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authorMandeep Singh Baines <msb@chromium.org>2011-12-21 20:18:36 -0800
committerTejun Heo <tj@kernel.org>2011-12-22 07:32:57 -0800
commitb07ef7741122a83575499c11417e514877941e76 (patch)
treeba7fa1298320cce6ffef59e7865ef4fecbd23af1 /kernel/cgroup.c
parent026085ef5ae07c3197f2baacc091ce067b86ed11 (diff)
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.c11
1 files changed, 2 insertions, 9 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 82288088f6a..a85a7002ca3 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;