[PATCH] kdump: sysrq trigger mechanism for kexec based crashdumps

Add a sysrq-trigger mechanism for kexec based crashdumps.  Alt-Sysrq-c
triggers a kexec based crashdump.

Signed-off-by: Hariprasad Nellitheertha <hari@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 22 insertions, 2 deletions

diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index f59f7cbd525b..53b2c8fab00e 100644
--- a/drivers/char/sysrq.c
+++ b/drivers/char/sysrq.c
@@ -35,6 +35,7 @@
 #include <linux/spinlock.h>
 #include <linux/vt_kern.h>
 #include <linux/workqueue.h>
+#include <linux/kexec.h>
 
 #include <asm/ptrace.h>
 
@@ -94,6 +95,21 @@ static struct sysrq_key_op sysrq_unraw_op = {
 };
 #endif /* CONFIG_VT */
 
+#ifdef CONFIG_KEXEC
+/* crashdump sysrq handler */
+static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
+                                struct tty_struct *tty)
+{
+        crash_kexec();
+}
+static struct sysrq_key_op sysrq_crashdump_op = {
+        .handler        = sysrq_handle_crashdump,
+        .help_msg       = "Crashdump",
+        .action_msg     = "Trigger a crashdump",
+        .enable_mask    = SYSRQ_ENABLE_DUMP,
+};
+#endif
+
 /* reboot sysrq handler */
 static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
                                 struct tty_struct *tty) 
@@ -273,8 +289,12 @@ static struct sysrq_key_op *sysrq_key_table[SYSRQ_KEY_TABLE_LENGTH] = {
                  it is handled specially on the sparc
                  and will never arrive */
 /* b */ &sysrq_reboot_op,
-/* c */ NULL,
-/* d */ NULL,
+#ifdef CONFIG_KEXEC
+/* c */ &sysrq_crashdump_op,
+#else
+/* c */ NULL,
+#endif
+/* d */ NULL,
 /* e */ &sysrq_term_op,
 /* f */ &sysrq_moom_op,
 /* g */ NULL,