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 <ak@suse.de>
  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 <mingo@elte.hu>

1 files changed, 3 insertions, 4 deletions

diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index ef60102..c88bbff 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;