Pravin Nanaware wrote:
Hi,
I was just going through the include file in the /usr/include/asm/bitops.h
The function description describes it as non-atomic but it seems it is not.
static __inline__ void __change_bit(int nr, volatile void * addr)
{
__asm__ __volatile__(
"btcl %1,%0"
:"=m" (ADDR)
:"Ir" (nr));
}
The kernel version I am using is 2.6.9-42. Is it right or am I missing something ?
Thanks,
Pravin
The bitops.h comments are correct: the btc IA-32 instruction is only
atomic if used with the lock prefix. The function above does not use the
lock prefix, so it is not atomic.
thanks,
John Hubbard
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