| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Debug controller |
| * |
| * WARNING: This controller is for cgroup core debugging only. |
| * Its interfaces are unstable and subject to changes at any time. |
| */ |
| #include <linux/ctype.h> |
| #include <linux/mm.h> |
| #include <linux/slab.h> |
| |
| #include "cgroup-internal.h" |
| |
| static struct cgroup_subsys_state * |
| debug_css_alloc(struct cgroup_subsys_state *parent_css) |
| { |
| struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); |
| |
| if (!css) |
| return ERR_PTR(-ENOMEM); |
| |
| return css; |
| } |
| |
| static void debug_css_free(struct cgroup_subsys_state *css) |
| { |
| kfree(css); |
| } |
| |
| /* |
| * debug_taskcount_read - return the number of tasks in a cgroup. |
| * @cgrp: the cgroup in question |
| */ |
| static u64 debug_taskcount_read(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| return cgroup_task_count(css->cgroup); |
| } |
| |
| static int current_css_set_read(struct seq_file *seq, void *v) |
| { |
| struct kernfs_open_file *of = seq->private; |
| struct css_set *cset; |
| struct cgroup_subsys *ss; |
| struct cgroup_subsys_state *css; |
| int i, refcnt; |
| |
| if (!cgroup_kn_lock_live(of->kn, false)) |
| return -ENODEV; |
| |
| spin_lock_irq(&css_set_lock); |
| rcu_read_lock(); |
| cset = task_css_set(current); |
| refcnt = refcount_read(&cset->refcount); |
| seq_printf(seq, "css_set %pK %d", cset, refcnt); |
| if (refcnt > cset->nr_tasks) |
| seq_printf(seq, " +%d", refcnt - cset->nr_tasks); |
| seq_puts(seq, "\n"); |
| |
| /* |
| * Print the css'es stored in the current css_set. |
| */ |
| for_each_subsys(ss, i) { |
| css = cset->subsys[ss->id]; |
| if (!css) |
| continue; |
| seq_printf(seq, "%2d: %-4s\t- %lx[%d]\n", ss->id, ss->name, |
| (unsigned long)css, css->id); |
| } |
| rcu_read_unlock(); |
| spin_unlock_irq(&css_set_lock); |
| cgroup_kn_unlock(of->kn); |
| return 0; |
| } |
| |
| static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, |
| struct cftype *cft) |
| { |
| u64 count; |
| |
| rcu_read_lock(); |
| count = refcount_read(&task_css_set(current)->refcount); |
| rcu_read_unlock(); |
| return count; |
| } |
| |
| static int current_css_set_cg_links_read(struct seq_file *seq, void *v) |
| { |
| struct cgrp_cset_link *link; |
| struct css_set *cset; |
| char *name_buf; |
| |
| name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); |
| if (!name_buf) |
| return -ENOMEM; |
| |
| spin_lock_irq(&css_set_lock); |
| rcu_read_lock(); |
| cset = task_css_set(current); |
| list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
| struct cgroup *c = link->cgrp; |
| |
| cgroup_name(c, name_buf, NAME_MAX + 1); |
| seq_printf(seq, "Root %d group %s\n", |
| c->root->hierarchy_id, name_buf); |
| } |
| rcu_read_unlock(); |
| spin_unlock_irq(&css_set_lock); |
| kfree(name_buf); |
| return 0; |
| } |
| |
| #define MAX_TASKS_SHOWN_PER_CSS 25 |
| static int cgroup_css_links_read(struct seq_file *seq, void *v) |
| { |
| struct cgroup_subsys_state *css = seq_css(seq); |
| struct cgrp_cset_link *link; |
| int dead_cnt = 0, extra_refs = 0, threaded_csets = 0; |
