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From: john.stultz@linaro.org (John Stultz)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/2] sched_clock: Disable seqlock lockdep usage in sched_clock
Date: Thu,  2 Jan 2014 15:11:14 -0800
Message-ID: <1388704274-5278-2-git-send-email-john.stultz@linaro.org> (raw)
In-Reply-To: <1388704274-5278-1-git-send-email-john.stultz@linaro.org>

Unforunately the seqlock lockdep enablmenet can't be used
in sched_clock, since the lockdep infrastructure eventually
calls into sched_clock, which causes a deadlock.

Thus, this patch changes all generic sched_clock usage
to use the raw_* methods.

Cc: Krzysztof Ha?asa <khalasa@piap.pl>
Cc: Uwe Kleine-K?nig <u.kleine-koenig@pengutronix.de>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Ingo Molnar <mingo@kernel.org>,
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-arm-kernel at lists.infradead.org
Reported-by: Krzysztof Ha?asa <khalasa@piap.pl>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 kernel/time/sched_clock.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index 68b7993..0abb364 100644
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -74,7 +74,7 @@ unsigned long long notrace sched_clock(void)
 		return cd.epoch_ns;
 
 	do {
-		seq = read_seqcount_begin(&cd.seq);
+		seq = raw_read_seqcount_begin(&cd.seq);
 		epoch_cyc = cd.epoch_cyc;
 		epoch_ns = cd.epoch_ns;
 	} while (read_seqcount_retry(&cd.seq, seq));
@@ -99,10 +99,10 @@ static void notrace update_sched_clock(void)
 			  cd.mult, cd.shift);
 
 	raw_local_irq_save(flags);
-	write_seqcount_begin(&cd.seq);
+	raw_write_seqcount_begin(&cd.seq);
 	cd.epoch_ns = ns;
 	cd.epoch_cyc = cyc;
-	write_seqcount_end(&cd.seq);
+	raw_write_seqcount_end(&cd.seq);
 	raw_local_irq_restore(flags);
 }
 
-- 
1.8.3.2

  reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-31 10:37 v3.13-rc6+ regression (ARM board) Krzysztof Hałasa
2013-12-31 10:45 ` Willy Tarreau
2014-01-02 10:02   ` Krzysztof Hałasa
2014-01-02 10:14     ` Uwe Kleine-König
2014-01-02 12:07       ` Krzysztof Hałasa
2014-01-02 19:38         ` Linus Torvalds
2014-01-02 20:03           ` John Stultz
2014-01-02 20:30             ` John Stultz
2014-01-02 20:42               ` Stephen Boyd
2014-01-02 20:52                 ` John Stultz
2014-01-02 20:43               ` Linus Torvalds
2014-01-02 21:34                 ` John Stultz
2014-01-02 21:54                   ` [PATCH] sched_clock: Disable seqlock lockdep usage in sched_clock John Stultz
2014-01-02 22:15                     ` Linus Torvalds
2014-01-02 22:21                       ` John Stultz
2014-01-02 23:11                         ` [PATCH 1/2] seqlock: Use raw_ prefix instead of _no_lockdep John Stultz
2014-01-02 23:11                           ` John Stultz [this message]
2014-01-03  0:46                             ` [PATCH 2/2] sched_clock: Disable seqlock lockdep usage in sched_clock Stephen Boyd
2014-01-03  6:05                             ` Krzysztof Hałasa
2014-01-03  0:46                           ` [PATCH 1/2] seqlock: Use raw_ prefix instead of _no_lockdep Stephen Boyd
2014-01-03  0:50                           ` Linus Torvalds
2014-01-04  0:28                             ` John Stultz
2014-01-06 10:10                               ` Peter Zijlstra
2014-01-03  6:01           ` v3.13-rc6+ regression (ARM board) Krzysztof Hałasa

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