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| author | Mandeep Singh Baines <msb@chromium.org> | 2011-12-21 20:18:36 -0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2011-12-22 07:32:57 -0800 |
| commit | b07ef7741122a83575499c11417e514877941e76 (patch) | |
| tree | ba7fa1298320cce6ffef59e7865ef4fecbd23af1 /kernel/cgroup.c | |
| parent | 026085ef5ae07c3197f2baacc091ce067b86ed11 (diff) | |
| download | lwn-b07ef7741122a83575499c11417e514877941e76.tar.gz lwn-b07ef7741122a83575499c11417e514877941e76.zip | |
cgroup: remove redundant get/put of task struct
threadgroup_lock() guarantees that the target threadgroup will
remain stable - no new task will be added, no new PF_EXITING
will be set and exec won't happen.
Changes in V2:
* https://lkml.org/lkml/2011/12/20/369 (Tejun Heo)
* Undo incorrect removal of get/put from attach_task_by_pid()
* Author
* Remove a comment which is made stale by this change
Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: containers@lists.linux-foundation.org
Cc: cgroups@vger.kernel.org
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Menage <paul@paulmenage.org>
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 11 |
1 files changed, 2 insertions, 9 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 82288088f6a5..a85a7002ca33 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2116,7 +2116,7 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) retval = -EAGAIN; goto out_free_group_list; } - /* take a reference on each task in the group to go in the array. */ + tsk = leader; i = nr_migrating_tasks = 0; do { @@ -2128,7 +2128,6 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) /* as per above, nr_threads may decrease, but not increase. */ BUG_ON(i >= group_size); - get_task_struct(tsk); /* * saying GFP_ATOMIC has no effect here because we did prealloc * earlier, but it's good form to communicate our expectations. @@ -2150,7 +2149,7 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) /* methods shouldn't be called if no task is actually migrating */ retval = 0; if (!nr_migrating_tasks) - goto out_put_tasks; + goto out_free_group_list; /* * step 1: check that we can legitimately attach to the cgroup. @@ -2234,12 +2233,6 @@ out_cancel_attach: ss->cancel_attach(ss, cgrp, &tset); } } -out_put_tasks: - /* clean up the array of referenced threads in the group. */ - for (i = 0; i < group_size; i++) { - tc = flex_array_get(group, i); - put_task_struct(tc->task); - } out_free_group_list: flex_array_free(group); return retval; |