Re: [PATCH] atomic.h : standardizing atomic primitives

From: Mathieu Desnoyers
Date: Wed Jan 31 2007 - 11:26:04 EST

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Hi Peter,

Thanks for testing Andrew's fixes. I am wondering about what happened to
the Powerpc recursive include problems Andrew experienced. Quoting him :

"OK, I fixed eight separate compile errors in this patch series and
now powerpc is being very ugly with a twisty maze of include
dependencies.

I'm giving up. Someone should publish a suite of cross-compilers for us
so stuff like this doesn't need to happen."

I see that you have removed the include <asm/atomic.h> from bitops.h and
system.h in powerpc. If it compiles on every architectures, then it's a
good approach.

I planned to post a new patch which uses macros for cmpxchg and xchg in
asm-generic/atomic.h instead of inline functions. It would remove the
dependency on system.h. However, if your modifications work well on
every architecture, my fix might not be needed. Anyone has a preferred
solution ? I have not been able to setup my cross-compiler test bench
yet due to some hardware issues and waited for it before I released
further fixes, but if you want to try my macro-based fix, I could post
it.

And about the alpha build, Does the assembler errors also happen without
this patch ?

Regards,

Mathieu

* Peter Zijlstra (a.p.zijlstra@xxxxxxxxx) wrote:
>
> atomic.h : standardizing atomic primitives
>
> It mainly adds support for missing 64 bits cmpxchg and 64 bits atomic add
> unless. Therefore, principally 64 bits architectures are targeted by these
> patches. It also adds the complete list of atomic operations on the atomic_long
> type.
>
> build tested on:
>
> arm-pxa255-idp_defconfig-xbuild
> i386-defconfig-xbuild
> ia64-defconfig-xbuild
> mips-ip32_defconfig-xbuild
> mips-yosemite_defconfig-xbuild
> parisc-a500_defconfig-xbuild -- needs parisc-2.6 tree
> powerpc-ppc64_defconfig-xbuild
> sparc64-defconfig-xbuild
> sparc-defconfig-xbuild
> um-x86_64-defconfig-xbuild
> x86_64-defconfig-xbuild
>
> notable exception: alpha (assembler errors, guess binutils funkyness)
>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>
> ---
> include/asm-alpha/atomic.h | 51 ++++++++++++
> include/asm-generic/atomic.h | 169 +++++++++++++++++++++++++++++++++++++++++++
> include/asm-i386/atomic.h | 7 +
> include/asm-ia64/atomic.h | 25 +++++-
> include/asm-mips/atomic.h | 28 ++++++-
> include/asm-parisc/atomic.h | 29 ++++++-
> include/asm-powerpc/atomic.h | 40 +++++++++-
> include/asm-powerpc/bitops.h | 1
> include/asm-powerpc/system.h | 1
> include/asm-sparc64/atomic.h | 25 +++++-
> include/asm-x86_64/atomic.h | 38 ++++++++-
> 11 files changed, 392 insertions(+), 22 deletions(-)
>
> Index: linux-2.6/include/asm-alpha/atomic.h
> ===================================================================
> --- linux-2.6.orig/include/asm-alpha/atomic.h
> +++ linux-2.6/include/asm-alpha/atomic.h
> @@ -175,19 +175,64 @@ static __inline__ long atomic64_sub_retu
> return result;
> }
>
> -#define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
> +#define atomic64_cmpxchg(v, old, new) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), old, new))
> +#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
> +
> +#define atomic_cmpxchg(v, old, new) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), old, new))
> #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
>
> +/**
> + * atomic_add_unless - add unless the number is a given value
> + * @v: pointer of type atomic_t
> + * @a: the amount to add to v...
> + * @u: ...unless v is equal to u.
> + *
> + * Atomically adds @a to @v, so long as it was not @u.
