[PATCH v2 01/32] lcoking/barriers, arch: Use smp barriers in smp_store_release()

Michael S. Tsirkin
2015-12-31T19:05:45Z

From: Davidlohr Bueso <dave at stgolabs.net>

With commit b92b8b35a2e ("locking/arch: Rename set_mb() to
smp_store_mb()")
it was made clear that the context of this call (and thus set_mb)
is strictly for CPU ordering, as opposed to IO. As such all archs
should use the smp variant of mb(), respecting the semantics and
saving a mandatory barrier on UP.

Signed-off-by: Davidlohr Bueso <dbueso at suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org>
Cc: <linux-arch at vger.kernel.org>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens at de.ibm.com>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Cc: Paul E. McKenney <paulmck at linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Tony Luck <tony.luck at intel.com>
Cc: dave at stgolabs.net
Link: http://lkml.kernel.org/r/1445975631-17047-3-git-send-email-dave at
stgolabs.net
Signed-off-by: Ingo Molnar <mingo at kernel.org>
---
 arch/ia64/include/asm/barrier.h    | 2 +-
 arch/powerpc/include/asm/barrier.h | 2 +-
 arch/s390/include/asm/barrier.h    | 2 +-
 include/asm-generic/barrier.h      | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/ia64/include/asm/barrier.h b/arch/ia64/include/asm/barrier.h
index df896a1..209c4b8 100644
--- a/arch/ia64/include/asm/barrier.h
+++ b/arch/ia64/include/asm/barrier.h
@@ -77,7 +77,7 @@ do {									\
 	___p1;								\
 })

-#define smp_store_mb(var, value)	do { WRITE_ONCE(var, value); mb(); } while (0)
+#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } while
(0)

 /*
  * The group barrier in front of the rsm & ssm are necessary to ensure
diff --git a/arch/powerpc/include/asm/barrier.h
b/arch/powerpc/include/asm/barrier.h
index 0eca6ef..a7af5fb 100644
--- a/arch/powerpc/include/asm/barrier.h
+++ b/arch/powerpc/include/asm/barrier.h
@@ -34,7 +34,7 @@
 #define rmb()  __asm__ __volatile__ ("sync" : : : "memory")
 #define wmb()  __asm__ __volatile__ ("sync" : : : "memory")

-#define smp_store_mb(var, value)	do { WRITE_ONCE(var, value); mb(); } while (0)
+#define smp_store_mb(var, value) do { WRITE_ONCE(var, value); smp_mb(); } while
(0)

 #ifdef __SUBARCH_HAS_LWSYNC
 #    define SMPWMB      LWSYNC
diff --git a/arch/s390/include/asm/barrier.h b/arch/s390/include/asm/barrier.h
index d68e11e..7ffd0b1 100644
--- a/arch/s390/include/asm/barrier.h
+++ b/arch/s390/include/asm/barrier.h
@@ -36,7 +36,7 @@
 #define smp_mb__before_atomic()		smp_mb()
 #define smp_mb__after_atomic()		smp_mb()

-#define smp_store_mb(var, value)		do { WRITE_ONCE(var, value); mb(); } while
(0)
+#define smp_store_mb(var, value)	do { WRITE_ONCE(var, value); smp_mb(); } while
(0)

 #define smp_store_release(p, v)						\
 do {									\
diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index b42afad..0f45f93 100644
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -93,7 +93,7 @@
 #endif	/* CONFIG_SMP */

 #ifndef smp_store_mb
-#define smp_store_mb(var, value)  do { WRITE_ONCE(var, value); mb(); } while
(0)
+#define smp_store_mb(var, value)  do { WRITE_ONCE(var, value); smp_mb(); }
while (0)
 #endif

 #ifndef smp_mb__before_atomic
--
MST