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    SubjectRe: [patch 1/3] spinlock fix #1, *_can_lock() primitives

    * Linus Torvalds <> wrote:

    > I can do ppc64 myself, can others fix the other architectures (Ingo,
    > shouldn't the UP case have the read/write_can_lock() cases too? And
    > wouldn't you agree that it makes more sense to have the rwlock test
    > variants in asm/rwlock.h?):

    You are right about UP, and the patch below adds the UP variants. It's
    analogous to the existing wrapping concept that UP 'spinlocks' are
    always unlocked on UP. (spin_can_lock() is already properly defined on
    UP too.)


    Signed-off-by: Ingo Molnar <>

    --- linux/include/linux/spinlock.h.orig
    +++ linux/include/linux/spinlock.h
    @@ -228,6 +228,9 @@ typedef struct {

    #define rwlock_yield(lock) (void)(lock)

    +#define read_can_lock(lock) (((void)(lock), 1))
    +#define write_can_lock(lock) (((void)(lock), 1))
    #define _spin_trylock(lock) ({preempt_disable(); _raw_spin_trylock(lock) ? \
    1 : ({preempt_enable(); 0;});})

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      Last update: 2005-03-22 14:09    [W:0.020 / U:10.380 seconds]
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