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-rw-r--r--Documentation/sysrq.txt2
-rw-r--r--drivers/char/sysrq.c46
2 files changed, 48 insertions, 0 deletions
diff --git a/Documentation/sysrq.txt b/Documentation/sysrq.txt
index 10c8f6922ef..5ce0952aa06 100644
--- a/Documentation/sysrq.txt
+++ b/Documentation/sysrq.txt
@@ -85,6 +85,8 @@ On all - write a character to /proc/sysrq-trigger. e.g.:
'k' - Secure Access Key (SAK) Kills all programs on the current virtual
console. NOTE: See important comments below in SAK section.
+'l' - Shows a stack backtrace for all active CPUs.
+
'm' - Will dump current memory info to your console.
'n' - Used to make RT tasks nice-able
diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index 1ade193c912..9e9bad8bdcf 100644
--- a/drivers/char/sysrq.c
+++ b/drivers/char/sysrq.c
@@ -196,6 +196,48 @@ static struct sysrq_key_op sysrq_showlocks_op = {
#define sysrq_showlocks_op (*(struct sysrq_key_op *)0)
#endif
+#ifdef CONFIG_SMP
+static DEFINE_SPINLOCK(show_lock);
+
+static void showacpu(void *dummy)
+{
+ unsigned long flags;
+
+ /* Idle CPUs have no interesting backtrace. */
+ if (idle_cpu(smp_processor_id()))
+ return;
+
+ spin_lock_irqsave(&show_lock, flags);
+ printk(KERN_INFO "CPU%d:\n", smp_processor_id());
+ show_stack(NULL, NULL);
+ spin_unlock_irqrestore(&show_lock, flags);
+}
+
+static void sysrq_showregs_othercpus(struct work_struct *dummy)
+{
+ smp_call_function(showacpu, NULL, 0, 0);
+}
+
+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);
+ }
+ schedule_work(&sysrq_showallcpus);
+}
+
+static struct sysrq_key_op sysrq_showallcpus_op = {
+ .handler = sysrq_handle_showallcpus,
+ .help_msg = "aLlcpus",
+ .action_msg = "Show backtrace of all active CPUs",
+ .enable_mask = SYSRQ_ENABLE_DUMP,
+};
+#endif
+
static void sysrq_handle_showregs(int key, struct tty_struct *tty)
{
struct pt_regs *regs = get_irq_regs();
@@ -340,7 +382,11 @@ static struct sysrq_key_op *sysrq_key_table[36] = {
&sysrq_kill_op, /* i */
NULL, /* j */
&sysrq_SAK_op, /* k */
+#ifdef CONFIG_SMP
+ &sysrq_showallcpus_op, /* l */
+#else
NULL, /* l */
+#endif
&sysrq_showmem_op, /* m */
&sysrq_unrt_op, /* n */
/* o: This will often be registered as 'Off' at init time */