Merge branch 'for-4.8/core' of git://git.kernel.dk/linux-block

[karo-tx-linux.git] / arch / arm / include / asm / spinlock.h

diff --git a/arch/arm/include/asm/spinlock.h b/arch/arm/include/asm/spinlock.h
index 0fa418463f49e95696c6d6b7ea9ac8d3d2798647..4bec4544207243d477b2e326b50119cc842526fe 100644 (file)
--- a/arch/arm/include/asm/spinlock.h
+++ b/arch/arm/include/asm/spinlock.h
@@ -6,6 +6,8 @@
 #endif
 
 #include <linux/prefetch.h>
+#include <asm/barrier.h>
+#include <asm/processor.h>
 
 /*
  * sev and wfe are ARMv6K extensions.  Uniprocessor ARMv6 may not have the K
@@ -50,8 +52,21 @@ static inline void dsb_sev(void)
  * memory.
  */
 
-#define arch_spin_unlock_wait(lock) \
-       do { while (arch_spin_is_locked(lock)) cpu_relax(); } while (0)
+static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
+{
+       u16 owner = READ_ONCE(lock->tickets.owner);
+
+       for (;;) {
+               arch_spinlock_t tmp = READ_ONCE(*lock);
+
+               if (tmp.tickets.owner == tmp.tickets.next ||
+                   tmp.tickets.owner != owner)
+                       break;
+
+               wfe();
+       }
+       smp_acquire__after_ctrl_dep();
+}
 
 #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)