Messages in this thread | | | Date | Wed, 24 Jan 2007 12:00:22 -0500 | From | Mathieu Desnoyers <> | Subject | Re: [PATCH 7/10] local_t : powerpc |
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* Paul Mackerras (paulus@samba.org) wrote: > Mathieu Desnoyers writes: > > > +static __inline__ int local_dec_if_positive(local_t *l) > > +{ > > + int t; > > + > > + __asm__ __volatile__( > > +"1: lwarx %0,0,%1 # local_dec_if_positive\n\ > > + addic. %0,%0,-1\n\ > > + blt- 2f\n" > > + PPC405_ERR77(0,%1) > > +" stwcx. %0,0,%1\n\ > > + bne- 1b" > > This has the same bugs that we fixed recently in atomic_dec_if_positive; > first, on 64-bit machines, the lwarx will zero-extend the word loaded > from memory, and so the result of the addic will be negative only if > the word was originally 0. Secondly, even on 32-bit machines, > 0x80000000 will be considered positive since decrementing it gives > 0x7fffffff, which is positive. > Hi Paul,
Thanks, will fix.
Mathieu
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