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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 39743c9ef7
  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>
This commit is contained in:
Ingo Molnar 2007-12-21 01:27:19 +01:00
parent faa4877f02
commit c0a698b744
1 changed files with 3 additions and 4 deletions
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7
arch/x86/kernel/traps_32.c
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@ -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;