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Commit febdbfe8 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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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: default avatarPeter Zijlstra <peterz@infradead.org>
Acked-by: default avatarPaul 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: default avatarIngo Molnar <mingo@kernel.org>
parent 2ab08ee9

include/asm-generic/atomic.h

+1 −6
Original line number Original line Diff line number Diff line
@@ -16,6 +16,7 @@ 
#define __ASM_GENERIC_ATOMIC_H

#define __ASM_GENERIC_ATOMIC_H





#include <asm/cmpxchg.h>

#include <asm/cmpxchg.h>

#include <asm/barrier.h>





#ifdef CONFIG_SMP

#ifdef CONFIG_SMP

/* Force people to define core atomics */

/* Force people to define core atomics */
@@ -182,11 +183,5 @@ static inline void atomic_set_mask(unsigned int mask, atomic_t *v) 
}

}

#endif

#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 /* __KERNEL__ */

#endif /* __ASM_GENERIC_ATOMIC_H */
 
#endif /* __ASM_GENERIC_ATOMIC_H */

include/asm-generic/barrier.h

+8 −0
Original line number Original line Diff line number Diff line
@@ -62,6 +62,14 @@ 
#define set_mb(var, value)  do { (var) = (value); mb(); } while (0)

#define set_mb(var, value)  do { (var) = (value); mb(); } while (0)

#endif

#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)						\

#define smp_store_release(p, v)						\

do {									\

do {									\

	compiletime_assert_atomic_type(*p);				\

	compiletime_assert_atomic_type(*p);				\

include/asm-generic/bitops.h

+1 −8
Original line number Original line Diff line number Diff line
@@ -11,14 +11,7 @@ 




#include <linux/irqflags.h>

#include <linux/irqflags.h>

#include <linux/compiler.h>

#include <linux/compiler.h>



#include <asm/barrier.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-generic/bitops/__ffs.h>

#include <asm-generic/bitops/__ffs.h>

#include <asm-generic/bitops/ffz.h>

#include <asm-generic/bitops/ffz.h>

include/linux/atomic.h

+36 −0
Original line number Original line Diff line number Diff line
@@ -3,6 +3,42 @@ 
#define _LINUX_ATOMIC_H

#define _LINUX_ATOMIC_H

#include <asm/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

 * atomic_add_unless - add unless the number is already a given value

 * @v: pointer of type atomic_t

 * @v: pointer of type atomic_t

include/linux/bitops.h

+20 −0
Original line number Original line Diff line number Diff line
@@ -32,6 +32,26 @@ extern unsigned long __sw_hweight64(__u64 w); 
 */

 */

#include <asm/bitops.h>

#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) \

#define for_each_set_bit(bit, addr, size) \

	for ((bit) = find_first_bit((addr), (size));		\

	for ((bit) = find_first_bit((addr), (size));		\

	     (bit) < (size);					\

	     (bit) < (size);					\