Messages in this thread | | | Date | Thu, 29 May 2008 22:38:25 -0700 | From | Andrew Morton <> | Subject | Re: [patch 04/41] cpu ops: Core piece for generic atomic per cpu operations |
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On Thu, 29 May 2008 22:17:55 -0700 (PDT) Christoph Lameter <clameter@sgi.com> wrote:
> > > local_t is also very specific to the x86 processor. > > > > And alpha, m32r, mips and powerpc, methinks. Probably others, but > > people just haven't got around to it. > > No local_t does not do the relocation of the address to the correct percpu > 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.
> > I think I'll need to come back another time to understand all that ;) > > > > Thanks for writing it up carefully. > > Well this stuff is so large in scope that I have difficulties keeping > everything straight. > > > I wonder if all this stuff should be in a new header file. > > > > We could get lazy and include that header from percpu.h if needed. > > But then its related to percpu operations and relies extensively on the > various percpu.h files in asm-generic and asm-arch and include/linux
Well that should be fixed. We should never have mixed the alloc_percpu() and DEFINE_PER_CPU things inthe same header. They're different.
otoh as you propose removing the old alloc_percpu() I guess the end result is no worse than what we presently have.
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