
| * Migration is committed, all target tasks are now on dst_csets. |
| * Nothing is sensitive to fork() after this point. Notify |
| * controllers that migration is complete. |
| */ |
| tset->csets = &tset->dst_csets; |
| |
| if (tset->nr_tasks) { |
| do_each_subsys_mask(ss, ssid, mgctx->ss_mask) { |
| if (ss->attach) { |
| tset->ssid = ssid; |
| ss->attach(tset); |
| } |
| } while_each_subsys_mask(); |
| } |
| |
| ret = 0; |
| goto out_release_tset; |
| |
| out_cancel_attach: |
| if (tset->nr_tasks) { |
| do_each_subsys_mask(ss, ssid, mgctx->ss_mask) { |
| if (ssid == failed_ssid) |
| break; |
| if (ss->cancel_attach) { |
| tset->ssid = ssid; |
| ss->cancel_attach(tset); |
| } |
| } while_each_subsys_mask(); |
| } |
| out_release_tset: |
| spin_lock_irq(&css_set_lock); |
| list_splice_init(&tset->dst_csets, &tset->src_csets); |
| list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) { |
| list_splice_tail_init(&cset->mg_tasks, &cset->tasks); |
| list_del_init(&cset->mg_node); |
| } |
| spin_unlock_irq(&css_set_lock); |
| |
| /* |
| * Re-initialize the cgroup_taskset structure in case it is reused |
| * again in another cgroup_migrate_add_task()/cgroup_migrate_execute() |
| * iteration. |
| */ |
| tset->nr_tasks = 0; |
| tset->csets = &tset->src_csets; |
| return ret; |
| } |
| |
| /** |
| * cgroup_migrate_vet_dst - verify whether a cgroup can be migration destination |
| * @dst_cgrp: destination cgroup to test |
| * |
| * On the default hierarchy, except for the mixable, (possible) thread root |
| * and threaded cgroups, subtree_control must be zero for migration |
| * destination cgroups with tasks so that child cgroups don't compete |
| * against tasks. |
| */ |
| int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp) |
| { |
| /* v1 doesn't have any restriction */ |
| if (!cgroup_on_dfl(dst_cgrp)) |
| return 0; |
| |
| /* verify @dst_cgrp can host resources */ |
| if (!cgroup_is_valid_domain(dst_cgrp->dom_cgrp)) |
| return -EOPNOTSUPP; |
| |
| /* mixables don't care */ |
| if (cgroup_is_mixable(dst_cgrp)) |
| return 0; |
| |
| /* |
| * If @dst_cgrp is already or can become a thread root or is |
| * threaded, it doesn't matter. |
| */ |
| if (cgroup_can_be_thread_root(dst_cgrp) || cgroup_is_threaded(dst_cgrp)) |
| return 0; |
| |
| /* apply no-internal-process constraint */ |
| if (dst_cgrp->subtree_control) |
| return -EBUSY; |
| |
| return 0; |
| } |
| |
| /** |
| * cgroup_migrate_finish - cleanup after attach |
| * @mgctx: migration context |
| * |
| * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See |
| * those functions for details. |
| */ |
| void cgroup_migrate_finish(struct cgroup_mgctx *mgctx) |
| { |
| LIST_HEAD(preloaded); |
| struct css_set *cset, *tmp_cset; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| spin_lock_irq(&css_set_lock); |
| |
| list_splice_tail_init(&mgctx->preloaded_src_csets, &preloaded); |
| list_splice_tail_init(&mgctx->preloaded_dst_csets, &preloaded); |
| |
| list_for_each_entry_safe(cset, tmp_cset, &preloaded, mg_preload_node) { |
| cset->mg_src_cgrp = NULL; |
| cset->mg_dst_cgrp = NULL; |
| cset->mg_dst_cset = NULL; |
| list_del_init(&cset->mg_preload_node); |
| put_css_set_locked(cset); |
| } |
| |
| spin_unlock_irq(&css_set_lock); |
| } |
| |
| /** |
| * cgroup_migrate_add_src - add a migration source css_set |
| * @src_cset: the source css_set to add |
| * @dst_cgrp: the destination cgroup |
| * @mgctx: migration context |
| * |
| * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin |
