| Message ID | 1407389778-6793-2-git-send-email-mpe@ellerman.id.au (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 78e05b1421fa41ae8457701140933baa5e7d9479 |
| Headers | show |
diff --git a/arch/powerpc/lib/locks.c b/arch/powerpc/lib/locks.c index 0c9c8d7d0734..170a0346f756 100644 --- a/arch/powerpc/lib/locks.c +++ b/arch/powerpc/lib/locks.c @@ -70,12 +70,16 @@ void __rw_yield(arch_rwlock_t *rw) void arch_spin_unlock_wait(arch_spinlock_t *lock) { + smp_mb(); + while (lock->slock) { HMT_low(); if (SHARED_PROCESSOR) __spin_yield(lock); } HMT_medium(); + + smp_mb(); } EXPORT_SYMBOL(arch_spin_unlock_wait);
Similar to the previous commit which described why we need to add a barrier to arch_spin_is_locked(), we have a similar problem with spin_unlock_wait(). We need a barrier on entry to ensure any spinlock we have previously taken is visibly locked prior to the load of lock->slock. It's also not clear if spin_unlock_wait() is intended to have ACQUIRE semantics. For now be conservative and add a barrier on exit to give it ACQUIRE semantics. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> --- arch/powerpc/lib/locks.c | 4 ++++ 1 file changed, 4 insertions(+)