Re: [PATCH] __up_read and gcc-3.0
Petr Vandrovec (VANDROVE@vc.cvut.cz)
Fri, 11 May 2001 15:48:39 MET-1
On 11 May 01 at 9:13, Tom Leete wrote:
> > __asm__ __volatile__(
> > "# beginning __up_read\n\t"
> > + " movl %2,%%edx\n\t"
> > LOCK_PREFIX " xadd %%edx,(%%eax)\n\t" /* subtracts 1, returns the old value */
> > " js 2f\n\t" /* jump if the lock is being waited upon */
> > "1:\n\t"
> My solution to this was to relax +d(tmp) to +m(tmp). Posted a few days ago.
> I have larger problems with 2.4.5-pre1 and have not gone back to check what
> comes out. Being a product of pure reason (and not much of that), mine
> deserves suspicion.
Changing +d => +m could generate 'xadd (%%xyz),(%%eax)' which does not exist.
Maybe +r, but in this case do not forget to add push/pop %%edx around
call to rwsem_wake. Otherwise you can have some corruption if gcc decides
to use %edx for some local variable around __up_read.
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