| * @src_cset and add it to @mgctx->src_csets, which should later be cleaned |
| * up by cgroup_migrate_finish(). |
| * |
| * This function may be called without holding cgroup_threadgroup_rwsem |
| * even if the target is a process. Threads may be created and destroyed |
| * but as long as cgroup_mutex is not dropped, no new css_set can be put |
| * into play and the preloaded css_sets are guaranteed to cover all |
| * migrations. |
| */ |
| void cgroup_migrate_add_src(struct css_set *src_cset, |
| struct cgroup *dst_cgrp, |
| struct cgroup_mgctx *mgctx) |
| { |
| struct cgroup *src_cgrp; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| lockdep_assert_held(&css_set_lock); |
| |
| /* |
| * If ->dead, @src_set is associated with one or more dead cgroups |
| * and doesn't contain any migratable tasks. Ignore it early so |
| * that the rest of migration path doesn't get confused by it. |
| */ |
| if (src_cset->dead) |
| return; |
| |
| src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); |
| |
| if (!list_empty(&src_cset->mg_preload_node)) |
| return; |
| |
| WARN_ON(src_cset->mg_src_cgrp); |
| WARN_ON(src_cset->mg_dst_cgrp); |
| WARN_ON(!list_empty(&src_cset->mg_tasks)); |
| WARN_ON(!list_empty(&src_cset->mg_node)); |
| |
| src_cset->mg_src_cgrp = src_cgrp; |
| src_cset->mg_dst_cgrp = dst_cgrp; |
| get_css_set(src_cset); |
| list_add_tail(&src_cset->mg_preload_node, &mgctx->preloaded_src_csets); |
| } |
| |
| /** |
| * cgroup_migrate_prepare_dst - prepare destination css_sets for migration |
| * @mgctx: migration context |
| * |
| * Tasks are about to be moved and all the source css_sets have been |
| * preloaded to @mgctx->preloaded_src_csets. This function looks up and |
| * pins all destination css_sets, links each to its source, and append them |
| * to @mgctx->preloaded_dst_csets. |
| * |
| * This function must be called after cgroup_migrate_add_src() has been |
| * called on each migration source css_set. After migration is performed |
| * using cgroup_migrate(), cgroup_migrate_finish() must be called on |
| * @mgctx. |
| */ |
| int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx) |
| { |
| struct css_set *src_cset, *tmp_cset; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| /* look up the dst cset for each src cset and link it to src */ |
| list_for_each_entry_safe(src_cset, tmp_cset, &mgctx->preloaded_src_csets, |
| mg_preload_node) { |
| struct css_set *dst_cset; |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| dst_cset = find_css_set(src_cset, src_cset->mg_dst_cgrp); |
| if (!dst_cset) |
| return -ENOMEM; |
| |
| WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset); |
| |
| /* |
| * If src cset equals dst, it's noop. Drop the src. |
| * cgroup_migrate() will skip the cset too. Note that we |
| * can't handle src == dst as some nodes are used by both. |
| */ |
| if (src_cset == dst_cset) { |
| src_cset->mg_src_cgrp = NULL; |
| src_cset->mg_dst_cgrp = NULL; |
| list_del_init(&src_cset->mg_preload_node); |
| put_css_set(src_cset); |
| put_css_set(dst_cset); |
| continue; |
| } |
| |
| src_cset->mg_dst_cset = dst_cset; |
| |
| if (list_empty(&dst_cset->mg_preload_node)) |
| list_add_tail(&dst_cset->mg_preload_node, |
| &mgctx->preloaded_dst_csets); |
| else |
| put_css_set(dst_cset); |
| |
| for_each_subsys(ss, ssid) |
| if (src_cset->subsys[ssid] != dst_cset->subsys[ssid]) |
| mgctx->ss_mask |= 1 << ssid; |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * cgroup_migrate - migrate a process or task to a cgroup |
