sparc64: Add self-IPI support for smp_send_reschedule()

CONFIG_NO_HZ_FULL requires possibility of smp_send_reschedule()
for the calling CPU. Currently, it is used in inc_nr_running()
scheduler primitive only.

Nobody calls smp_send_reschedule() from preemptible context
(furthermore, it looks like it will be save if anybody use it
another way in the future). But anyway I add WARN_ON() here
just to return here if anything changes.
Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
CC: David Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/smp_64.c

@@ -1399,8 +1399,13 @@ void __init smp_cpus_done(unsigned int max_cpus)
 
 void smp_send_reschedule(int cpu)
 {
-	xcall_deliver((u64) &xcall_receive_signal, 0, 0,
-		      cpumask_of(cpu));
+	if (cpu == smp_processor_id()) {
+		WARN_ON_ONCE(preemptible());
+		set_softint(1 << PIL_SMP_RECEIVE_SIGNAL);
+	} else {
+		xcall_deliver((u64) &xcall_receive_signal,
+			      0, 0, cpumask_of(cpu));
+	}
 }
 
 void __irq_entry smp_receive_signal_client(int irq, struct pt_regs *regs)