i386, dumpstack: use x86_64's method to account die_nest_count

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>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index a29b88ffa346c0d14088565a34c9f356a9894a7f..7c7d691b32be250d89ec6f730c4b4835043f04a4 100644 (file)
--- 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)