[POWERPC] Handle recursive oopses

Handle recursive oopses, like on x86. We had a few cases recently where
we locked up in oops printing and didnt make it into crashdump.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 36 insertions, 16 deletions

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 6297da743db9..55d221ffcf1e 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -108,42 +108,62 @@ static void pmac_backlight_unblank(void)
 static inline void pmac_backlight_unblank(void) { }
 #endif
 
-static DEFINE_SPINLOCK(die_lock);
-
 int die(const char *str, struct pt_regs *regs, long err)
 {
+        static struct {
+                spinlock_t lock;
+                u32 lock_owner;
+                int lock_owner_depth;
+        } die = {
+                .lock =                 __SPIN_LOCK_UNLOCKED(die.lock),
+                .lock_owner =           -1,
+                .lock_owner_depth =     0
+        };
         static int die_counter;
+        unsigned long flags;
 
         if (debugger(regs))
                 return 1;
 
         oops_enter();
 
-        console_verbose();
-        spin_lock_irq(&die_lock);
-        bust_spinlocks(1);
-        if (machine_is(powermac))
-                pmac_backlight_unblank();
+        if (die.lock_owner != raw_smp_processor_id()) {
+                console_verbose();
+                spin_lock_irqsave(&die.lock, flags);
+                die.lock_owner = smp_processor_id();
+                die.lock_owner_depth = 0;
+                bust_spinlocks(1);
+                if (machine_is(powermac))
+                        pmac_backlight_unblank();
+        } else {
+                local_save_flags(flags);
+        }
 
-        printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);
+        if (++die.lock_owner_depth < 3) {
+                printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);
 #ifdef CONFIG_PREEMPT
-        printk("PREEMPT ");
+                printk("PREEMPT ");
 #endif
 #ifdef CONFIG_SMP
-        printk("SMP NR_CPUS=%d ", NR_CPUS);
+                printk("SMP NR_CPUS=%d ", NR_CPUS);
 #endif
 #ifdef CONFIG_DEBUG_PAGEALLOC
-        printk("DEBUG_PAGEALLOC ");
+                printk("DEBUG_PAGEALLOC ");
 #endif
 #ifdef CONFIG_NUMA
-        printk("NUMA ");
+                printk("NUMA ");
 #endif
-        printk("%s\n", ppc_md.name ? "" : ppc_md.name);
+                printk("%s\n", ppc_md.name ? "" : ppc_md.name);
+
+                print_modules();
+                show_regs(regs);
+        } else {
+                printk("Recursive die() failure, output suppressed\n");
+        }
 
-        print_modules();
-        show_regs(regs);
         bust_spinlocks(0);
-        spin_unlock_irq(&die_lock);
+        die.lock_owner = -1;
+        spin_unlock_irqrestore(&die.lock, flags);
 
         if (kexec_should_crash(current) ||
                 kexec_sr_activated(smp_processor_id()))