linux-kernel - Re: [PATCH] cgroup, cleanup: Delete PF_EXITING checks from cgroup

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Date:	Mon, 31 Aug 2015 15:12:56 +0300
From:	Kirill Tkhai <ktkhai@...n.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	<linux-kernel@...r.kernel.org>, Tejun Heo <tj@...nel.org>,
	Li Zefan <lizefan@...wei.com>
Subject: Re: [PATCH] cgroup, cleanup: Delete PF_EXITING checks from cgroup_exit()
 callbacks

On 31.08.2015 14:53, Peter Zijlstra wrote:
> On Mon, Aug 31, 2015 at 02:49:59PM +0300, Kirill Tkhai wrote:
>> Remove useless checks and outdates commentaries.
> 
> A slightly bigger Changelog could do, maybe also referring to the commit
> that made these checks obsolete.
> 

[PATCH] cgroup, cleanup: Delete PF_EXITING checks from cgroup_exit() callbacks

cgroup_exit() is not called from copy_process() after commit e8604cb43690b781:

	"cgroup: fix spurious lockdep warning in cgroup_exit()", it's only called

from do_exit(). So these checks are useless and commentaries are obsolete. Remove them.

Signed-off-by: Kirill Tkhai <ktkhai@...n.com>
---
 kernel/events/core.c |    8 --------
 kernel/sched/core.c  |    8 --------
 2 files changed, 16 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index ae16867..94bd500 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9219,14 +9219,6 @@ static void perf_cgroup_exit(struct cgroup_subsys_state *css,
 			     struct cgroup_subsys_state *old_css,
 			     struct task_struct *task)
 {
-	/*
-	 * cgroup_exit() is called in the copy_process() failure path.
-	 * Ignore this case since the task hasn't ran yet, this avoids
-	 * trying to poke a half freed task state from generic code.
-	 */
-	if (!(task->flags & PF_EXITING))
-		return;
-
 	task_function_call(task, __perf_cgroup_move, task);
 }
 
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b3386c6..f8509be 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8167,14 +8167,6 @@ static void cpu_cgroup_exit(struct cgroup_subsys_state *css,
 			    struct cgroup_subsys_state *old_css,
 			    struct task_struct *task)
 {
-	/*
-	 * cgroup_exit() is called in the copy_process() failure path.
-	 * Ignore this case since the task hasn't ran yet, this avoids
-	 * trying to poke a half freed task state from generic code.
-	 */
-	if (!(task->flags & PF_EXITING))
-		return;
-
 	sched_move_task(task);
 }
 

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