The following commit has been merged into the locking/core branch of tip: Commit-ID: d3b35b87f436c1b226a8061bee9c8875ba6658bd Gitweb: https://git.kernel.org/tip/d3b35b87f436c1b226a8061bee9c8875ba6658bd Author: Ahmed S. Darwish <a.darwish@xxxxxxxxxxxxx> AuthorDate: Mon, 20 Jul 2020 17:55:09 +02:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Wed, 29 Jul 2020 16:14:23 +02:00 seqlock: seqcount_t latch: End read sections with read_seqcount_retry() The seqcount_t latch reader example at the raw_write_seqcount_latch() kernel-doc comment ends the latch read section with a manual smp memory barrier and sequence counter comparison. This is technically correct, but it is suboptimal: read_seqcount_retry() already contains the same logic of an smp memory barrier and sequence counter comparison. End the latch read critical section example with read_seqcount_retry(). Signed-off-by: Ahmed S. Darwish <a.darwish@xxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20200720155530.1173732-4-a.darwish@xxxxxxxxxxxxx --- include/linux/seqlock.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index 6c4f68e..d724b5e 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -363,8 +363,8 @@ static inline int raw_read_seqcount_latch(seqcount_t *s) * idx = seq & 0x01; * entry = data_query(latch->data[idx], ...); * - * smp_rmb(); - * } while (seq != latch->seq); + * // read_seqcount_retry() includes needed smp_rmb() + * } while (read_seqcount_retry(&latch->seq, seq)); * * return entry; * }
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