x86 kdump: make kdump_nmi_callback() a function ptr on crash_nmi_callback()

Impact: extend nmi_shootdown_cpus() with a callback

The reboot code will use a different function on crash_nmi_callback().
Adding a function pointer parameter to nmi_shootdown_cpus() for that.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/crash.c

@@ -29,10 +29,13 @@
 
 #include <mach_ipi.h>
 
+typedef void (*nmi_shootdown_cb)(int, struct die_args*);
+
 #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
 
 /* This keeps a track of which one is crashing cpu. */
 static int crashing_cpu;
+static nmi_shootdown_cb shootdown_callback;
 
 static atomic_t waiting_for_crash_ipi;
 
@@ -74,7 +77,7 @@ static int crash_nmi_callback(struct notifier_block *self,
 		return NOTIFY_STOP;
 	local_irq_disable();
 
-	kdump_nmi_callback(cpu, (struct die_args *)data);
+	shootdown_callback(cpu, (struct die_args *)data);
 
 	atomic_dec(&waiting_for_crash_ipi);
 	/* Assume hlt works */
@@ -97,13 +100,15 @@ static struct notifier_block crash_nmi_nb = {
 	.notifier_call = crash_nmi_callback,
 };
 
-static void nmi_shootdown_cpus(void)
+static void nmi_shootdown_cpus(nmi_shootdown_cb callback)
 {
 	unsigned long msecs;
 
 	/* Make a note of crashing cpu. Will be used in NMI callback.*/
 	crashing_cpu = safe_smp_processor_id();
 
+	shootdown_callback = callback;
+
 	atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
 	/* Would it be better to replace the trap vector here? */
 	if (register_die_notifier(&crash_nmi_nb))
@@ -126,7 +131,7 @@ static void nmi_shootdown_cpus(void)
 
 static void kdump_nmi_shootdown_cpus(void)
 {
-	nmi_shootdown_cpus();
+	nmi_shootdown_cpus(kdump_nmi_callback);
 
 	disable_local_APIC();
 }