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    Subject[PATCH] define have_arch_cmpxchg()
    define have_arch_cmpxchg()

    * Christoph Lameter (clameter@sgi.com) wrote:
    > If we really want to do this then the implementation of all of these
    > components need to result in competitive performance on all platforms.
    >
    Here is the first of 2 proposed patches to keep the same performances on
    architectures that does not implement cmpxchg_local.

    Add have_arch_cmpxchg(), which can be used within the body of functions to
    select between irq disable and local_cmpxchg.

    Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
    ---
    include/linux/hardirq.h | 6 ++++++
    1 file changed, 6 insertions(+)

    Index: slab/include/linux/hardirq.h
    ===================================================================
    --- slab.orig/include/linux/hardirq.h 2007-08-22 10:27:07.000000000 -0400
    +++ slab/include/linux/hardirq.h 2007-08-22 10:27:46.000000000 -0400
    @@ -149,4 +149,10 @@ extern void irq_exit(void);
    #define nmi_enter() do { lockdep_off(); __irq_enter(); } while (0)
    #define nmi_exit() do { __irq_exit(); lockdep_on(); } while (0)

    +#ifdef __HAVE_ARCH_CMPXCHG
    +#define have_arch_cmpxchg() 1
    +#else
    +#define have_arch_cmpxchg() 0
    +#endif
    +
    #endif /* LINUX_HARDIRQ_H */
    --
    Mathieu Desnoyers
    Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
    OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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