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authorAhmed S. Darwish <a.darwish@linutronix.de>2020-08-27 13:40:37 +0200
committerPeter Zijlstra <peterz@infradead.org>2020-09-10 11:19:28 +0200
commit58faf20a086bd34f91983609e26eac3d5fe76be3 (patch)
tree4520a46dbe31af3639f326c0697ccd16ee7c161b /kernel/time
parent96a16f45aed89cf024606a11679b0609d09552c7 (diff)
time/sched_clock: Use raw_read_seqcount_latch() during suspend
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 has one read memory barrier less than the currently used raw_read_seqcount() API. Use raw_read_seqcount_latch() for the suspend path. Commit aadd6e5caaac ("time/sched_clock: Use raw_read_seqcount_latch()") missed changing that instance of raw_read_seqcount(). References: 1809bfa44e10 ("timers, sched/clock: Avoid deadlock during read from NMI") Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200715092345.GA231464@debian-buster-darwi.lab.linutronix.de
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 1c03eec6ca9b..8c6b5febd7a0 100644
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -258,7 +258,7 @@ void __init generic_sched_clock_init(void)
*/
static u64 notrace suspended_sched_clock_read(void)
{
- unsigned int seq = raw_read_seqcount(&cd.seq);
+ unsigned int seq = raw_read_seqcount_latch(&cd.seq);
return cd.read_data[seq & 1].epoch_cyc;
}