[PATCH] x86_64: fix die_lock nesting
I noticed this when poking around in this area. The oops_begin() function in x86_64 would only conditionally claim the die_lock if the call is nested, but oops_end() would always release the spinlock. This patch adds a nest count for the die lock so that the release of the lock is only done on the final oops_end(). Signed-off-by: Corey Minyard <minyard@acm.org> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -385,6 +385,7 @@ void out_of_line_bug(void)
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static DEFINE_SPINLOCK(die_lock);
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static int die_owner = -1;
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static unsigned int die_nest_count;
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unsigned __kprobes long oops_begin(void)
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{
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@ -399,6 +400,7 @@ unsigned __kprobes long oops_begin(void)
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else
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spin_lock(&die_lock);
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}
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die_nest_count++;
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die_owner = cpu;
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console_verbose();
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bust_spinlocks(1);
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@ -409,7 +411,13 @@ void __kprobes oops_end(unsigned long flags)
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{
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die_owner = -1;
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bust_spinlocks(0);
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spin_unlock_irqrestore(&die_lock, flags);
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die_nest_count--;
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if (die_nest_count)
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/* We still own the lock */
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local_irq_restore(flags);
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else
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/* Nest count reaches zero, release the lock. */
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spin_unlock_irqrestore(&die_lock, flags);
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if (panic_on_oops)
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panic("Oops");
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}
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