[PATCH] x86: all cpu backtrace

When a spinlock lockup occurs, arrange for the NMI code to emit an all-cpu
backtrace, so we get to see which CPU is holding the lock, and where.

Cc: Andi Kleen <ak@muc.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index e16904e28c3a..acb4ed130247 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -15,9 +15,14 @@
  * disables interrupts for a long time. This call is stateless.
  */
 #ifdef ARCH_HAS_NMI_WATCHDOG
+#include <asm/nmi.h>
 extern void touch_nmi_watchdog(void);
 #else
 # define touch_nmi_watchdog() touch_softlockup_watchdog()
 #endif
 
+#ifndef trigger_all_cpu_backtrace
+#define trigger_all_cpu_backtrace() do { } while (0)
+#endif
+
 #endif