| * @leader: the leader of the process or the task to migrate |
| * @threadgroup: whether @leader points to the whole process or a single task |
| * @mgctx: migration context |
| * |
| * Migrate a process or task denoted by @leader. If migrating a process, |
| * the caller must be holding cgroup_threadgroup_rwsem. The caller is also |
| * responsible for invoking cgroup_migrate_add_src() and |
| * cgroup_migrate_prepare_dst() on the targets before invoking this |
| * function and following up with cgroup_migrate_finish(). |
| * |
| * As long as a controller's ->can_attach() doesn't fail, this function is |
| * guaranteed to succeed. This means that, excluding ->can_attach() |
| * failure, when migrating multiple targets, the success or failure can be |
| * decided for all targets by invoking group_migrate_prepare_dst() before |
| * actually starting migrating. |
| */ |
| int cgroup_migrate(struct task_struct *leader, bool threadgroup, |
| struct cgroup_mgctx *mgctx) |
| { |
| struct task_struct *task; |
| |
| /* |
| * Prevent freeing of tasks while we take a snapshot. Tasks that are |
| * already PF_EXITING could be freed from underneath us unless we |
| * take an rcu_read_lock. |
| */ |
| spin_lock_irq(&css_set_lock); |
| rcu_read_lock(); |
| task = leader; |
| do { |
| cgroup_migrate_add_task(task, mgctx); |
| if (!threadgroup) |
| break; |
| } while_each_thread(leader, task); |
| rcu_read_unlock(); |
| spin_unlock_irq(&css_set_lock); |
| |
| return cgroup_migrate_execute(mgctx); |
| } |
| |
| /** |
| * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup |
| * @dst_cgrp: the cgroup to attach to |
| * @leader: the task or the leader of the threadgroup to be attached |
| * @threadgroup: attach the whole threadgroup? |
| * |
| * Call holding cgroup_mutex and cgroup_threadgroup_rwsem. |
| */ |
| int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader, |
| bool threadgroup) |
| { |
| DEFINE_CGROUP_MGCTX(mgctx); |
| struct task_struct *task; |
| int ret; |
| |
| ret = cgroup_migrate_vet_dst(dst_cgrp); |
| if (ret) |
| return ret; |
| |
| /* look up all src csets */ |
| spin_lock_irq(&css_set_lock); |
| rcu_read_lock(); |
| task = leader; |
| do { |
| cgroup_migrate_add_src(task_css_set(task), dst_cgrp, &mgctx); |
| if (!threadgroup) |
| break; |
| } while_each_thread(leader, task); |
| rcu_read_unlock(); |
| spin_unlock_irq(&css_set_lock); |
| |
| /* prepare dst csets and commit */ |
| ret = cgroup_migrate_prepare_dst(&mgctx); |
| if (!ret) |
| ret = cgroup_migrate(leader, threadgroup, &mgctx); |
| |
| cgroup_migrate_finish(&mgctx); |
| |
| if (!ret) |
| TRACE_CGROUP_PATH(attach_task, dst_cgrp, leader, threadgroup); |
| |
| return ret; |
| } |
| |
| struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup) |
| __acquires(&cgroup_threadgroup_rwsem) |
| { |
| struct task_struct *tsk; |
| pid_t pid; |
| |
| if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) |
| return ERR_PTR(-EINVAL); |
| |
| percpu_down_write(&cgroup_threadgroup_rwsem); |
| |
| rcu_read_lock(); |
| if (pid) { |
| tsk = find_task_by_vpid(pid); |
| if (!tsk) { |
| tsk = ERR_PTR(-ESRCH); |
| goto out_unlock_threadgroup; |
| } |
| } else { |
| tsk = current; |
| } |
| |
| if (threadgroup) |
| tsk = tsk->group_leader; |
| |
| /* |
| * kthreads may acquire PF_NO_SETAFFINITY during initialization. |
| * If userland migrates such a kthread to a non-root cgroup, it can |
| * become trapped in a cpuset, or RT kthread may be born in a |
