Merge tag 'gpio-v4.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux...

[cascardo/linux.git] / arch / tile / lib / spinlock_32.c

diff --git a/arch/tile/lib/spinlock_32.c b/arch/tile/lib/spinlock_32.c
index b34f79a..076c6cc 100644 (file)
--- a/arch/tile/lib/spinlock_32.c
+++ b/arch/tile/lib/spinlock_32.c
@@ -65,8 +65,23 @@ 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);
+
+       /*
+        * The TILE architecture doesn't do read speculation; therefore
+        * a control dependency guarantees a LOAD->{LOAD,STORE} order.
+        */
+       barrier();
 }
 EXPORT_SYMBOL(arch_spin_unlock_wait);