Merge tag 'dm-4.2-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device...

[firefly-linux-kernel-4.4.55.git] / arch / tile / lib / spinlock_32.c

diff --git a/arch/tile/lib/spinlock_32.c b/arch/tile/lib/spinlock_32.c
index b34f79aada48efca7a1b350894f0dd7f4b98a7f4..88c2a53362e738110913134b840e1abe01df9fd9 100644 (file)
--- a/arch/tile/lib/spinlock_32.c
+++ b/arch/tile/lib/spinlock_32.c
@@ -65,8 +65,17 @@ EXPORT_SYMBOL(arch_spin_trylock);
 void arch_spin_unlock_wait(arch_spinlock_t *lock)
 {
        u32 iterations = 0;
-       while (arch_spin_is_locked(lock))
+       int curr = READ_ONCE(lock->current_ticket);
+       int next = READ_ONCE(lock->next_ticket);
+
+       /* Return immediately if unlocked. */
+       if (next == curr)
+               return;
+
+       /* Wait until the current locker has released the lock. */
+       do {
                delay_backoff(iterations++);
+       } while (READ_ONCE(lock->current_ticket) == curr);
 }
 EXPORT_SYMBOL(arch_spin_unlock_wait);