Messages in this thread | | | Subject | Re: [PATCH -rt 4/5] use migrate_disable for __local_begin | From | Peter Zijlstra <> | Date | Sat, 14 Jul 2007 19:32:22 +0200 |
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On Sat, 2007-07-14 at 13:16 -0400, Mathieu Desnoyers wrote: > * Peter Zijlstra (a.p.zijlstra@chello.nl) wrote: > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> > > --- > > include/asm-i386/local.h | 7 ++++--- > > include/asm-x86_64/local.h | 7 ++++--- > > 2 files changed, 8 insertions(+), 6 deletions(-) > > > > Index: linux-2.6/include/asm-i386/local.h > > =================================================================== > > --- linux-2.6.orig/include/asm-i386/local.h > > +++ linux-2.6/include/asm-i386/local.h > > @@ -197,11 +197,12 @@ static __inline__ long local_sub_return( > > #define __local_begin(__flags) \ > > { \ > > (__flags) = 0; \ > > - preempt_disable(); \ > > + migrate_disable(); \ > > Brrrr. That's wrong. Your non atomic __local*() updates only makes sense > when preempt_disable/enable() protects them from concurrent threads on > the same CPU, which is not the case of migrate_disable/enable(). This is > why I suggest that you use local_begin/end() mapped to > migrate_disable/enable() for normal local variables, and, if you really > want a __local_begin/end(), then it should be mapped to > preempt_disable/enable() and should state that it provides no protection > against interrupts.
Sure, but on -rt it does suffice, this part of the patch is rather WIP.
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