csky: smp_mb__after_spinlock

From: peterz
Date: Wed Aug 05 2020 - 15:52:12 EST


Hi,

While doing an audit of smp_mb__after_spinlock, I found that csky
defines it, why?

CSKY only has smp_mb(), it doesn't override __atomic_acquire_fence or
otherwise special cases it's atomic*_acquire() primitives. It has an
explicit smp_mb() in its arch_spin_lock().

---
diff --git a/arch/csky/include/asm/spinlock.h b/arch/csky/include/asm/spinlock.h
index 7cf3f2b34cea..22a05caf2d18 100644
--- a/arch/csky/include/asm/spinlock.h
+++ b/arch/csky/include/asm/spinlock.h
@@ -88,9 +88,6 @@ static inline int arch_spin_is_contended(arch_spinlock_t *lock)

#include <asm/qrwlock.h>

-/* See include/linux/spinlock.h */
-#define smp_mb__after_spinlock() smp_mb()
-
#else /* CONFIG_QUEUED_RWLOCKS */

/*