linux-kernel - [tip:sched/core] sched/core: Reset RQCF_ACT

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Date:   Sat, 14 Jan 2017 04:41:15 -0800
From:   tip-bot for Matt Fleming <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     torvalds@...ux-foundation.org, hpa@...or.com,
        umgwanakikbuti@...il.com, efault@....de, yuyang.du@...el.com,
        sergey.senozhatsky.work@...il.com, peterz@...radead.org,
        fweisbec@...il.com, pmladek@...e.com, luca.abeni@...tn.it,
        mgorman@...hsingularity.net, byungchul.park@....com,
        linux-kernel@...r.kernel.org, wanpeng.li@...mail.com,
        tglx@...utronix.de, riel@...hat.com, jack@...e.cz,
        mingo@...nel.org, matt@...eblueprint.co.uk
Subject: [tip:sched/core] sched/core: Reset RQCF_ACT_SKIP before unpinning
 rq->lock

Commit-ID:  92509b732baf14c59ca702307270cfaa3a585ae7
Gitweb:     http://git.kernel.org/tip/92509b732baf14c59ca702307270cfaa3a585ae7
Author:     Matt Fleming <matt@...eblueprint.co.uk>
AuthorDate: Wed, 21 Sep 2016 14:38:11 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Sat, 14 Jan 2017 11:29:31 +0100

sched/core: Reset RQCF_ACT_SKIP before unpinning rq->lock

rq_clock() is called from sched_info_{depart,arrive}() after resetting
RQCF_ACT_SKIP but prior to a call to update_rq_clock().

In preparation for pending patches that check whether the rq clock has
been updated inside of a pin context before rq_clock() is called, move
the reset of rq->clock_skip_update immediately before unpinning the rq
lock.

This will avoid the new warnings which check if update_rq_clock() is
being actively skipped.

Signed-off-by: Matt Fleming <matt@...eblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Byungchul Park <byungchul.park@....com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Jan Kara <jack@...e.cz>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Luca Abeni <luca.abeni@...tn.it>
Cc: Mel Gorman <mgorman@...hsingularity.net>
Cc: Mike Galbraith <efault@....de>
Cc: Mike Galbraith <umgwanakikbuti@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Petr Mladek <pmladek@...e.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Wanpeng Li <wanpeng.li@...mail.com>
Cc: Yuyang Du <yuyang.du@...el.com>
Link: http://lkml.kernel.org/r/20160921133813.31976-6-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 41df935..311460b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2887,6 +2887,9 @@ context_switch(struct rq *rq, struct task_struct *prev,
 		prev->active_mm = NULL;
 		rq->prev_mm = oldmm;
 	}
+
+	rq->clock_skip_update = 0;
+
 	/*
 	 * Since the runqueue lock will be released by the next
 	 * task (which is an invalid locking op but in the case
@@ -3392,7 +3395,6 @@ static void __sched notrace __schedule(bool preempt)
 	next = pick_next_task(rq, prev, &rf);
 	clear_tsk_need_resched(prev);
 	clear_preempt_need_resched();
-	rq->clock_skip_update = 0;
 
 	if (likely(prev != next)) {
 		rq->nr_switches++;
@@ -3402,6 +3404,7 @@ static void __sched notrace __schedule(bool preempt)
 		trace_sched_switch(preempt, prev, next);
 		rq = context_switch(rq, prev, next, &rf); /* unlocks the rq */
 	} else {
+		rq->clock_skip_update = 0;
 		rq_unpin_lock(rq, &rf);
 		raw_spin_unlock_irq(&rq->lock);
 	}