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    Subject[PATCH v4 03/24] seqlock: seqcount_t latch: End read sections with read_seqcount_retry()
    Date
    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@linutronix.de>
    ---
    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 6c4f68ef1393..d724b5e5408d 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;
    * }
    --
    2.20.1
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