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Commit cdc60a4c authored by Corey Minyard's avatar Corey Minyard Committed by Linus Torvalds
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[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: default avatarCorey Minyard <minyard@acm.org>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 5192d84e

arch/x86_64/kernel/traps.c

+9 −1
Original line number Diff line number Diff line
@@ -385,6 +385,7 @@ void out_of_line_bug(void) 


static DEFINE_SPINLOCK(die_lock);

static int die_owner = -1;

static unsigned int die_nest_count;



unsigned __kprobes long oops_begin(void)

{
@@ -399,6 +400,7 @@ unsigned __kprobes long oops_begin(void) 
		else

			spin_lock(&die_lock);

	}

	die_nest_count++;

	die_owner = cpu;

	console_verbose();

	bust_spinlocks(1);
@@ -409,6 +411,12 @@ void __kprobes oops_end(unsigned long flags) 
{ 

	die_owner = -1;

	bust_spinlocks(0);

	die_nest_count--;

	if (die_nest_count)

		/* We still own the lock */

		local_irq_restore(flags);

	else

		/* Nest count reaches zero, release the lock. */

		spin_unlock_irqrestore(&die_lock, flags);

	if (panic_on_oops)

		panic("Oops");