Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [patch 04/41] cpu ops: Core piece for generic atomic per cpu operations | Date | Fri, 30 May 2008 17:08:50 +1000 |
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On Friday 30 May 2008 16:12:59 Christoph Lameter wrote: > On Thu, 29 May 2008, Andrew Morton wrote: > > > area. It requies disabling of interrupts etc. > > > > No it doesn't. Look: > > > > static inline void local_inc(local_t *l) > > { > > asm volatile(_ASM_INC "%0" > > > > : "+m" (l->a.counter)); > > > > } > > > > > Its not atomic (wrt > > > interrupts) because of that. > > > > Yes it is. > > No its not! In order to increment a per cpu value you need to calculate > the per cpu pointer address in the current per cpu segment.
Christoph, you just missed it, that's all. Look at cpu_local_read et al in include/asm-i386/local.h (ie. before the x86 mergers chose the lowest common denominator one).
Cheers, Rusty.
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