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Subject[PATCH 5/7] i386, dumpstack: use x86_64's method to account die_nest_count
Date
oops_begin/oops_end should always be used in pairs. On x86_64
oops_begin increments die_nest_count, and oops_end decrements
die_nest_count. Doing this makes oops_begin and oops_end equal
to the x86_64 versions.

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
---
arch/x86/kernel/dumpstack_32.c | 29 +++++++++++++++++------------
1 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index a29b88f..7c7d691 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -289,21 +289,24 @@ static unsigned int die_nest_count;

unsigned __kprobes long oops_begin(void)
{
+ int cpu;
unsigned long flags;

oops_enter();

- if (die_owner != raw_smp_processor_id()) {
- console_verbose();
- raw_local_irq_save(flags);
- __raw_spin_lock(&die_lock);
- die_owner = smp_processor_id();
- die_nest_count = 0;
- bust_spinlocks(1);
- } else {
- raw_local_irq_save(flags);
+ /* racy, but better than risking deadlock. */
+ raw_local_irq_save(flags);
+ cpu = smp_processor_id();
+ if (!__raw_spin_trylock(&die_lock)) {
+ if (cpu == die_owner)
+ /* nested oops. should stop eventually */;
+ else
+ __raw_spin_lock(&die_lock);
}
die_nest_count++;
+ die_owner = cpu;
+ console_verbose();
+ bust_spinlocks(1);
return flags;
}

@@ -315,13 +318,15 @@ void __kprobes oops_end(unsigned long flags, struct pt_regs *regs, int signr)
bust_spinlocks(0);
die_owner = -1;
add_taint(TAINT_DIE);
- __raw_spin_unlock(&die_lock);
+ die_nest_count--;
+ if (!die_nest_count)
+ /* Nest count reaches zero, release the lock. */
+ __raw_spin_unlock(&die_lock);
raw_local_irq_restore(flags);
-
oops_exit();
+
if (!signr)
return;
-
if (in_interrupt())
panic("Fatal exception in interrupt");
if (panic_on_oops)
--
1.5.4.3


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