[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>
diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 2700b13..0ebb281 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -385,6 +385,7 @@
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 @@
else
spin_lock(&die_lock);
}
+ die_nest_count++;
die_owner = cpu;
console_verbose();
bust_spinlocks(1);
@@ -409,7 +411,13 @@
{
die_owner = -1;
bust_spinlocks(0);
- spin_unlock_irqrestore(&die_lock, flags);
+ 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");
}