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| author | Ahmed S. Darwish <a.darwish@linutronix.de> | 2020-08-27 13:40:37 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-09-10 11:19:28 +0200 |
| commit | 58faf20a086bd34f91983609e26eac3d5fe76be3 (patch) | |
| tree | 4520a46dbe31af3639f326c0697ccd16ee7c161b /kernel/time | |
| parent | 96a16f45aed89cf024606a11679b0609d09552c7 (diff) | |
| download | linux-stable-58faf20a086bd34f91983609e26eac3d5fe76be3.tar.gz linux-stable-58faf20a086bd34f91983609e26eac3d5fe76be3.tar.bz2 linux-stable-58faf20a086bd34f91983609e26eac3d5fe76be3.zip | |
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.c | 2 |
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; } |