| Message ID | 1388704274-5278-2-git-send-email-john.stultz@linaro.org |
|---|---|
| State | Accepted |
| Commit | 7a06c41cbec33c6dbe7eec575c61986122617408 |
| Headers | show |
On 01/12/2014 10:42 AM, tip-bot for John Stultz wrote: > Commit-ID: 7a06c41cbec33c6dbe7eec575c61986122617408 > Gitweb: http://git.kernel.org/tip/7a06c41cbec33c6dbe7eec575c61986122617408 > Author: John Stultz <john.stultz@linaro.org> > AuthorDate: Thu, 2 Jan 2014 15:11:14 -0800 > Committer: Ingo Molnar <mingo@kernel.org> > CommitDate: Sun, 12 Jan 2014 10:14:00 +0100 > > sched_clock: Disable seqlock lockdep usage in sched_clock() > > Unfortunately the seqlock lockdep enablement 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. > > Acked-by: Linus Torvalds <torvalds@linux-foundation.org> > Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> > Reported-by: Krzysztof Hałasa <khalasa@piap.pl> > Signed-off-by: John Stultz <john.stultz@linaro.org> > Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> > Cc: Willy Tarreau <w@1wt.eu> > Signed-off-by: Peter Zijlstra <peterz@infradead.org> > Link: http://lkml.kernel.org/r/1388704274-5278-2-git-send-email-john.stultz@linaro.org > Signed-off-by: Ingo Molnar <mingo@kernel.org> Hey Ingo, Just wanted to follow up here, since I've still not seen this (and the raw_ renaming patch) submitted to Linus. These address a lockup that triggers on ARM systems if lockdep is enabled and it would be good to get it in before 3.13 is out. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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); }
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 Hałasa <khalasa@piap.pl> Cc: Uwe Kleine-König <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@lists.infradead.org Reported-by: Krzysztof Hałasa <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(-)