| |
| spin_lock_irq(&css_set_lock); |
| |
| list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
| struct css_set *cset = link->cset; |
| struct task_struct *task; |
| int count = 0; |
| int refcnt = refcount_read(&cset->refcount); |
| |
| /* |
| * Print out the proc_cset and threaded_cset relationship |
| * and highlight difference between refcount and task_count. |
| */ |
| seq_printf(seq, "css_set %pK", cset); |
| if (rcu_dereference_protected(cset->dom_cset, 1) != cset) { |
| threaded_csets++; |
| seq_printf(seq, "=>%pK", cset->dom_cset); |
| } |
| if (!list_empty(&cset->threaded_csets)) { |
| struct css_set *tcset; |
| int idx = 0; |
| |
| list_for_each_entry(tcset, &cset->threaded_csets, |
| threaded_csets_node) { |
| seq_puts(seq, idx ? "," : "<="); |
| seq_printf(seq, "%pK", tcset); |
| idx++; |
| } |
| } else { |
| seq_printf(seq, " %d", refcnt); |
| if (refcnt - cset->nr_tasks > 0) { |
| int extra = refcnt - cset->nr_tasks; |
| |
| seq_printf(seq, " +%d", extra); |
| /* |
| * Take out the one additional reference in |
| * init_css_set. |
| */ |
| if (cset == &init_css_set) |
| extra--; |
| extra_refs += extra; |
| } |
| } |
| seq_puts(seq, "\n"); |
| |
| list_for_each_entry(task, &cset->tasks, cg_list) { |
| if (count++ <= MAX_TASKS_SHOWN_PER_CSS) |
| seq_printf(seq, " task %d\n", |
| task_pid_vnr(task)); |
| } |
| |
| list_for_each_entry(task, &cset->mg_tasks, cg_list) { |
| if (count++ <= MAX_TASKS_SHOWN_PER_CSS) |
| seq_printf(seq, " task %d\n", |
| task_pid_vnr(task)); |
| } |
| /* show # of overflowed tasks */ |
| if (count > MAX_TASKS_SHOWN_PER_CSS) |
| seq_printf(seq, " ... (%d)\n", |
| count - MAX_TASKS_SHOWN_PER_CSS); |
| |
| if (cset->dead) { |
| seq_puts(seq, " [dead]\n"); |
| dead_cnt++; |
| } |
| |
| WARN_ON(count != cset->nr_tasks); |
| } |
| spin_unlock_irq(&css_set_lock); |
| |
| if (!dead_cnt && !extra_refs && !threaded_csets) |
| return 0; |
| |
| seq_puts(seq, "\n"); |
| if (threaded_csets) |
| seq_printf(seq, "threaded css_sets = %d\n", threaded_csets); |
| if (extra_refs) |
| seq_printf(seq, "extra references = %d\n", extra_refs); |
| if (dead_cnt) |
| seq_printf(seq, "dead css_sets = %d\n", dead_cnt); |
| |
| return 0; |
| } |
| |
| static int cgroup_subsys_states_read(struct seq_file *seq, void *v) |
| { |
| struct kernfs_open_file *of = seq->private; |
| struct cgroup *cgrp; |
| struct cgroup_subsys *ss; |
| struct cgroup_subsys_state *css; |
| char pbuf[16]; |
| int i; |
| |
| cgrp = cgroup_kn_lock_live(of->kn, false); |
| if (!cgrp) |
| return -ENODEV; |
| |
| for_each_subsys(ss, i) { |
| css = rcu_dereference_check(cgrp->subsys[ss->id], true); |
| if (!css) |
| continue; |
| |
| pbuf[0] = '\0'; |
| |
| /* Show the parent CSS if applicable*/ |
| if (css->parent) |
| snprintf(pbuf, sizeof(pbuf) - 1, " P=%d", |
| css->parent->id); |
| seq_printf(seq, "%2d: %-4s\t- %lx[%d] %d%s\n", ss->id, ss->name, |
| (unsigned long)css, css->id, |
| atomic_read(&css->online_cnt), pbuf); |
| } |
| |
| cgroup_kn_unlock(of->kn); |
| return 0; |
| } |
| |
| static void cgroup_masks_read_one(struct seq_file *seq, const char *name, |