| * cgroup with no rt_runtime allocated. Just say no. |
| */ |
| if (tsk->no_cgroup_migration || (tsk->flags & PF_NO_SETAFFINITY)) { |
| tsk = ERR_PTR(-EINVAL); |
| goto out_unlock_threadgroup; |
| } |
| |
| get_task_struct(tsk); |
| goto out_unlock_rcu; |
| |
| out_unlock_threadgroup: |
| percpu_up_write(&cgroup_threadgroup_rwsem); |
| out_unlock_rcu: |
| rcu_read_unlock(); |
| return tsk; |
| } |
| |
| void cgroup_procs_write_finish(struct task_struct *task) |
| __releases(&cgroup_threadgroup_rwsem) |
| { |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| /* release reference from cgroup_procs_write_start() */ |
| put_task_struct(task); |
| |
| percpu_up_write(&cgroup_threadgroup_rwsem); |
| for_each_subsys(ss, ssid) |
| if (ss->post_attach) |
| ss->post_attach(); |
| } |
| |
| static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask) |
| { |
| struct cgroup_subsys *ss; |
| bool printed = false; |
| int ssid; |
| |
| do_each_subsys_mask(ss, ssid, ss_mask) { |
| if (printed) |
| seq_putc(seq, ' '); |
| seq_printf(seq, "%s", ss->name); |
| printed = true; |
| } while_each_subsys_mask(); |
| if (printed) |
| seq_putc(seq, '\n'); |
| } |
| |
| /* show controllers which are enabled from the parent */ |
| static int cgroup_controllers_show(struct seq_file *seq, void *v) |
| { |
| struct cgroup *cgrp = seq_css(seq)->cgroup; |
| |
| cgroup_print_ss_mask(seq, cgroup_control(cgrp)); |
| return 0; |
| } |
| |
| /* show controllers which are enabled for a given cgroup's children */ |
| static int cgroup_subtree_control_show(struct seq_file *seq, void *v) |
| { |
| struct cgroup *cgrp = seq_css(seq)->cgroup; |
| |
| cgroup_print_ss_mask(seq, cgrp->subtree_control); |
| return 0; |
| } |
| |
| /** |
| * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy |
| * @cgrp: root of the subtree to update csses for |
| * |
| * @cgrp's control masks have changed and its subtree's css associations |
| * need to be updated accordingly. This function looks up all css_sets |
| * which are attached to the subtree, creates the matching updated css_sets |
| * and migrates the tasks to the new ones. |
| */ |
| static int cgroup_update_dfl_csses(struct cgroup *cgrp) |
| { |
| DEFINE_CGROUP_MGCTX(mgctx); |
| struct cgroup_subsys_state *d_css; |
| struct cgroup *dsct; |
| struct css_set *src_cset; |
| int ret; |
| |
| lockdep_assert_held(&cgroup_mutex); |
| |
| percpu_down_write(&cgroup_threadgroup_rwsem); |
| |
| /* look up all csses currently attached to @cgrp's subtree */ |
| spin_lock_irq(&css_set_lock); |
| cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { |
| struct cgrp_cset_link *link; |
| |
| list_for_each_entry(link, &dsct->cset_links, cset_link) |
| cgroup_migrate_add_src(link->cset, dsct, &mgctx); |
| } |
| spin_unlock_irq(&css_set_lock); |
| |
| /* NULL dst indicates self on default hierarchy */ |
| ret = cgroup_migrate_prepare_dst(&mgctx); |
| if (ret) |
| goto out_finish; |
| |
| spin_lock_irq(&css_set_lock); |
| list_for_each_entry(src_cset, &mgctx.preloaded_src_csets, mg_preload_node) { |
| struct task_struct *task, *ntask; |
| |
| /* all tasks in src_csets need to be migrated */ |
| list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list) |
| cgroup_migrate_add_task(task, &mgctx); |
| } |
| spin_unlock_irq(&css_set_lock); |
| |
| ret = cgroup_migrate_execute(&mgctx); |
| out_finish: |
| cgroup_migrate_finish(&mgctx); |
| percpu_up_write(&cgroup_threadgroup_rwsem); |
| return ret; |
| } |
| |
| /** |
