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authorAhmed S. Darwish <a.darwish@linutronix.de>2020-07-16 13:11:25 +0800
committerWill Deacon <will@kernel.org>2020-07-20 11:50:47 +0100
commitaadd6e5caaacd6feca9691ba30536e7de5a7d152 (patch)
treef787a5427d498335af8c1abbb1b1ff3091f18624 /kernel/time
parent1b86abc1c645ad5c9c7bf70910cb3ce73939d2d7 (diff)
time/sched_clock: Use raw_read_seqcount_latch()
sched_clock uses seqcount_t latching to switch between two storage places protected by the sequence counter. This allows it to have interruptible, NMI-safe, seqcount_t write side critical sections. Since 7fc26327b756 ("seqlock: Introduce raw_read_seqcount_latch()"), raw_read_seqcount_latch() became the standardized way for seqcount_t latch read paths. Due to the dependent load, it also has one read memory barrier less than the currently used raw_read_seqcount() API. Use raw_read_seqcount_latch() for the seqcount_t latch read path. Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Signed-off-by: Leo Yan <leo.yan@linaro.org> Link: https://lkml.kernel.org/r/20200625085745.GD117543@hirez.programming.kicks-ass.net Link: https://lkml.kernel.org/r/20200715092345.GA231464@debian-buster-darwi.lab.linutronix.de Link: https://lore.kernel.org/r/20200716051130.4359-3-leo.yan@linaro.org References: 1809bfa44e10 ("timers, sched/clock: Avoid deadlock during read from NMI") Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/sched_clock.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index 0acaadc3156c..0deaf4b79fb4 100644
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -70,7 +70,7 @@ static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift)
struct clock_read_data *sched_clock_read_begin(unsigned int *seq)
{
- *seq = raw_read_seqcount(&cd.seq);
+ *seq = raw_read_seqcount_latch(&cd.seq);
return cd.read_data + (*seq & 1);
}