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authorPeter Zijlstra <peterz@infradead.org>2014-02-06 18:16:07 +0100
committerIngo Molnar <mingo@kernel.org>2014-04-18 11:40:30 +0200
commitfebdbfe8a91ce0d11939d4940b592eb0dba8d663 (patch)
tree5651dc5030d3cc43a0e852f60ca2627835ef194f /include
parent2ab08ee9f0a4eba27c7c4ce0b6d5118e8a18554b (diff)
arch: Prepare for smp_mb__{before,after}_atomic()
Since the smp_mb__{before,after}*() ops are fundamentally dependent on how an arch can implement atomics it doesn't make sense to have 3 variants of them. They must all be the same. Furthermore, the 3 variants suggest they're only valid for those 3 atomic ops, while we have many more where they could be applied. So move away from smp_mb__{before,after}_{atomic,clear}_{dec,inc,bit}() and reduce the interface to just the two: smp_mb__{before,after}_atomic(). This patch prepares the way by introducing default implementations in asm-generic/barrier.h that default to a full barrier and providing __deprecated inlines for the previous 6 barriers if they're not provided by the arch. This should allow for a mostly painless transition (lots of deprecated warns in the interim). Signed-off-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Link: http://lkml.kernel.org/n/tip-wr59327qdyi9mbzn6x937s4e@git.kernel.org Cc: Arnd Bergmann <arnd@arndb.de> Cc: "Chen, Gong" <gong.chen@linux.intel.com> Cc: John Sullivan <jsrhbz@kanargh.force9.co.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mauro Carvalho Chehab <m.chehab@samsung.com> Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include')
-rw-r--r--include/asm-generic/atomic.h7
-rw-r--r--include/asm-generic/barrier.h8
-rw-r--r--include/asm-generic/bitops.h9
-rw-r--r--include/linux/atomic.h36
-rw-r--r--include/linux/bitops.h20
5 files changed, 66 insertions, 14 deletions
diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h
index 33bd2de3bc1e..9c79e7603459 100644
--- a/include/asm-generic/atomic.h
+++ b/include/asm-generic/atomic.h
@@ -16,6 +16,7 @@
#define __ASM_GENERIC_ATOMIC_H
#include <asm/cmpxchg.h>
+#include <asm/barrier.h>
#ifdef CONFIG_SMP
/* Force people to define core atomics */
@@ -182,11 +183,5 @@ static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
}
#endif
-/* Assume that atomic operations are already serializing */
-#define smp_mb__before_atomic_dec() barrier()
-#define smp_mb__after_atomic_dec() barrier()
-#define smp_mb__before_atomic_inc() barrier()
-#define smp_mb__after_atomic_inc() barrier()
-
#endif /* __KERNEL__ */
#endif /* __ASM_GENERIC_ATOMIC_H */
diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index 6f692f8ac664..1402fa855388 100644
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -62,6 +62,14 @@
#define set_mb(var, value) do { (var) = (value); mb(); } while (0)
#endif
+#ifndef smp_mb__before_atomic
+#define smp_mb__before_atomic() smp_mb()
+#endif
+
+#ifndef smp_mb__after_atomic
+#define smp_mb__after_atomic() smp_mb()
+#endif
+
#define smp_store_release(p, v) \
do { \
compiletime_assert_atomic_type(*p); \
diff --git a/include/asm-generic/bitops.h b/include/asm-generic/bitops.h
index 280ca7a96f75..dcdcacf2fd2b 100644
--- a/include/asm-generic/bitops.h
+++ b/include/asm-generic/bitops.h
@@ -11,14 +11,7 @@
#include <linux/irqflags.h>
#include <linux/compiler.h>
-
-/*
- * clear_bit may not imply a memory barrier
- */
-#ifndef smp_mb__before_clear_bit
-#define smp_mb__before_clear_bit() smp_mb()
-#define smp_mb__after_clear_bit() smp_mb()
-#endif
+#include <asm/barrier.h>
#include <asm-generic/bitops/__ffs.h>
#include <asm-generic/bitops/ffz.h>
diff --git a/include/linux/atomic.h b/include/linux/atomic.h
index 5b08a8540ecf..fef3a809e7cf 100644
--- a/include/linux/atomic.h
+++ b/include/linux/atomic.h
@@ -3,6 +3,42 @@
#define _LINUX_ATOMIC_H
#include <asm/atomic.h>
+/*
+ * Provide __deprecated wrappers for the new interface, avoid flag day changes.
+ * We need the ugly external functions to break header recursion hell.
+ */
+#ifndef smp_mb__before_atomic_inc
+static inline void __deprecated smp_mb__before_atomic_inc(void)
+{
+ extern void __smp_mb__before_atomic(void);
+ __smp_mb__before_atomic();
+}
+#endif
+
+#ifndef smp_mb__after_atomic_inc
+static inline void __deprecated smp_mb__after_atomic_inc(void)
+{
+ extern void __smp_mb__after_atomic(void);
+ __smp_mb__after_atomic();
+}
+#endif
+
+#ifndef smp_mb__before_atomic_dec
+static inline void __deprecated smp_mb__before_atomic_dec(void)
+{
+ extern void __smp_mb__before_atomic(void);
+ __smp_mb__before_atomic();
+}
+#endif
+
+#ifndef smp_mb__after_atomic_dec
+static inline void __deprecated smp_mb__after_atomic_dec(void)
+{
+ extern void __smp_mb__after_atomic(void);
+ __smp_mb__after_atomic();
+}
+#endif
+
/**
* atomic_add_unless - add unless the number is already a given value
* @v: pointer of type atomic_t
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index be5fd38bd5a0..cbc5833fb221 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -32,6 +32,26 @@ extern unsigned long __sw_hweight64(__u64 w);
*/
#include <asm/bitops.h>
+/*
+ * Provide __deprecated wrappers for the new interface, avoid flag day changes.
+ * We need the ugly external functions to break header recursion hell.
+ */
+#ifndef smp_mb__before_clear_bit
+static inline void __deprecated smp_mb__before_clear_bit(void)
+{
+ extern void __smp_mb__before_atomic(void);
+ __smp_mb__before_atomic();
+}
+#endif
+
+#ifndef smp_mb__after_clear_bit
+static inline void __deprecated smp_mb__after_clear_bit(void)
+{
+ extern void __smp_mb__after_atomic(void);
+ __smp_mb__after_atomic();
+}
+#endif
+
#define for_each_set_bit(bit, addr, size) \
for ((bit) = find_first_bit((addr), (size)); \
(bit) < (size); \