On Fri, 28 Sep 2007 11:18:45 +0200 Laurent Vivier <[EMAIL PROTECTED]> wrote:
> Andrew Morton wrote: > > On Fri, 28 Sep 2007 10:52:08 +0200 Laurent Vivier <[EMAIL PROTECTED]> wrote: > >> > >> Andi, is this correct ? > >> Andrew, should I send a patch implementing this change ? > > > > umm, I think all the smp_call_function fucntions are deadlocky if called > > with local interrupts disabled, regardless of whether the calling CPU is in > > the mask. > > > > If CPU A is sending a cross-cpu call to CPU B and CPU B is sending a > > cross-cpu call to CPU A, and they both have local interrupts disabled... > > OK, so there are two errors: > > 1- one I introduce myself (without any help from anyone) where > smp_call_function() calls all online CPUs instead of calling all CPUs except > itself. I'd be pretty surprised if one was able to write a bug like that. You mean the CPU sends an IPI to itself and then loops around until it has serviced that IPI? And this works? Wow. And on_each_cpu() can call the handler function twice? hm > 2- one in global_flush_tlb() which calls smp_call_function() with irqs > disabled. That would be a big bug, and surely we would already have picked it up. <looks> argh, mainline's x86_64 smp_call_function() doesn't do the check. We've had *heaps* of bugs in i386 where people were running smp_call_foo() under local_irq_disable(). I wonder how many there are in x86_64? > I think I should at least correct #1 ? I think we should correct all bugs ;) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