| * cgroup_lock_and_drain_offline - lock cgroup_mutex and drain offlined csses |
| * @cgrp: root of the target subtree |
| * |
| * Because css offlining is asynchronous, userland may try to re-enable a |
| * controller while the previous css is still around. This function grabs |
| * cgroup_mutex and drains the previous css instances of @cgrp's subtree. |
| */ |
| void cgroup_lock_and_drain_offline(struct cgroup *cgrp) |
| __acquires(&cgroup_mutex) |
| { |
| struct cgroup *dsct; |
| struct cgroup_subsys_state *d_css; |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| restart: |
| mutex_lock(&cgroup_mutex); |
| |
| cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) { |
| for_each_subsys(ss, ssid) { |
| struct cgroup_subsys_state *css = cgroup_css(dsct, ss); |
| DEFINE_WAIT(wait); |
| |
| if (!css || !percpu_ref_is_dying(&css->refcnt)) |
| continue; |
| |
| cgroup_get_live(dsct); |
| prepare_to_wait(&dsct->offline_waitq, &wait, |
| TASK_UNINTERRUPTIBLE); |
| |
| mutex_unlock(&cgroup_mutex); |
| schedule(); |
| finish_wait(&dsct->offline_waitq, &wait); |
| |
| cgroup_put(dsct); |
| goto restart; |
| } |
| } |
| } |
| |
| /** |
| * cgroup_save_control - save control masks and dom_cgrp of a subtree |
| * @cgrp: root of the target subtree |
| * |
| * Save ->subtree_control, ->subtree_ss_mask and ->dom_cgrp to the |
| * respective old_ prefixed fields for @cgrp's subtree including @cgrp |
| * itself. |
| */ |
| static void cgroup_save_control(struct cgroup *cgrp) |
| { |
| struct cgroup *dsct; |
| struct cgroup_subsys_state *d_css; |
| |
| cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { |
| dsct->old_subtree_control = dsct->subtree_control; |
| dsct->old_subtree_ss_mask = dsct->subtree_ss_mask; |
| dsct->old_dom_cgrp = dsct->dom_cgrp; |
| } |
| } |
| |
| /** |
| * cgroup_propagate_control - refresh control masks of a subtree |
| * @cgrp: root of the target subtree |
| * |
| * For @cgrp and its subtree, ensure ->subtree_ss_mask matches |
| * ->subtree_control and propagate controller availability through the |
| * subtree so that descendants don't have unavailable controllers enabled. |
| */ |
| static void cgroup_propagate_control(struct cgroup *cgrp) |
| { |
| struct cgroup *dsct; |
| struct cgroup_subsys_state *d_css; |
| |
| cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { |
| dsct->subtree_control &= cgroup_control(dsct); |
| dsct->subtree_ss_mask = |
| cgroup_calc_subtree_ss_mask(dsct->subtree_control, |
| cgroup_ss_mask(dsct)); |
| } |
| } |
| |
| /** |
| * cgroup_restore_control - restore control masks and dom_cgrp of a subtree |
| * @cgrp: root of the target subtree |
| * |
| * Restore ->subtree_control, ->subtree_ss_mask and ->dom_cgrp from the |
| * respective old_ prefixed fields for @cgrp's subtree including @cgrp |
| * itself. |
| */ |
| static void cgroup_restore_control(struct cgroup *cgrp) |
| { |
| struct cgroup *dsct; |
| struct cgroup_subsys_state *d_css; |
| |
| cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) { |
| dsct->subtree_control = dsct->old_subtree_control; |
| dsct->subtree_ss_mask = dsct->old_subtree_ss_mask; |
| dsct->dom_cgrp = dsct->old_dom_cgrp; |
| } |
| } |
| |
| static bool css_visible(struct cgroup_subsys_state *css) |
| { |
| struct cgroup_subsys *ss = css->ss; |
| struct cgroup *cgrp = css->cgroup; |
| |
| if (cgroup_control(cgrp) & (1 << ss->id)) |
| return true; |
| if (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) |
| return false; |
| return cgroup_on_dfl(cgrp) && ss->implicit_on_dfl; |
| } |