> + * Returns non-zero if @v was not @u, and zero otherwise.
> + */
> #define atomic_add_unless(v, a, u) \
> ({ \
> - int c, old; \
> + __typeof__((v)->counter) c, old; \
> c = atomic_read(v); \
> - while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
> + for (;;) { \
> + if (unlikely(c == (u))) \
> + break; \
> + old = atomic_cmpxchg((v), c, c + (a)); \
> + if (likely(old == c)) \
> + break; \
> c = old; \
> + } \
> c != (u); \
> })
> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
>
> +/**
> + * atomic64_add_unless - add unless the number is a given value
> + * @v: pointer of type atomic64_t
> + * @a: the amount to add to v...
> + * @u: ...unless v is equal to u.
> + *
> + * Atomically adds @a to @v, so long as it was not @u.
> + * Returns non-zero if @v was not @u, and zero otherwise.
> + */
> +#define atomic64_add_unless(v, a, u) \
> +({ \
> + __typeof__((v)->counter) c, old; \
> + c = atomic64_read(v); \
> + for (;;) { \
> + if (unlikely(c == (u))) \
> + break; \
> + old = atomic64_cmpxchg((v), c, c + (a)); \
> + if (likely(old == c)) \
> + break; \
> + c = old; \
> + } \
> + c != (u); \
> +})
> +#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
> +
> #define atomic_add_negative(a, v) (atomic_add_return((a), (v)) < 0)
> #define atomic64_add_negative(a, v) (atomic64_add_return((a), (v)) < 0)
>
> Index: linux-2.6/include/asm-generic/atomic.h
> ===================================================================
> --- linux-2.6.orig/include/asm-generic/atomic.h
> +++ linux-2.6/include/asm-generic/atomic.h
> @@ -8,6 +8,7 @@
> * edit all arch specific atomic.h files.
> */
>
> +#include <asm/system.h>
> #include <asm/types.h>
>
> /*
> @@ -66,6 +67,90 @@ static inline void atomic_long_sub(long
> atomic64_sub(i, v);
> }
>
> +static inline int atomic_long_sub_and_test(long i, atomic_long_t *l)
> +{
> + atomic64_t *v = (atomic64_t *)l;
> +
> + return atomic64_sub_and_test(i, v);
> +}
> +
> +static inline int atomic_long_dec_and_test(atomic_long_t *l)
> +{
> + atomic64_t *v = (atomic64_t *)l;
> +
> + return atomic64_dec_and_test(v);
> +}
> +
> +static inline int atomic_long_inc_and_test(atomic_long_t *l)
> +{
> + atomic64_t *v = (atomic64_t *)l;
> +
> + return atomic64_inc_and_test(v);
> +}
> +
> +static inline int atomic_long_add_negative(long i, atomic_long_t *l)
> +{
> + atomic64_t *v = (atomic64_t *)l;
> +
> + return atomic64_add_negative(i, v);
> +}
> +
> +static inline long atomic_long_add_return(long i, atomic_long_t *l)
> +{
> + atomic64_t *v = (atomic64_t *)l;
> +
> + return (long)atomic64_add_return(i, v);
> +}
> +
> +static inline long atomic_long_sub_return(long i, atomic_long_t *l)
> +{
> + atomic64_t *v = (atomic64_t *)l;
> +
> + return (long)atomic64_sub_return(i, v);
> +}
> +
> +static inline long atomic_long_inc_return(atomic_long_t *l)
> +{
> + atomic64_t *v = (atomic64_t *)l;
> +
> + return (long)atomic64_inc_return(v);
> +}
> +
> +static inline long atomic_long_dec_return(atomic_long_t *l)
> +{
> + atomic64_t *v = (atomic64_t *)l;
> +
> + return (long)atomic64_dec_return(v);
> +}
> +
> +static inline long atomic_long_add_unless(atomic_long_t *l, long a, long u)
> +{
> + atomic64_t *v = (atomic64_t *)l;
> +
> + return (long)atomic64_add_unless(v, a, u);
> +}
> +
> +static inline long atomic_long_inc_not_zero(atomic_long_t *l)
> +{
> + atomic64_t *v = (atomic64_t *)l;
> +
> + return (long)atomic64_inc_not_zero(v);
> +}
> +
> +static inline long atomic_long_cmpxchg(atomic_long_t *l, long old, long new)
> +{
> + atomic64_t *v = (atomic64_t *)l;
> +
> + return (long)atomic64_cmpxchg(v, old, new);
> +}
> +
