From: "tip-bot2 for Ahmed S. Darwish" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: "Ahmed S. Darwish" <a.darwish@linutronix.de>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
x86 <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: [tip: locking/core] time/sched_clock: Use raw_read_seqcount_latch() during suspend
Date: Thu, 10 Sep 2020 15:08:29 -0000 [thread overview]
Message-ID: <159975050909.20229.15551175096840400557.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20200715092345.GA231464@debian-buster-darwi.lab.linutronix.de>
The following commit has been merged into the locking/core branch of tip:
Commit-ID: 58faf20a086bd34f91983609e26eac3d5fe76be3
Gitweb: https://git.kernel.org/tip/58faf20a086bd34f91983609e26eac3d5fe76be3
Author: Ahmed S. Darwish <a.darwish@linutronix.de>
AuthorDate: Thu, 27 Aug 2020 13:40:37 +02:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 10 Sep 2020 11:19:28 +02:00
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
---
kernel/time/sched_clock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index 1c03eec..8c6b5fe 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;
}
next prev parent reply other threads:[~2020-09-10 19:28 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-15 2:05 [PATCH v2 0/6] arm64: perf: Proper cap_user_time* support Leo Yan
2020-07-15 2:05 ` [PATCH v2 1/6] sched_clock: Expose struct clock_read_data Leo Yan
2020-07-15 5:56 ` Ahmed S. Darwish
2020-07-15 6:54 ` Leo Yan
2020-07-15 7:21 ` Ahmed S. Darwish
2020-07-15 8:12 ` Peter Zijlstra
2020-07-15 8:14 ` peterz
2020-07-15 9:23 ` Ahmed S. Darwish
2020-07-15 9:52 ` Peter Zijlstra
2020-07-15 11:59 ` [PATCH] time/sched_clock: Use raw_read_seqcount_latch() Ahmed S. Darwish
2020-07-15 15:29 ` Leo Yan
2020-07-15 15:58 ` Peter Zijlstra
2020-07-16 5:22 ` Leo Yan
2020-09-10 15:08 ` tip-bot2 for Ahmed S. Darwish [this message]
2020-07-15 2:05 ` [PATCH v2 2/6] arm64: perf: Implement correct cap_user_time Leo Yan
2020-07-15 8:38 ` Peter Zijlstra
2020-07-15 15:39 ` Leo Yan
2020-07-15 2:05 ` [PATCH v2 3/6] arm64: perf: Only advertise cap_user_time for arch_timer Leo Yan
2020-07-15 2:05 ` [PATCH v2 4/6] perf: Add perf_event_mmap_page::cap_user_time_short ABI Leo Yan
2020-07-15 2:05 ` [PATCH v2 5/6] arm64: perf: Add cap_user_time_short Leo Yan
2020-07-15 2:05 ` [PATCH v2 6/6] tools headers UAPI: Update tools's copy of linux/perf_event.h Leo Yan
2020-07-15 5:17 ` [PATCH v2 0/6] arm64: perf: Proper cap_user_time* support Ahmed S. Darwish
2020-07-15 6:29 ` Leo Yan
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