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    Subject[PATCH 08/15] seqlock: provide the same ordering semantics as mainline
    Date
    From: Julia Cartwright <julia@ni.com>

    The mainline implementation of read_seqbegin() orders prior loads w.r.t.
    the read-side critical section. Fixup the RT writer-boosting
    implementation to provide the same guarantee.

    Also, while we're here, update the usage of ACCESS_ONCE() to use
    READ_ONCE().

    Fixes: e69f15cf77c23 ("seqlock: Prevent rt starvation")
    Cc: stable-rt@vger.kernel.org
    Signed-off-by: Julia Cartwright <julia@ni.com>
    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    (cherry picked from commit afa4c06b89a3c0fb7784ff900ccd707bef519cb7)
    Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
    ---
    include/linux/seqlock.h | 1 +
    1 file changed, 1 insertion(+)

    diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h
    index 4acd0e2fb5cb..efa234031230 100644
    --- a/include/linux/seqlock.h
    +++ b/include/linux/seqlock.h
    @@ -338,6 +338,7 @@ repeat:
    spin_unlock_wait(&sl->lock);
    goto repeat;
    }
    + smp_rmb();
    return ret;
    }
    #endif
    --
    2.14.1
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