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

["Michael S. Tsirkin" <mst@xxxxxxxxxx>]

From: Davidlohr Bueso <dave@xxxxxxxxxxxx>

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@xxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: <linux-arch@xxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: dave@xxxxxxxxxxxx
Link: 
http://lkml.kernel.org/r/1445975631-17047-3-git-send-email-dave@xxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 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


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel