sysrq: add show-backtrace-on-all-cpus function

[cascardo/linux.git] / drivers / char / sysrq.c

diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index 1ade193..9e9bad8 100644 (file)
--- 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 */