linux-kernel - [tip:sched/urgent] sched/cputime: Always set tsk->vtime_snap

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Message-ID: <tip-9fa57cf5a5c4aed1e45879b335fe433048709327@git.kernel.org>
Date:   Wed, 5 Jul 2017 03:28:36 -0700
From:   tip-bot for Frederic Weisbecker <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     lcapitulino@...hat.com, riel@...hat.com, hpa@...or.com,
        mingo@...nel.org, tglx@...utronix.de, fweisbec@...il.com,
        torvalds@...ux-foundation.org, peterz@...radead.org,
        linux-kernel@...r.kernel.org, kernellwp@...il.com
Subject: [tip:sched/urgent] sched/cputime: Always set tsk->vtime_snap_whence
 after accounting vtime

Commit-ID:  9fa57cf5a5c4aed1e45879b335fe433048709327
Gitweb:     http://git.kernel.org/tip/9fa57cf5a5c4aed1e45879b335fe433048709327
Author:     Frederic Weisbecker <fweisbec@...il.com>
AuthorDate: Thu, 29 Jun 2017 19:15:08 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 5 Jul 2017 09:54:14 +0200

sched/cputime: Always set tsk->vtime_snap_whence after accounting vtime

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@...hat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Rik van Riel <riel@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Wanpeng Li <kernellwp@...il.com>
Link: http://lkml.kernel.org/r/1498756511-11714-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 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 5adc896..ab68927 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);
 }