> +static inline long atomic_long_xchg(atomic_long_t *l, long new)
> +{
> + atomic64_t *v = (atomic64_t *)l;
> +
> + return (long)atomic64_xchg(v, new);
> +}
> +
> #else /* BITS_PER_LONG == 64 */
>
> typedef atomic_t atomic_long_t;
> @@ -113,6 +198,90 @@ static inline void atomic_long_sub(long
> atomic_sub(i, v);
> }
>
> +static inline int atomic_long_sub_and_test(long i, atomic_long_t *l)
> +{
> + atomic_t *v = (atomic_t *)l;
> +
> + return atomic_sub_and_test(i, v);
> +}
> +
> +static inline int atomic_long_dec_and_test(atomic_long_t *l)
> +{
> + atomic_t *v = (atomic_t *)l;
> +
> + return atomic_dec_and_test(v);
> +}
> +
> +static inline int atomic_long_inc_and_test(atomic_long_t *l)
> +{
> + atomic_t *v = (atomic_t *)l;
> +
> + return atomic_inc_and_test(v);
> +}
> +
> +static inline int atomic_long_add_negative(long i, atomic_long_t *l)
> +{
> + atomic_t *v = (atomic_t *)l;
> +
> + return atomic_add_negative(i, v);
> +}
> +
> +static inline long atomic_long_add_return(long i, atomic_long_t *l)
> +{
> + atomic_t *v = (atomic_t *)l;
> +
> + return (long)atomic_add_return(i, v);
> +}
> +
> +static inline long atomic_long_sub_return(long i, atomic_long_t *l)
> +{
> + atomic_t *v = (atomic_t *)l;
> +
> + return (long)atomic_sub_return(i, v);
> +}
> +
> +static inline long atomic_long_inc_return(atomic_long_t *l)
> +{
> + atomic_t *v = (atomic_t *)l;
> +
> + return (long)atomic_inc_return(v);
> +}
> +
> +static inline long atomic_long_dec_return(atomic_long_t *l)
> +{
> + atomic_t *v = (atomic_t *)l;
> +
> + return (long)atomic_dec_return(v);
> +}
> +
> +static inline long atomic_long_add_unless(atomic_long_t *l, long a, long u)
> +{
> + atomic_t *v = (atomic_t *)l;
> +
> + return (long)atomic_add_unless(v, a, u);
> +}
> +
> +static inline long atomic_long_inc_not_zero(atomic_long_t *l)
> +{
> + atomic_t *v = (atomic_t *)l;
> +
> + return (long)atomic_inc_not_zero(v);
> +}
> +
> +static inline long atomic_long_cmpxchg(atomic_long_t *l, long old, long new)
> +{
> + atomic_t *v = (atomic_t *)l;
> +
> + return (long)atomic_cmpxchg(v, old, new);
> +}
> +
> +static inline long atomic_long_xchg(atomic_long_t *l, long new)
> +{
> + atomic_t *v = (atomic_t *)l;
> +
> + return (long)atomic_xchg(v, new);
> +}
> +
> #endif /* BITS_PER_LONG == 64 */
>
> #endif /* _ASM_GENERIC_ATOMIC_H */
> Index: linux-2.6/include/asm-i386/atomic.h
> ===================================================================
> --- linux-2.6.orig/include/asm-i386/atomic.h
> +++ linux-2.6/include/asm-i386/atomic.h
> @@ -207,8 +207,9 @@ static __inline__ int atomic_sub_return(
> return atomic_add_return(-i,v);
> }
>
> -#define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
> -#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
> +#define atomic_cmpxchg(v, old, new) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), (old), (new)))
> +#define atomic_xchg(v, new) (xchg(&((v)->counter), (new)))
>
> /**
> * atomic_add_unless - add unless the number is a given value
> @@ -221,7 +222,7 @@ static __inline__ int atomic_sub_return(
> */
> #define atomic_add_unless(v, a, u) \
> ({ \
> - int c, old; \
> + __typeof__((v)->counter) c, old; \
> c = atomic_read(v); \
> for (;;) { \
> if (unlikely(c == (u))) \
> Index: linux-2.6/include/asm-ia64/atomic.h
> ===================================================================
> --- linux-2.6.orig/include/asm-ia64/atomic.h
> +++ linux-2.6/include/asm-ia64/atomic.h
> @@ -88,12 +88,17 @@ ia64_atomic64_sub (__s64 i, atomic64_t *
> return new;
> }
>
> -#define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
> +#define atomic_cmpxchg(v, old, new) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), old, new))
