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    SubjectRe: [PATCH] udev enhancements to use kernel event queue
    Patrick Mochel writes:

    > It seems like the following should work. Would someone mind commenting on
    > it?

    > +/**
    > + * atomic_inc_and_read - increment atomic variable and return new value
    > + * @v: pointer of type atomic_t
    > + *
    > + * Atomically increments @v by 1. Note that the guaranteed
    > + * useful range of an atomic_t is only 24 bits.
    > + */
    > +static inline int atomic_inc_and_read(atomic_t *v)
    > +{
    > + __asm__ __volatile__(
    > + LOCK "incl %0"
    > + :"=m" (v->counter)
    > + :"m" (v->counter));
    > + return v->counter;
    > +}

    BZZZT. If another CPU is also doing atomic_inc_and_read you could end
    up with both calls returning the same value.

    You can't do atomic_inc_and_read on 386. You can on cpus that have
    cmpxchg (e.g. later x86). You can also on machines with load-locked
    and store-conditional instructions (alpha, ppc, probably most other
    RISCs).

    Paul.

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