Messages in this thread Patch in this message | | | Date | Fri, 21 Dec 2007 01:30:35 +0100 | From | Ingo Molnar <> | Subject | Re: Linux 2.6.24-rc5 x86 architecture no longer Oopses... |
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* Andrew Morton <akpm@linux-foundation.org> wrote:
> On Fri, 21 Dec 2007 00:47:59 +0100 > Ingo Molnar <mingo@elte.hu> wrote: > > > > __raw_spin_lock(&die.lock); > > > raw_local_save_flags(flags); > > > - die.lock_owner = smp_processor_id(); > > > + die.lock_owner = raw_smp_processor_id(); > > > > we just disabled irqs with raw_local_save_flags(). > > <chases x86 spaghetti for a while> > > raw_local_save_flags() doesn't disable interrupts?
argh. Indeed! (I wanted us to fix that misleading name eons ago, to *_save_flags_only(), but some stupid bikeshed painting discussion prevented it from ever happening.)
that should have been raw_local_irq_save(flags)!
but ... why is it done like that? Why do we first take the die.lock and disable interrupts afterwards? It's highly weird. 64-bit does it all correctly in traps_64.c, so unification will help us out - but so far perhaps the patch below we should do in 2.6.24?
Ingo
------------> Subject: x86: fix die() to not be preemptible From: Ingo Molnar <mingo@elte.hu>
Andrew "Eagle Eye" Morton noticed that we use raw_local_save_flags() instead of raw_local_irq_save(flags) in die().
do it correctly - and first disable interrupts, then take the spinlock.
Signed-off-by: Ingo Molnar <mingo@elte.hu> --- arch/x86/kernel/traps_32.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)
Index: linux-x86.q/arch/x86/kernel/traps_32.c =================================================================== --- linux-x86.q.orig/arch/x86/kernel/traps_32.c +++ linux-x86.q/arch/x86/kernel/traps_32.c @@ -373,14 +373,13 @@ void die(const char * str, struct pt_reg if (die.lock_owner != raw_smp_processor_id()) { console_verbose(); + raw_local_irq_save(flags); __raw_spin_lock(&die.lock); - raw_local_save_flags(flags); die.lock_owner = smp_processor_id(); die.lock_owner_depth = 0; bust_spinlocks(1); - } - else - raw_local_save_flags(flags); + } else + raw_local_irq_save(flags); if (++die.lock_owner_depth < 3) { unsigned long esp;
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