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SubjectRe: gnu asm help...
On 18 Jun 01 at 18:20, Timur Tabi wrote:
> You want to return the variable? Try this:
> static __inline__ unsigned long atomic_inc(atomic_t *v)
> {
> __asm__ __volatile__(
> LOCK "incl %0"
> :"=m" (v->counter)
> :"m" (v->counter));
> return v->counter;
> }

No. Another CPU might increment value between LOCK INCL and
fetching v->counter. On ia32 architecture you are almost out of
luck. You can either try building atomic_inc around CMPXCHG,
using it as conditional store (but CMPXCHG is not available
on i386), or you can just guard your atomic variable with
spinlock - but in that case there is no reason for using atomic_t
at all.
Best regards,
Petr Vandrovec

P.S.: Why you need to know that value? You can either rewrite
your code with atomic_dec_and_test/atomic_inc_and_test, or
you overlooked some race, or you have really strange problem.
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