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    SubjectRe: [PATCH v9 3/5] qrwlock, x86 - Treat all data type not bigger than long as atomic in x86
    On 01/20/2014 10:03 AM, Peter Zijlstra wrote:
    > On Tue, Jan 14, 2014 at 11:44:05PM -0500, Waiman Long wrote:
    >> The generic __native_word() macro defined in include/linux/compiler.h
    >> only allows "int" and "long" data types to be treated as native and
    >> atomic. The x86 architecture, however, allow the use of char and short
    >> data types as atomic as well.
    >>
    >> This patch extends the data type allowed in the __native_word() macro to
    >> allow the use of char and short.
    >>
    >> Signed-off-by: Waiman Long<Waiman.Long@hp.com>
    >> ---
    >> arch/x86/include/asm/barrier.h | 8 ++++++++
    >> 1 files changed, 8 insertions(+), 0 deletions(-)
    >>
    >> diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
    >> index 04a4890..4d3e30a 100644
    >> --- a/arch/x86/include/asm/barrier.h
    >> +++ b/arch/x86/include/asm/barrier.h
    >> @@ -24,6 +24,14 @@
    >> #define wmb() asm volatile("sfence" ::: "memory")
    >> #endif
    >>
    >> +/*
    >> + * All data types<= long are atomic in x86
    >> + */
    >> +#ifdef __native_word
    >> +#undef __native_word
    >> +#endif
    >> +#define __native_word(t) (sizeof(t)<= sizeof(long))
    > Yeah, not going to happen.

    Does explicit list of acceptable sizes work for you?

    #define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) ==
    sizeof(short) || sizeof(t) == sizeof(int ) ||
    sizeof(t) == sizeof(long))

    -Longman


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