[IA64] kdump: add kdump_on_fatal_mca

While it is convenient that we can invoke kdump by asserting INIT
via button on chassis etc., there are some situations that invoking
kdump on fatal MCA is not welcomed rather than rebooting fast without
dump.

This patch adds a new flag 'kdump_on_fatal_mca' that is independent
from 'kdump_on_init' currently available.  Adding this flag enable
us to turning on/off of kdump depend on the event, INIT and/or fatal
MCA.  Default for this flag is to take the dump.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/kernel/crash.c

@@ -24,6 +24,7 @@ int kdump_status[NR_CPUS];
 static atomic_t kdump_cpu_frozen;
 atomic_t kdump_in_progress;
 static int kdump_on_init = 1;
+static int kdump_on_fatal_mca = 1;
 
 static inline Elf64_Word
 *append_elf_note(Elf64_Word *buf, char *name, unsigned type, void *data,
@@ -148,7 +149,7 @@ kdump_init_notifier(struct notifier_block *self, unsigned long val, void *data)
 	struct ia64_mca_notify_die *nd;
 	struct die_args *args = data;
 
-	if (!kdump_on_init)
+	if (!kdump_on_init && !kdump_on_fatal_mca)
 		return NOTIFY_DONE;
 
 	if (!ia64_kimage) {
@@ -174,11 +175,14 @@ kdump_init_notifier(struct notifier_block *self, unsigned long val, void *data)
 
 	switch (val) {
 		case DIE_INIT_MONARCH_PROCESS:
-			atomic_set(&kdump_in_progress, 1);
-			*(nd->monarch_cpu) = -1;
+			if (kdump_on_init) {
+				atomic_set(&kdump_in_progress, 1);
+				*(nd->monarch_cpu) = -1;
+			}
 			break;
 		case DIE_INIT_MONARCH_LEAVE:
-			machine_kdump_on_init();
+			if (kdump_on_init)
+				machine_kdump_on_init();
 			break;
 		case DIE_INIT_SLAVE_LEAVE:
 			if (atomic_read(&kdump_in_progress))
@@ -189,16 +193,19 @@ kdump_init_notifier(struct notifier_block *self, unsigned long val, void *data)
 				unw_init_running(kdump_cpu_freeze, NULL);
 			break;
 		case DIE_MCA_MONARCH_LEAVE:
-		     /* die_register->signr indicate if MCA is recoverable */
-			if (!args->signr)
+			/* die_register->signr indicate if MCA is recoverable */
+			if (kdump_on_fatal_mca && !args->signr) {
+				atomic_set(&kdump_in_progress, 1);
+				*(nd->monarch_cpu) = -1;
 				machine_kdump_on_init();
+			}
 			break;
 	}
 	return NOTIFY_DONE;
 }
 
 #ifdef CONFIG_SYSCTL
-static ctl_table kdump_on_init_table[] = {
+static ctl_table kdump_ctl_table[] = {
 	{
 		.ctl_name = CTL_UNNUMBERED,
 		.procname = "kdump_on_init",
@@ -207,6 +214,14 @@ static ctl_table kdump_on_init_table[] = {
 		.mode = 0644,
 		.proc_handler = &proc_dointvec,
 	},
+	{
+		.ctl_name = CTL_UNNUMBERED,
+		.procname = "kdump_on_fatal_mca",
+		.data = &kdump_on_fatal_mca,
+		.maxlen = sizeof(int),
+		.mode = 0644,
+		.proc_handler = &proc_dointvec,
+	},
 	{ .ctl_name = 0 }
 };
 
@@ -215,7 +230,7 @@ static ctl_table sys_table[] = {
 	  .ctl_name = CTL_KERN,
 	  .procname = "kernel",
 	  .mode = 0555,
-	  .child = kdump_on_init_table,
+	  .child = kdump_ctl_table,
 	},
 	{ .ctl_name = 0 }
 };

arch/ia64/kernel/mca.c

@@ -1266,16 +1266,12 @@ ia64_mca_handler(struct pt_regs *regs, struct switch_stack *sw,
 	} else {
 		/* Dump buffered message to console */
 		ia64_mlogbuf_finish(1);
-#ifdef CONFIG_KEXEC
-		atomic_set(&kdump_in_progress, 1);
-		monarch_cpu = -1;
-#endif
 	}
+
 	if (notify_die(DIE_MCA_MONARCH_LEAVE, "MCA", regs, (long)&nd, 0, recover)
 			== NOTIFY_STOP)
 		ia64_mca_spin(__func__);
 
-
 	if (atomic_dec_return(&mca_count) > 0) {
 		int i;