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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: Mark 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: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210525140232.53872-10-mark.rutland@arm.com
This commit is contained in:
Mark Rutland 2021-05-25 15:02:08 +01:00 committed by Peter Zijlstra
parent d0e03218ca
commit f8b6455a9d
1 changed files with 62 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

71
include/asm-generic/atomic.h
View File

@ -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 */