x86: provide __smp_call_function

This function is used in smp_send_stop(). It's like
smp_call_function_mask, but always go to all online cpus,
and does not take any locks.

It is added to x86_64, but will soon be unified in a common file
Signed-off-by: NGlauber Costa <gcosta@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/smp_64.c

@@ -322,6 +322,38 @@ void unlock_ipi_call_lock(void)
 	spin_unlock_irq(&call_lock);
 }
 
+static void __smp_call_function(void (*func) (void *info), void *info,
+				int nonatomic, int wait)
+{
+	struct call_data_struct data;
+	int cpus = num_online_cpus() - 1;
+
+	if (!cpus)
+		return;
+
+	data.func = func;
+	data.info = info;
+	atomic_set(&data.started, 0);
+	data.wait = wait;
+	if (wait)
+		atomic_set(&data.finished, 0);
+
+	call_data = &data;
+	mb();
+
+	/* Send a message to all other CPUs and wait for them to respond */
+	send_IPI_allbutself(CALL_FUNCTION_VECTOR);
+
+	/* Wait for response */
+	while (atomic_read(&data.started) != cpus)
+		cpu_relax();
+
+	if (wait)
+		while (atomic_read(&data.finished) != cpus)
+			cpu_relax();
+}
+
+
 /*
  * this function sends a 'generic call function' IPI to all other CPU
  * of the system defined in the mask.
@@ -424,7 +456,7 @@ void smp_send_stop(void)
 	/* Don't deadlock on the call lock in panic */
 	nolock = !spin_trylock(&call_lock);
 	local_irq_save(flags);
-	__smp_call_function_mask(cpu_online_map, stop_this_cpu, NULL, 0);
+	__smp_call_function(stop_this_cpu, NULL, 0, 0);
 	if (!nolock)
 		spin_unlock(&call_lock);
 	disable_local_APIC();