From: Ingo Molnar Date: Fri, 21 Dec 2007 00:27:19 +0000 (+0100) Subject: x86: fix die() to not be preemptible X-Git-Tag: firefly_0821_release~23937^2~1 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=c0a698b7443a9fce76b0a849f06c45ac78f3b0a0;p=firefly-linux-kernel-4.4.55.git x86: fix die() to not be preemptible Andrew "Eagle Eye" Morton noticed that we use raw_local_save_flags() instead of raw_local_irq_save(flags) in die(). This allows the preemption of oopsing contexts - which is highly undesirable. It also causes CONFIG_DEBUG_PREEMPT to complain, as reported by Miles Lane. this bug was introduced via: commit 39743c9ef717fd4f2b5583f010115c5f2482b8ae Author: Andi Kleen Date: Fri Oct 19 20:35:03 2007 +0200 x86: use raw locks during oopses - spin_lock_irqsave(&die.lock, flags); + __raw_spin_lock(&die.lock); + raw_local_save_flags(flags); that is not a correct open-coding of spin_lock_irqsave(): both the ordering is wrong (irqs should be disabled _first_), and the wrong flags-saving API was used. Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c index ef6010262597..c88bbffcaa03 100644 --- a/arch/x86/kernel/traps_32.c +++ b/arch/x86/kernel/traps_32.c @@ -373,14 +373,13 @@ void die(const char * str, struct pt_regs * regs, long err) 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;