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    Subject[PATCH 2/8] powerpc/pseries: use smp_rmb() in H_CONFER spin yield
    Date
    There is no need for rmb(), this allows faster lwsync here.

    Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
    ---
    arch/powerpc/lib/locks.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff --git a/arch/powerpc/lib/locks.c b/arch/powerpc/lib/locks.c
    index 6440d5943c00..47a530de733e 100644
    --- a/arch/powerpc/lib/locks.c
    +++ b/arch/powerpc/lib/locks.c
    @@ -30,7 +30,7 @@ void splpar_spin_yield(arch_spinlock_t *lock)
    yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count);
    if ((yield_count & 1) == 0)
    return; /* virtual cpu is currently running */
    - rmb();
    + smp_rmb();
    if (lock->slock != lock_value)
    return; /* something has changed */
    plpar_hcall_norets(H_CONFER,
    @@ -56,7 +56,7 @@ void splpar_rw_yield(arch_rwlock_t *rw)
    yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count);
    if ((yield_count & 1) == 0)
    return; /* virtual cpu is currently running */
    - rmb();
    + smp_rmb();
    if (rw->lock != lock_value)
    return; /* something has changed */
    plpar_hcall_norets(H_CONFER,
    --
    2.23.0
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