| Message ID | 1388704274-5278-2-git-send-email-john.stultz@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 01/02/14 15:11, John Stultz wrote: > Unforunately the seqlock lockdep enablmenet can't be used s/Unforunately/Unfortunately/ s/enablmenet/enablement/ > 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> Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
John Stultz <john.stultz@linaro.org> writes: > 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. These two patches fix the problem. Thanks to all involved.
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(-)