| |
| /** |
| * cgroup_apply_control_enable - enable or show csses according to control |
| * @cgrp: root of the target subtree |
| * |
| * Walk @cgrp's subtree and create new csses or make the existing ones |
| * visible. A css is created invisible if it's being implicitly enabled |
| * through dependency. An invisible css is made visible when the userland |
| * explicitly enables it. |
| * |
| * Returns 0 on success, -errno on failure. On failure, csses which have |
| * been processed already aren't cleaned up. The caller is responsible for |
| * cleaning up with cgroup_apply_control_disable(). |
| */ |
| static int cgroup_apply_control_enable(struct cgroup *cgrp) |
| { |
| struct cgroup *dsct; |
| struct cgroup_subsys_state *d_css; |
| struct cgroup_subsys *ss; |
| int ssid, ret; |
| |
| cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { |
| for_each_subsys(ss, ssid) { |
| struct cgroup_subsys_state *css = cgroup_css(dsct, ss); |
| |
| WARN_ON_ONCE(css && percpu_ref_is_dying(&css->refcnt)); |
| |
| if (!(cgroup_ss_mask(dsct) & (1 << ss->id))) |
| continue; |
| |
| if (!css) { |
| css = css_create(dsct, ss); |
| if (IS_ERR(css)) |
| return PTR_ERR(css); |
| } |
| |
| if (css_visible(css)) { |
| ret = css_populate_dir(css); |
| if (ret) |
| return ret; |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * cgroup_apply_control_disable - kill or hide csses according to control |
| * @cgrp: root of the target subtree |
| * |
| * Walk @cgrp's subtree and kill and hide csses so that they match |
| * cgroup_ss_mask() and cgroup_visible_mask(). |
| * |
| * A css is hidden when the userland requests it to be disabled while other |
| * subsystems are still depending on it. The css must not actively control |
| * resources and be in the vanilla state if it's made visible again later. |
| * Controllers which may be depended upon should provide ->css_reset() for |
| * this purpose. |
| */ |
| static void cgroup_apply_control_disable(struct cgroup *cgrp) |
| { |
| struct cgroup *dsct; |
| struct cgroup_subsys_state *d_css; |
| struct cgroup_subsys *ss; |
| int ssid; |
| |
| cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) { |
| for_each_subsys(ss, ssid) { |
| struct cgroup_subsys_state *css = cgroup_css(dsct, ss); |
| |
| WARN_ON_ONCE(css && percpu_ref_is_dying(&css->refcnt)); |
| |
| if (!css) |
| continue; |
| |
| if (css->parent && |
| !(cgroup_ss_mask(dsct) & (1 << ss->id))) { |
| kill_css(css); |
| } else if (!css_visible(css)) { |
| css_clear_dir(css); |
| if (ss->css_reset) |
| ss->css_reset(css); |
| } |
| } |
| } |
| } |
| |
| /** |
| * cgroup_apply_control - apply control mask updates to the subtree |
| * @cgrp: root of the target subtree |
| * |
| * subsystems can be enabled and disabled in a subtree using the following |
| * steps. |
| * |
| * 1. Call cgroup_save_control() to stash the current state. |
| * 2. Update ->subtree_control masks in the subtree as desired. |
| * 3. Call cgroup_apply_control() to apply the changes. |
| * 4. Optionally perform other related operations. |
| * 5. Call cgroup_finalize_control() to finish up. |
| * |
| * This function implements step 3 and propagates the mask changes |
| * throughout @cgrp's subtree, updates csses accordingly and perform |
| * process migrations. |
| */ |
| static int cgroup_apply_control(struct cgroup *cgrp) |
| { |
| int ret; |
| |
| cgroup_propagate_control(cgrp); |
| |
| ret = cgroup_apply_control_enable(cgrp); |
| if (ret) |
| return ret; |
| |
| /* |
