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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-09-27 10:34:19 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-09-27 10:34:19 -0300
commit1c29f4306f557ef5d9ed515ec8881f4d1735b058 (patch)
tree1359b9f8403af67e35bbbaae36e2b60c9bb3d2da /arch/arm64/include
parent5b465b045af3a649a89b8a5c5bfdece20ffc0345 (diff)
Linux-libre 4.7.5-gnupck-4.7.5-gnu
Diffstat (limited to 'arch/arm64/include')
-rw-r--r--arch/arm64/include/asm/spinlock.h10
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
index e875a5a55..89206b568 100644
--- a/arch/arm64/include/asm/spinlock.h
+++ b/arch/arm64/include/asm/spinlock.h
@@ -363,4 +363,14 @@ static inline int arch_read_trylock(arch_rwlock_t *rw)
#define arch_read_relax(lock) cpu_relax()
#define arch_write_relax(lock) cpu_relax()
+/*
+ * Accesses appearing in program order before a spin_lock() operation
+ * can be reordered with accesses inside the critical section, by virtue
+ * of arch_spin_lock being constructed using acquire semantics.
+ *
+ * In cases where this is problematic (e.g. try_to_wake_up), an
+ * smp_mb__before_spinlock() can restore the required ordering.
+ */
+#define smp_mb__before_spinlock() smp_mb()
+
#endif /* __ASM_SPINLOCK_H */