Commit f8b6455a authored by Mark Rutland's avatar Mark Rutland Committed by Peter Zijlstra
Browse files

locking/atomic: atomic: support ARCH_ATOMIC 



We'd like all architectures to convert to ARCH_ATOMIC, as this will
enable functionality, and once all architectures are converted it will
be possible to make significant cleanups to the atomic headers.

A number of architectures use asm-generic/atomic.h, and it's impractical
to convert the header and all these architectures in one go. To make it
possible to convert them one-by-one, let's make the asm-generic
implementation function as either atomic_*() or arch_atomic_*()
depending on whether ARCH_ATOMIC is selected. To do this, the C
implementations are prefixed as generic_atomic_*(), and preprocessor
definitions map atomic_*()/arch_atomic_*() onto these as
appropriate.

Once all users are moved over to ARCH_ATOMIC the ifdeffery in the header
can be simplified and/or removed entirely.

For existing users (none of which select ARCH_ATOMIC), there should be
no functional change as a result of this patch.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210525140232.53872-10-mark.rutland@arm.com
parent d0e03218

include/asm-generic/atomic.h

+62 −9
Original line number Diff line number Diff line
@@ -12,39 +12,47 @@ 
#include <asm/cmpxchg.h>

#include <asm/barrier.h>



#ifdef CONFIG_ARCH_ATOMIC

#define __ga_cmpxchg	arch_cmpxchg

#define __ga_xchg	arch_xchg

#else

#define __ga_cmpxchg	cmpxchg

#define __ga_xchg	xchg

#endif



#ifdef CONFIG_SMP



/* we can build all atomic primitives from cmpxchg */



#define ATOMIC_OP(op, c_op)						\

static inline void atomic_##op(int i, atomic_t *v)			\

static inline void generic_atomic_##op(int i, atomic_t *v)		\

{									\

	int c, old;							\

									\

	c = v->counter;							\

	while ((old = cmpxchg(&v->counter, c, c c_op i)) != c)		\

	while ((old = __ga_cmpxchg(&v->counter, c, c c_op i)) != c)	\

		c = old;						\

}



#define ATOMIC_OP_RETURN(op, c_op)					\

static inline int atomic_##op##_return(int i, atomic_t *v)		\

static inline int generic_atomic_##op##_return(int i, atomic_t *v)	\

{									\

	int c, old;							\

									\

	c = v->counter;							\

	while ((old = cmpxchg(&v->counter, c, c c_op i)) != c)		\

	while ((old = __ga_cmpxchg(&v->counter, c, c c_op i)) != c)	\

		c = old;						\

									\

	return c c_op i;						\

}



#define ATOMIC_FETCH_OP(op, c_op)					\

static inline int atomic_fetch_##op(int i, atomic_t *v)			\

static inline int generic_atomic_fetch_##op(int i, atomic_t *v)		\

{									\

	int c, old;							\

									\

	c = v->counter;							\

	while ((old = cmpxchg(&v->counter, c, c c_op i)) != c)		\

	while ((old = __ga_cmpxchg(&v->counter, c, c c_op i)) != c)	\

		c = old;						\

									\

	return c;							\
@@ -55,7 +63,7 @@ static inline int atomic_fetch_##op(int i, atomic_t *v) \ 
#include <linux/irqflags.h>



#define ATOMIC_OP(op, c_op)						\

static inline void atomic_##op(int i, atomic_t *v)			\

static inline void generic_atomic_##op(int i, atomic_t *v)		\

{									\

	unsigned long flags;						\

									\
@@ -65,7 +73,7 @@ static inline void atomic_##op(int i, atomic_t *v) \ 
}



#define ATOMIC_OP_RETURN(op, c_op)					\

static inline int atomic_##op##_return(int i, atomic_t *v)		\

static inline int generic_atomic_##op##_return(int i, atomic_t *v)	\

{									\

	unsigned long flags;						\

	int ret;							\
@@ -78,7 +86,7 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \ 
}



#define ATOMIC_FETCH_OP(op, c_op)					\

static inline int atomic_fetch_##op(int i, atomic_t *v)			\

static inline int generic_atomic_fetch_##op(int i, atomic_t *v)		\

{									\

	unsigned long flags;						\

	int ret;							\
@@ -112,10 +120,55 @@ ATOMIC_OP(xor, ^) 
#undef ATOMIC_OP_RETURN

#undef ATOMIC_OP



#undef __ga_cmpxchg

#undef __ga_xchg



#ifdef CONFIG_ARCH_ATOMIC



#define arch_atomic_add_return			generic_atomic_add_return

#define arch_atomic_sub_return			generic_atomic_sub_return



#define arch_atomic_fetch_add			generic_atomic_fetch_add

#define arch_atomic_fetch_sub			generic_atomic_fetch_sub

#define arch_atomic_fetch_and			generic_atomic_fetch_and

#define arch_atomic_fetch_or			generic_atomic_fetch_or

#define arch_atomic_fetch_xor			generic_atomic_fetch_xor



#define arch_atomic_add				generic_atomic_add

#define arch_atomic_sub				generic_atomic_sub

#define arch_atomic_and				generic_atomic_and

#define arch_atomic_or				generic_atomic_or

#define arch_atomic_xor				generic_atomic_xor



#define arch_atomic_read(v)			READ_ONCE((v)->counter)

#define arch_atomic_set(v, i)			WRITE_ONCE(((v)->counter), (i))



#define arch_atomic_xchg(ptr, v)		(arch_xchg(&(ptr)->counter, (v)))

#define arch_atomic_cmpxchg(v, old, new)	(arch_cmpxchg(&((v)->counter), (old), (new)))



#else /* CONFIG_ARCH_ATOMIC */



#define atomic_add_return		generic_atomic_add_return

#define atomic_sub_return		generic_atomic_sub_return



#define atomic_fetch_add		generic_atomic_fetch_add

#define atomic_fetch_sub		generic_atomic_fetch_sub

#define atomic_fetch_and		generic_atomic_fetch_and

#define atomic_fetch_or			generic_atomic_fetch_or

#define atomic_fetch_xor		generic_atomic_fetch_xor



#define atomic_add			generic_atomic_add

#define atomic_sub			generic_atomic_sub

#define atomic_and			generic_atomic_and

#define atomic_or			generic_atomic_or

#define atomic_xor			generic_atomic_xor



#define atomic_read(v)			READ_ONCE((v)->counter)

#define atomic_set(v, i)		WRITE_ONCE(((v)->counter), (i))



#define atomic_xchg(ptr, v)		(xchg(&(ptr)->counter, (v)))

#define atomic_cmpxchg(v, old, new)	(cmpxchg(&((v)->counter), (old), (new)))



#endif /* CONFIG_ARCH_ATOMIC */



#endif /* __ASM_GENERIC_ATOMIC_H */