> #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
>
> +#define atomic64_cmpxchg(v, old, new) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), old, new))
> +#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
> +
> #define atomic_add_unless(v, a, u) \
> ({ \
> - int c, old; \
> + __typeof__(v->counter) c, old; \
> c = atomic_read(v); \
> for (;;) { \
> if (unlikely(c == (u))) \
> @@ -107,6 +112,22 @@ ia64_atomic64_sub (__s64 i, atomic64_t *
> })
> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
>
> +#define atomic64_add_unless(v, a, u) \
> +({ \
> + __typeof__(v->counter) c, old; \
> + c = atomic64_read(v); \
> + for (;;) { \
> + if (unlikely(c == (u))) \
> + break; \
> + old = atomic64_cmpxchg((v), c, c + (a)); \
> + if (likely(old == c)) \
> + break; \
> + c = old; \
> + } \
> + c != (u); \
> +})
> +#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
> +
> #define atomic_add_return(i,v) \
> ({ \
> int __ia64_aar_i = (i); \
> Index: linux-2.6/include/asm-mips/atomic.h
> ===================================================================
> --- linux-2.6.orig/include/asm-mips/atomic.h
> +++ linux-2.6/include/asm-mips/atomic.h
> @@ -291,8 +291,8 @@ static __inline__ int atomic_sub_if_posi
> return result;
> }
>
> -#define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
> -#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
> +#define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
> +#define atomic_xchg(v, new) (xchg(&((v)->counter), (new)))
>
> /**
> * atomic_add_unless - add unless the number is a given value
> @@ -305,7 +305,7 @@ static __inline__ int atomic_sub_if_posi
> */
> #define atomic_add_unless(v, a, u) \
> ({ \
> - int c, old; \
> + __typeof__((v)->counter) c, old; \
> c = atomic_read(v); \
> while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
> c = old; \
> @@ -651,6 +651,28 @@ static __inline__ long atomic64_sub_if_p
> return result;
> }
>
> +#define atomic64_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
> +#define atomic64_xchg(v, new) (xchg(&((v)->counter), (new)))
> +
> +/**
> + * atomic64_add_unless - add unless the number is a given value
> + * @v: pointer of type atomic64_t
> + * @a: the amount to add to v...
> + * @u: ...unless v is equal to u.
> + *
> + * Atomically adds @a to @v, so long as it was not @u.
> + * Returns non-zero if @v was not @u, and zero otherwise.
> + */
> +#define atomic64_add_unless(v, a, u) \
> +({ \
> + __typeof__((v)->counter) c, old; \
> + c = atomic_read(v); \
> + while (c != (u) && (old = atomic64_cmpxchg((v), c, c + (a))) != c) \
> + c = old; \
> + c != (u); \
> +})
> +#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
> +
> #define atomic64_dec_return(v) atomic64_sub_return(1,(v))
> #define atomic64_inc_return(v) atomic64_add_return(1,(v))
>
> Index: linux-2.6/include/asm-parisc/atomic.h
> ===================================================================
> --- linux-2.6.orig/include/asm-parisc/atomic.h
> +++ linux-2.6/include/asm-parisc/atomic.h
> @@ -163,7 +163,8 @@ static __inline__ int atomic_read(const
> }
>
> /* exported interface */
> -#define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
> +#define atomic_cmpxchg(v, o, n) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), (o), (n)))
> #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
>
> /**
> @@ -177,7 +178,7 @@ static __inline__ int atomic_read(const
> */
> #define atomic_add_unless(v, a, u) \
> ({ \
> - int c, old; \
> + __typeof__((v)->counter) c, old; \
> c = atomic_read(v); \
> while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
> c = old; \
> @@ -270,6 +271,30 @@ atomic64_read(const atomic64_t *v)
