asm-generic: guard smp_store_release/load_acquire

Allow architectures to override smp_store_release
and smp_load_acquire by guarding the defines
in asm-generic/barrier.h with ifndef directives.

This is in preparation to reusing asm-generic/barrier.h
on architectures which have their own definition
of these macros.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index 0f45f93..987b2e0 100644 (file)
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -104,13 +104,16 @@
 #define smp_mb__after_atomic() smp_mb()
 #endif
 
+#ifndef smp_store_release
 #define smp_store_release(p, v)                                                \
 do {                                                                   \
        compiletime_assert_atomic_type(*p);                             \
        smp_mb();                                                       \
        WRITE_ONCE(*p, v);                                              \
 } while (0)
+#endif
 
+#ifndef smp_load_acquire
 #define smp_load_acquire(p)                                            \
 ({                                                                     \
        typeof(*p) ___p1 = READ_ONCE(*p);                               \
@@ -118,6 +121,7 @@ do {                                                                        \
        smp_mb();                                                       \
        ___p1;                                                          \
 })
+#endif
 
 #endif /* !__ASSEMBLY__ */
 #endif /* __ASM_GENERIC_BARRIER_H */