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    SubjectRe: [x86] Unify semaphore_32.S and rwlock_64.S
    On 01/20/2010 04:46 PM, Linus Torvalds wrote:
    >
    >
    > On Wed, 20 Jan 2010, Linus Torvalds wrote:
    >>
    >> #define RWSEM_UNLOCKED_VALUE 0x00000000
    >> #define RWSEM_ACTIVE_BIAS 0x00000001
    >> #define RWSEM_ACTIVE_MASK 0x3fffffff
    >> #define RWSEM_WAITING_BIAS (~RWSEM_ACTIVE_MASK)
    >> #define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
    >> #define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
    >
    > Btw, doing that RWSEM_WAITING_BIAS cleanup (we currently have it as an
    > independent constant) means that now all constants are shared except for
    > that RWSEM_ACTIVE_MASK. So it ends up being something like this:
    >
    > #ifdef CONFIG_RWSEM_64bit
    > typedef __s64 rwsem_count_t;
    > #define RWSEM_ACTIVE_MASK 0x3fffffff
    > #else
    > typedef __s32 rwsem_count_t;
    > #define RWSEM_ACTIVE_MASK 0xffff
    > #endif
    >
    > #define RWSEM_UNLOCKED_VALUE 0x00000000
    > #define RWSEM_ACTIVE_BIAS 0x00000001
    > #define RWSEM_WAITING_BIAS (~RWSEM_ACTIVE_MASK)
    > #define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
    > #define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
    >
    > with just that two-line difference for the 32-bit/64-bit case.
    >
    > At least I _think_ so.
    >

    Yes, I already had that change in my tree (or rather, I wrote it as
    (-RWSEM_ACTIVE_MASK-1) to be consistent with what was previously there,
    but (~RWSEM_ACTIVE_MASK) makes more sense.)

    > And it's worth noting (again) that I didn't actually push the
    > twsem_count_t changes down into the slow-path code in lib/rwsem.c. There's
    > a few variables there that might need looking at too. I _think_ they are
    > all ok as-is (unlike the header file, lib/rwsem.c seems to consistently
    > use 'signed long' rather than mix 32-bit and 64-bit types), but it migh be
    > cleaner to make them rwsem_count_t's too.

    Yes, if we have it we should it consistently.

    -hpa



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