On Tue, 2008-06-10 at 08:47 -0700, Paul E. McKenney wrote: > On Tue, Jun 10, 2008 at 03:51:25PM +0100, Catalin Marinas wrote: > > I was thinking whether this condition can be removed and allow the > > smp_call_function*() to be called with IRQs disabled. At a quick look, > > it seems to be possible if the csd_flag_wait() function calls the IPI > > handlers directly when the IRQs are disabled (see the patch below). [...] > There were objections last month: http://lkml.org/lkml/2008/5/3/167 Thanks, I missed this discussion. > The issue was that this permits some interrupts to arrive despite > interrupts being disabled. There seemed to be less resistance to > doing this in the wait==1 case, however. The "(wait == 1) && irqs_disabled()" case is what I would be interested in. In the patch you proposed, this doesn't seem to be allowed (at least from the use of WARN_ON). However, from your post in May: > 5. If you call smp_call_function() with irqs disabled, then you > are guaranteed that no other CPU's smp_call_function() handler > will be invoked while smp_call_function() is executing. this would be possible but no one need this functionality yet. Would one use-case (ARM SMP and DMA cache maintenance) be enough to implement this or I should add it to the ARM-specific code? Thanks. -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
