cgroup: consolidate cgroup_attach_task() and cgroup_attach_proc()
These two functions share most of the code.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 54689fc..04fa2ab 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -59,7 +59,7 @@
#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
#include <linux/eventfd.h>
#include <linux/poll.h>
-#include <linux/flex_array.h> /* used in cgroup_attach_proc */
+#include <linux/flex_array.h> /* used in cgroup_attach_task */
#include <linux/kthread.h>
#include <linux/atomic.h>
@@ -1944,82 +1944,6 @@
}
/**
- * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp'
- * @cgrp: the cgroup the task is attaching to
- * @tsk: the task to be attached
- *
- * Call with cgroup_mutex and threadgroup locked. May take task_lock of
- * @tsk during call.
- */
-int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
-{
- int retval = 0;
- struct cgroup_subsys *ss, *failed_ss = NULL;
- struct cgroup *oldcgrp;
- struct cgroupfs_root *root = cgrp->root;
- struct cgroup_taskset tset = { };
- struct css_set *newcg;
-
- /* @tsk either already exited or can't exit until the end */
- if (tsk->flags & PF_EXITING)
- return -ESRCH;
-
- /* Nothing to do if the task is already in that cgroup */
- oldcgrp = task_cgroup_from_root(tsk, root);
- if (cgrp == oldcgrp)
- return 0;
-
- tset.single.task = tsk;
- tset.single.cgrp = oldcgrp;
-
- for_each_subsys(root, ss) {
- if (ss->can_attach) {
- retval = ss->can_attach(cgrp, &tset);
- if (retval) {
- /*
- * Remember on which subsystem the can_attach()
- * failed, so that we only call cancel_attach()
- * against the subsystems whose can_attach()
- * succeeded. (See below)
- */
- failed_ss = ss;
- goto out;
- }
- }
- }
-
- newcg = find_css_set(tsk->cgroups, cgrp);
- if (!newcg) {
- retval = -ENOMEM;
- goto out;
- }
-
- cgroup_task_migrate(cgrp, oldcgrp, tsk, newcg);
-
- for_each_subsys(root, ss) {
- if (ss->attach)
- ss->attach(cgrp, &tset);
- }
-
-out:
- if (retval) {
- for_each_subsys(root, ss) {
- if (ss == failed_ss)
- /*
- * This subsystem was the one that failed the
- * can_attach() check earlier, so we don't need
- * to call cancel_attach() against it or any
- * remaining subsystems.
- */
- break;
- if (ss->cancel_attach)
- ss->cancel_attach(cgrp, &tset);
- }
- }
- return retval;
-}
-
-/**
* cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
* @from: attach to all cgroups of a given task
* @tsk: the task to be attached
@@ -2033,7 +1957,7 @@
for_each_active_root(root) {
struct cgroup *from_cg = task_cgroup_from_root(from, root);
- retval = cgroup_attach_task(from_cg, tsk);
+ retval = cgroup_attach_task(from_cg, tsk, false);
if (retval)
break;
}
@@ -2044,21 +1968,22 @@
EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
/**
- * cgroup_attach_proc - attach all threads in a threadgroup to a cgroup
+ * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
* @cgrp: the cgroup to attach to
- * @leader: the threadgroup leader task_struct of the group to be attached
+ * @tsk: the task or the leader of the threadgroup to be attached
+ * @threadgroup: attach the whole threadgroup?
*
* Call holding cgroup_mutex and the group_rwsem of the leader. Will take
- * task_lock of each thread in leader's threadgroup individually in turn.
+ * task_lock of @tsk or each thread in the threadgroup individually in turn.
*/
-static int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
+int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk,
+ bool threadgroup)
{
int retval, i, group_size;
struct cgroup_subsys *ss, *failed_ss = NULL;
- /* guaranteed to be initialized later, but the compiler needs this */
struct cgroupfs_root *root = cgrp->root;
/* threadgroup list cursor and array */
- struct task_struct *tsk;
+ struct task_struct *leader = tsk;
struct task_and_cgroup *tc;
struct flex_array *group;
struct cgroup_taskset tset = { };
@@ -2070,7 +1995,10 @@
* group - group_rwsem prevents new threads from appearing, and if
* threads exit, this will just be an over-estimate.
*/
- group_size = get_nr_threads(leader);
+ if (threadgroup)
+ group_size = get_nr_threads(tsk);
+ else
+ group_size = 1;
/* flex_array supports very large thread-groups better than kmalloc. */
group = flex_array_alloc(sizeof(*tc), group_size, GFP_KERNEL);
if (!group)
@@ -2080,7 +2008,6 @@
if (retval)
goto out_free_group_list;
- tsk = leader;
i = 0;
/*
* Prevent freeing of tasks while we take a snapshot. Tasks that are
@@ -2109,6 +2036,9 @@
retval = flex_array_put(group, i, &ent, GFP_ATOMIC);
BUG_ON(retval != 0);
i++;
+
+ if (!threadgroup)
+ break;
} while_each_thread(leader, tsk);
rcu_read_unlock();
/* remember the number of threads in the array for later. */
@@ -2262,9 +2192,10 @@
put_task_struct(tsk);
goto retry_find_task;
}
- ret = cgroup_attach_proc(cgrp, tsk);
- } else
- ret = cgroup_attach_task(cgrp, tsk);
+ }
+
+ ret = cgroup_attach_task(cgrp, tsk, threadgroup);
+
threadgroup_unlock(tsk);
put_task_struct(tsk);
