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    SubjectRe: inconsistent usage of
    On Tue, Apr 22 2003, wrote:
    > I found inconsistent behavoir between SMP oand none SMP kernels using spin
    > locks inside driver programming
    > As first an simple example:
    > static spinlock_t qtlock = SPIN_LOCK_UNLOCKED;
    > void foo()
    > {
    > unsigned long local_flags;
    > spin_lock_irqsave (&qtlock, local_flags);
    > spin_lock_irqsave (&qtlock, local_flags);
    > }

    [snip rant]

    Check the spinlock implementation. All the above does in UP is
    disable/save interrupts twice. The actual spinlock is a nop. As only one
    processor can be executing inside the kernel in UP, you only need to
    guard against interrupts.

    Jens Axboe

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