kdb,debug_core: Allow the debug core to receive a panic notification

It is highly desirable to trap into kdb on panic. The debug core will attempt to register as the first in line for the panic notifier. CC: Ingo Molnar <[email protected]> CC: Andrew Morton <[email protected]> CC: Eric W. Biederman <[email protected]> Signed-off-by: Jason Wessel <[email protected]>
mgowda · May 21, 2010 · 4402c15 · 4402c15
1 parent 5b778da
commit 4402c15
Showing 1 changed file with 19 additions and 0 deletions.
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
@@ -762,11 +762,28 @@ static struct sysrq_key_op sysrq_dbg_op = {
 };
 #endif
 
+static int kgdb_panic_event(struct notifier_block *self,
+			    unsigned long val,
+			    void *data)
+{
+	if (dbg_kdb_mode)
+		kdb_printf("PANIC: %s\n", (char *)data);
+	kgdb_breakpoint();
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block kgdb_panic_event_nb = {
+       .notifier_call	= kgdb_panic_event,
+       .priority	= INT_MAX,
+};
+
 static void kgdb_register_callbacks(void)
 {
 	if (!kgdb_io_module_registered) {
 		kgdb_io_module_registered = 1;
 		kgdb_arch_init();
+		atomic_notifier_chain_register(&panic_notifier_list,
+					       &kgdb_panic_event_nb);
 #ifdef CONFIG_MAGIC_SYSRQ
 		register_sysrq_key('g', &sysrq_dbg_op);
 #endif
@@ -786,6 +803,8 @@ static void kgdb_unregister_callbacks(void)
 	 */
 	if (kgdb_io_module_registered) {
 		kgdb_io_module_registered = 0;
+		atomic_notifier_chain_unregister(&panic_notifier_list,
+					       &kgdb_panic_event_nb);
 		kgdb_arch_exit();
 #ifdef CONFIG_MAGIC_SYSRQ
 		unregister_sysrq_key('g', &sysrq_dbg_op);