| u16 mask) |
| { |
| struct cgroup_subsys *ss; |
| int ssid; |
| bool first = true; |
| |
| seq_printf(seq, "%-17s: ", name); |
| for_each_subsys(ss, ssid) { |
| if (!(mask & (1 << ssid))) |
| continue; |
| if (!first) |
| seq_puts(seq, ", "); |
| seq_puts(seq, ss->name); |
| first = false; |
| } |
| seq_putc(seq, '\n'); |
| } |
| |
| static int cgroup_masks_read(struct seq_file *seq, void *v) |
| { |
| struct kernfs_open_file *of = seq->private; |
| struct cgroup *cgrp; |
| |
| cgrp = cgroup_kn_lock_live(of->kn, false); |
| if (!cgrp) |
| return -ENODEV; |
| |
| cgroup_masks_read_one(seq, "subtree_control", cgrp->subtree_control); |
| cgroup_masks_read_one(seq, "subtree_ss_mask", cgrp->subtree_ss_mask); |
| |
| cgroup_kn_unlock(of->kn); |
| return 0; |
| } |
| |
| static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) |
| { |
| return (!cgroup_is_populated(css->cgroup) && |
| !css_has_online_children(&css->cgroup->self)); |
| } |
| |
| static struct cftype debug_legacy_files[] = { |
| { |
| .name = "taskcount", |
| .read_u64 = debug_taskcount_read, |
| }, |
| |
| { |
| .name = "current_css_set", |
| .seq_show = current_css_set_read, |
| .flags = CFTYPE_ONLY_ON_ROOT, |
| }, |
| |
| { |
| .name = "current_css_set_refcount", |
| .read_u64 = current_css_set_refcount_read, |
| .flags = CFTYPE_ONLY_ON_ROOT, |
| }, |
| |
| { |
| .name = "current_css_set_cg_links", |
| .seq_show = current_css_set_cg_links_read, |
| .flags = CFTYPE_ONLY_ON_ROOT, |
| }, |
| |
| { |
| .name = "cgroup_css_links", |
| .seq_show = cgroup_css_links_read, |
| }, |
| |
| { |
| .name = "cgroup_subsys_states", |
| .seq_show = cgroup_subsys_states_read, |
| }, |
| |
| { |
| .name = "cgroup_masks", |
| .seq_show = cgroup_masks_read, |
| }, |
| |
| { |
| .name = "releasable", |
| .read_u64 = releasable_read, |
| }, |
| |
| { } /* terminate */ |
| }; |
| |
| static struct cftype debug_files[] = { |
| { |
| .name = "taskcount", |
| .read_u64 = debug_taskcount_read, |
| }, |
| |
| { |
| .name = "current_css_set", |
| .seq_show = current_css_set_read, |
| .flags = CFTYPE_ONLY_ON_ROOT, |
| }, |
| |
| { |
| .name = "current_css_set_refcount", |
| .read_u64 = current_css_set_refcount_read, |
| .flags = CFTYPE_ONLY_ON_ROOT, |
| }, |
| |
| { |
| .name = "current_css_set_cg_links", |
| .seq_show = current_css_set_cg_links_read, |
| .flags = CFTYPE_ONLY_ON_ROOT, |
| }, |
| |
| { |
| .name = "css_links", |
| .seq_show = cgroup_css_links_read, |
| }, |
| |
| { |
| .name = "csses", |
| .seq_show = cgroup_subsys_states_read, |
| }, |
| |
| { |
| .name = "masks", |
| .seq_show = cgroup_masks_read, |
| }, |
| |
| { } /* terminate */ |
| }; |
| |
| struct cgroup_subsys debug_cgrp_subsys = { |
| .css_alloc = debug_css_alloc, |
| .css_free = debug_css_free, |
| .legacy_cftypes = debug_legacy_files, |
| }; |
| |
| /* |
| * On v2, debug is an implicit controller enabled by "cgroup_debug" boot |
| * parameter. |
| */ |
| void __init enable_debug_cgroup(void) |
| { |
| debug_cgrp_subsys.dfl_cftypes = debug_files; |
| debug_cgrp_subsys.implicit_on_dfl = true; |
| debug_cgrp_subsys.threaded = true; |
| } |