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    Subject[patch 09/28] Add cmpxchg_local to blackfin, replace __cmpxchg by generic cmpxchg
    Use the new generic cmpxchg_local (disables interrupt). Also use the generic
    cmpxchg as fallback if SMP is not set since nobody seems to know why __cmpxchg
    has been implemented in assembly in the first place thather than in plain C.

    Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
    CC: clameter@sgi.com
    CC: michael.frysinger@analog.com
    ---
    include/asm-blackfin/system.h | 59 ++++++++----------------------------------
    1 file changed, 12 insertions(+), 47 deletions(-)

    Index: linux-2.6-lttng/include/asm-blackfin/system.h
    ===================================================================
    --- linux-2.6-lttng.orig/include/asm-blackfin/system.h 2007-08-07 14:31:52.000000000 -0400
    +++ linux-2.6-lttng/include/asm-blackfin/system.h 2007-08-07 14:47:31.000000000 -0400
    @@ -176,55 +176,20 @@ static inline unsigned long __xchg(unsig
    return tmp;
    }

    +#include <asm-generic/cmpxchg-local.h>
    +
    /*
    - * Atomic compare and exchange. Compare OLD with MEM, if identical,
    - * store NEW in MEM. Return the initial value in MEM. Success is
    - * indicated by comparing RETURN with OLD.
    + * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
    + * them available.
    */
    -static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
    - unsigned long new, int size)
    -{
    - unsigned long tmp = 0;
    - unsigned long flags = 0;
    -
    - local_irq_save(flags);
    -
    - switch (size) {
    - case 1:
    - __asm__ __volatile__
    - ("%0 = b%3 (z);\n\t"
    - "CC = %1 == %0;\n\t"
    - "IF !CC JUMP 1f;\n\t"
    - "b%3 = %2;\n\t"
    - "1:\n\t"
    - : "=&d" (tmp) : "d" (old), "d" (new), "m" (*__xg(ptr)) : "memory");
    - break;
    - case 2:
    - __asm__ __volatile__
    - ("%0 = w%3 (z);\n\t"
    - "CC = %1 == %0;\n\t"
    - "IF !CC JUMP 1f;\n\t"
    - "w%3 = %2;\n\t"
    - "1:\n\t"
    - : "=&d" (tmp) : "d" (old), "d" (new), "m" (*__xg(ptr)) : "memory");
    - break;
    - case 4:
    - __asm__ __volatile__
    - ("%0 = %3;\n\t"
    - "CC = %1 == %0;\n\t"
    - "IF !CC JUMP 1f;\n\t"
    - "%3 = %2;\n\t"
    - "1:\n\t"
    - : "=&d" (tmp) : "d" (old), "d" (new), "m" (*__xg(ptr)) : "memory");
    - break;
    - }
    - local_irq_restore(flags);
    - return tmp;
    -}
    -
    -#define cmpxchg(ptr,o,n)\
    - ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
    - (unsigned long)(n),sizeof(*(ptr))))
    +#define cmpxchg_local(ptr,o,n) \
    + (__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o), \
    + (unsigned long)(n), sizeof(*(ptr)))
    +#define cmpxchg64_local(ptr,o,n) __cmpxchg64_local_generic((ptr), (o), (n))
    +
    +#ifndef CONFIG_SMP
    +#include <asm-generic/cmpxchg.h>
    +#endif

    #define prepare_to_switch() do { } while(0)

    --
    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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