Merge branch 'core-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'core-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  debug lockups: Improve lockup detection, fix generic arch fallback
  debug lockups: Improve lockup detection

1 files changed, 14 insertions, 5 deletions

diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index 5d7a02f63e1c..50eecfe1d724 100644
--- a/drivers/char/sysrq.c
+++ b/drivers/char/sysrq.c
@@ -24,6 +24,7 @@
 #include <linux/sysrq.h>
 #include <linux/kbd_kern.h>
 #include <linux/proc_fs.h>
+#include <linux/nmi.h>
 #include <linux/quotaops.h>
 #include <linux/perf_counter.h>
 #include <linux/kernel.h>
@@ -222,12 +223,20 @@ static DECLARE_WORK(sysrq_showallcpus, sysrq_showregs_othercpus);
 
 static void sysrq_handle_showallcpus(int key, struct tty_struct *tty)
 {
-        struct pt_regs *regs = get_irq_regs();
-        if (regs) {
-                printk(KERN_INFO "CPU%d:\n", smp_processor_id());
-                show_regs(regs);
+        /*
+         * Fall back to the workqueue based printing if the
+         * backtrace printing did not succeed or the
+         * architecture has no support for it:
+         */
+        if (!trigger_all_cpu_backtrace()) {
+                struct pt_regs *regs = get_irq_regs();
+
+                if (regs) {
+                        printk(KERN_INFO "CPU%d:\n", smp_processor_id());
+                        show_regs(regs);
+                }
+                schedule_work(&sysrq_showallcpus);
         }
-        schedule_work(&sysrq_showallcpus);
 }
 
 static struct sysrq_key_op sysrq_showallcpus_op = {