| * At this point, cgroup_e_css_by_mask() results reflect the new csses |
| * making the following cgroup_update_dfl_csses() properly update |
| * css associations of all tasks in the subtree. |
| */ |
| ret = cgroup_update_dfl_csses(cgrp); |
| if (ret) |
| return ret; |
| |
| return 0; |
| } |
| |
| /** |
| * cgroup_finalize_control - finalize control mask update |
| * @cgrp: root of the target subtree |
| * @ret: the result of the update |
| * |
| * Finalize control mask update. See cgroup_apply_control() for more info. |
| */ |
| static void cgroup_finalize_control(struct cgroup *cgrp, int ret) |
| { |
| if (ret) { |
| cgroup_restore_control(cgrp); |
| cgroup_propagate_control(cgrp); |
| } |
| |
| cgroup_apply_control_disable(cgrp); |
| } |
| |
| static int cgroup_vet_subtree_control_enable(struct cgroup *cgrp, u16 enable) |
| { |
| u16 domain_enable = enable & ~cgrp_dfl_threaded_ss_mask; |
| |
| /* if nothing is getting enabled, nothing to worry about */ |
| if (!enable) |
| return 0; |
| |
| /* can @cgrp host any resources? */ |
| if (!cgroup_is_valid_domain(cgrp->dom_cgrp)) |
| return -EOPNOTSUPP; |
| |
| /* mixables don't care */ |
| if (cgroup_is_mixable(cgrp)) |
| return 0; |
| |
| if (domain_enable) { |
| /* can't enable domain controllers inside a thread subtree */ |
| if (cgroup_is_thread_root(cgrp) || cgroup_is_threaded(cgrp)) |
| return -EOPNOTSUPP; |
| } else { |
| /* |
| * Threaded controllers can handle internal competitions |
| * and are always allowed inside a (prospective) thread |
| * subtree. |
| */ |
| if (cgroup_can_be_thread_root(cgrp) || cgroup_is_threaded(cgrp)) |
| return 0; |
| } |
| |
| /* |
| * Controllers can't be enabled for a cgroup with tasks to avoid |
| * child cgroups competing against tasks. |
| */ |
| if (cgroup_has_tasks(cgrp)) |
| return -EBUSY; |
| |
| return 0; |
| } |
| |
| /* change the enabled child controllers for a cgroup in the default hierarchy */ |
| static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, |
| char *buf, size_t nbytes, |
| loff_t off) |
| { |
| u16 enable = 0, disable = 0; |
| struct cgroup *cgrp, *child; |
| struct cgroup_subsys *ss; |
| char *tok; |
| int ssid, ret; |
| |
| /* |
| * Parse input - space separated list of subsystem names prefixed |
| * with either + or -. |
| */ |
| buf = strstrip(buf); |
| while ((tok = strsep(&buf, " "))) { |
| if (tok[0] == '\0') |
| continue; |
| do_each_subsys_mask(ss, ssid, ~cgrp_dfl_inhibit_ss_mask) { |
| if (!cgroup_ssid_enabled(ssid) || |
| strcmp(tok + 1, ss->name)) |
| continue; |
| |
| if (*tok == '+') { |
| enable |= 1 << ssid; |
| disable &= ~(1 << ssid); |
| } else if (*tok == '-') { |
| disable |= 1 << ssid; |
| enable &= ~(1 << ssid); |
| } else { |
| return -EINVAL; |
| } |
| break; |
| } while_each_subsys_mask(); |
| if (ssid == CGROUP_SUBSYS_COUNT) |
| return -EINVAL; |
| } |
| |
| cgrp = cgroup_kn_lock_live(of->kn, true); |
| if (!cgrp) |
| return -ENODEV; |
| |
| for_each_subsys(ss, ssid) { |
| if (enable & (1 << ssid)) { |
| if (cgrp->subtree_control & (1 << ssid)) { |
| enable &= ~(1 << ssid); |
| continue; |
| } |
| |
| if (!(cgroup_control(cgrp) & (1 << ssid))) { |
| ret = -ENOENT; |
| goto out_unlock; |
| } |
| } else if (disable & (1 << ssid)) { |
| if (!(cgrp->subtree_control & (1 << ssid))) { |
| disable &= ~(1 << ssid); |
| continue; |
| } |
| |
| /* a child has it enabled? */ |
| cgroup_for_each_live_child(child, cgrp) { |
| if (child->subtree_control & (1 << ssid)) { |
| ret = -EBUSY; |
| goto out_unlock; |
| } |
|