Re: in x86 architecture ,why the function atomic_sub_and_test() does not disable the interrupt?

From: Roland Dreier
Date: Tue Apr 06 2010 - 02:07:36 EST

> static inline int atomic_sub_and_test(int i, atomic_t *v)
> {
> unsigned char c;
> asm volatile(LOCK_PREFIX "subl %2,%0; sete %1"
> : "+m" (v->counter), "=qm" (c)
> : "ir" (i) : "memory");
> return c;
> }

Why would disabling interrupts be necessary? The LOCK_PREFIX makes the
subl atomic, and the sete just operates using the flag set by subl, so
it doesn't matter if any interrupts occur or not (since returning from
an interrupt must obviously restore flags).
Roland Dreier <rolandd@xxxxxxxxx> || For corporate legal information go to:
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