Date: Tue, 17 Oct 2006 16:48:37 -0400
From: Larry Woodman <lwoodman@redhat.com>
Subject: Re: [RHEL5 patch] add "<Alt> <Sys> w " functionality to RHEL5/FC6


--- linux-2.6.18.noarch/drivers/char/sysrq.c.orig
+++ linux-2.6.18.noarch/drivers/char/sysrq.c
@@ -203,6 +203,25 @@ static struct sysrq_key_op sysrq_showmem
 	.enable_mask	= SYSRQ_ENABLE_DUMP,
 };
 
+static spinlock_t show_lock = SPIN_LOCK_UNLOCKED;
+static void showacpu(void *info)
+{
+	spin_lock(&show_lock);
+	printk("CPU%d:\n", smp_processor_id());
+	show_stack(NULL, NULL);
+	spin_unlock(&show_lock);
+}
+static void sysrq_handle_showcpus(int key, struct pt_regs *pt_regs,
+				  struct tty_struct *tty) {
+	on_each_cpu(showacpu, NULL, 0, 0);
+}
+static struct sysrq_key_op sysrq_showcpus_op = {
+	.handler	= sysrq_handle_showcpus,
+	.help_msg	= "shoWcpus",
+	.action_msg	= "Show CPUs",
+	.enable_mask	= SYSRQ_ENABLE_DUMP,
+};
+
 /*
  * Signal sysrq helper function.  Sends a signal to all user processes.
  */
@@ -317,7 +340,7 @@ static struct sysrq_key_op *sysrq_key_ta
 	&sysrq_mountro_op,		/* u */
 	/* May be assigned at init time by SMP VOYAGER */
 	NULL,				/* v */
-	NULL,				/* w */
+	&sysrq_showcpus_op,		/* w */
 	NULL,				/* x */
 	NULL,				/* y */
 	NULL				/* z */