> #define atomic64_dec_and_test(v) (atomic64_dec_return(v) == 0)
> #define atomic64_sub_and_test(i,v) (atomic64_sub_return((i),(v)) == 0)
>
> +/* exported interface */
> +#define atomic64_cmpxchg(v, o, n) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), (o), (n)))
> +#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
> +
> +/**
> + * atomic64_add_unless - add unless the number is a given value
> + * @v: pointer of type atomic64_t
> + * @a: the amount to add to v...
> + * @u: ...unless v is equal to u.
> + *
> + * Atomically adds @a to @v, so long as it was not @u.
> + * Returns non-zero if @v was not @u, and zero otherwise.
> + */
> +#define atomic64_add_unless(v, a, u) \
> +({ \
> + __typeof__((v)->counter) c, old; \
> + c = atomic64_read(v); \
> + while (c != (u) && (old = atomic64_cmpxchg((v), c, c + (a))) != c) \
> + c = old; \
> + c != (u); \
> +})
> +#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
> +
> #endif /* CONFIG_64BIT */
>
> #include <asm-generic/atomic.h>
> Index: linux-2.6/include/asm-powerpc/atomic.h
> ===================================================================
> --- linux-2.6.orig/include/asm-powerpc/atomic.h
> +++ linux-2.6/include/asm-powerpc/atomic.h
> @@ -165,7 +165,8 @@ static __inline__ int atomic_dec_return(
> return t;
> }
>
> -#define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
> +#define atomic_cmpxchg(v, o, n) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), (o), (n)))
> #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
>
> /**
> @@ -413,6 +414,43 @@ static __inline__ long atomic64_dec_if_p
> return t;
> }
>
> +#define atomic64_cmpxchg(v, o, n) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), (o), (n)))
> +#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
> +
> +/**
> + * atomic64_add_unless - add unless the number is a given value
> + * @v: pointer of type atomic64_t
> + * @a: the amount to add to v...
> + * @u: ...unless v is equal to u.
> + *
> + * Atomically adds @a to @v, so long as it was not @u.
> + * Returns non-zero if @v was not @u, and zero otherwise.
> + */
> +static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u)
> +{
> + long t;
> +
> + __asm__ __volatile__ (
> + LWSYNC_ON_SMP
> +"1: ldarx %0,0,%1 # atomic_add_unless\n\
> + cmpd 0,%0,%3 \n\
> + beq- 2f \n\
> + add %0,%2,%0 \n"
> +" stdcx. %0,0,%1 \n\
> + bne- 1b \n"
> + ISYNC_ON_SMP
> +" subf %0,%2,%0 \n\
> +2:"
> + : "=&r" (t)
> + : "r" (&v->counter), "r" (a), "r" (u)
> + : "cc", "memory");
> +
> + return t != u;
> +}
> +
> +#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
> +
> #endif /* __powerpc64__ */
>
> #include <asm-generic/atomic.h>
> Index: linux-2.6/include/asm-powerpc/bitops.h
> ===================================================================
> --- linux-2.6.orig/include/asm-powerpc/bitops.h
> +++ linux-2.6/include/asm-powerpc/bitops.h
> @@ -39,7 +39,6 @@
> #ifdef __KERNEL__
>
> #include <linux/compiler.h>
> -#include <asm/atomic.h>
> #include <asm/asm-compat.h>
> #include <asm/synch.h>
>
> Index: linux-2.6/include/asm-powerpc/system.h
> ===================================================================
> --- linux-2.6.orig/include/asm-powerpc/system.h
> +++ linux-2.6/include/asm-powerpc/system.h
> @@ -7,7 +7,6 @@
> #include <linux/kernel.h>
>
> #include <asm/hw_irq.h>
> -#include <asm/atomic.h>
>
> /*
> * Memory barrier.
> Index: linux-2.6/include/asm-sparc64/atomic.h
> ===================================================================
> --- linux-2.6.orig/include/asm-sparc64/atomic.h
> +++ linux-2.6/include/asm-sparc64/atomic.h
> @@ -70,12 +70,13 @@ extern int atomic64_sub_ret(int, atomic6
