From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Thu, 29 Jun 2017 19:15:08 +0200
Subject: [PATCH] sched/cputime: Always set tsk->vtime_snap_whence after
 accounting vtime
References: bnc#1060662 bnc#978907
Patch-mainline: 4.12.4
Git-commit: 9fa57cf5a5c4aed1e45879b335fe433048709327

commit 9fa57cf5a5c4aed1e45879b335fe433048709327 upstream.

Even though it doesn't have functional consequences, setting
the task's new context state after we actually accounted the pending
vtime from the old context state makes more sense from a review
perspective.

vtime_user_exit() is the only function that doesn't follow that rule
and that can bug the reviewer for a little while until he realizes there
is no reason for this special case.

Tested-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wanpeng Li <kernellwp@gmail.com>
Link: http://lkml.kernel.org/r/1498756511-11714-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 kernel/sched/cputime.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 5e080caf125e..db7ef1037f39 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -736,9 +736,9 @@ void vtime_user_enter(struct task_struct *tsk)
 void vtime_user_exit(struct task_struct *tsk)
 {
 	write_seqcount_begin(&tsk->vtime_seqcount);
-	tsk->vtime_snap_whence = VTIME_SYS;
 	if (vtime_delta(tsk))
 		account_user_time(tsk, get_vtime_delta(tsk));
+	tsk->vtime_snap_whence = VTIME_SYS;
 	write_seqcount_end(&tsk->vtime_seqcount);
 }
 
-- 
2.14.2