> #define atomic_add_negative(i, v) (atomic_add_ret(i, v) < 0)
> #define atomic64_add_negative(i, v) (atomic64_add_ret(i, v) < 0)
>
> -#define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
> +#define atomic_cmpxchg(v, o, n) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), (o), (n)))
> #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
>
> #define atomic_add_unless(v, a, u) \
> ({ \
> - int c, old; \
> + __typeof__((v)->counter) c, old; \
> c = atomic_read(v); \
> for (;;) { \
> if (unlikely(c == (u))) \
> @@ -89,6 +90,26 @@ extern int atomic64_sub_ret(int, atomic6
> })
> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
>
> +#define atomic64_cmpxchg(v, o, n) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), (o), (n)))
> +#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
> +
> +#define atomic64_add_unless(v, a, u) \
> +({ \
> + __typeof__((v)->counter) c, old; \
> + c = atomic64_read(v); \
> + for (;;) { \
> + if (unlikely(c == (u))) \
> + break; \
> + old = atomic64_cmpxchg((v), c, c + (a)); \
> + if (likely(old == c)) \
> + break; \
> + c = old; \
> + } \
> + likely(c != (u)); \
> +})
> +#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
> +
> /* Atomic operations are already serializing */
> #ifdef CONFIG_SMP
> #define smp_mb__before_atomic_dec() membar_storeload_loadload();
> Index: linux-2.6/include/asm-x86_64/atomic.h
> ===================================================================
> --- linux-2.6.orig/include/asm-x86_64/atomic.h
> +++ linux-2.6/include/asm-x86_64/atomic.h
> @@ -375,8 +375,8 @@ static __inline__ long atomic64_add_retu
> long __i = i;
> __asm__ __volatile__(
> LOCK_PREFIX "xaddq %0, %1;"
> - :"=r"(i)
> - :"m"(v->counter), "0"(i));
> + :"+r" (i), "+m" (v->counter)
> + : : "memory");
> return i + __i;
> }
>
> @@ -388,7 +388,12 @@ static __inline__ long atomic64_sub_retu
> #define atomic64_inc_return(v) (atomic64_add_return(1,v))
> #define atomic64_dec_return(v) (atomic64_sub_return(1,v))
>
> -#define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
> +#define atomic64_cmpxchg(v, old, new) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), old, new))
> +#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
> +
> +#define atomic_cmpxchg(v, old, new) \
> + ((__typeof__((v)->counter))cmpxchg(&((v)->counter), old, new))
> #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
>
> /**
> @@ -402,7 +407,7 @@ static __inline__ long atomic64_sub_retu
> */
> #define atomic_add_unless(v, a, u) \
> ({ \
> - int c, old; \
> + __typeof__((v)->counter) c, old; \
> c = atomic_read(v); \
> for (;;) { \
> if (unlikely(c == (u))) \
> @@ -416,6 +421,31 @@ static __inline__ long atomic64_sub_retu
> })
> #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
>
> +/**
> + * atomic64_add_unless - add unless the number is a given value
> + * @v: pointer of type atomic64_t
> + * @a: the amount to add to v...
> + * @u: ...unless v is equal to u.
> + *
> + * Atomically adds @a to @v, so long as it was not @u.
> + * Returns non-zero if @v was not @u, and zero otherwise.
> + */
> +#define atomic64_add_unless(v, a, u) \
> +({ \
> + __typeof__((v)->counter) c, old; \
> + c = atomic64_read(v); \
> + for (;;) { \
> + if (unlikely(c == (u))) \
> + break; \
> + old = atomic64_cmpxchg((v), c, c + (a)); \
> + if (likely(old == c)) \
> + break; \
> + c = old; \
> + } \
> + c != (u); \
> +})
> +#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
> +
> /* These are x86-specific, used by some header files */
> #define atomic_clear_mask(mask, addr) \
> __asm__ __volatile__(LOCK_PREFIX "andl %0,%1" \
>
>

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