[PATCH] s390: cpu up retries

Retry starting of new cpu if sigp restart returns condition code 2 (busy).
Signed-off-by: Michael Ryan <ryan@funsoft.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/s390/kernel/smp.c

@@ -665,7 +665,9 @@ __cpu_up(unsigned int cpu)
         cpu_lowcore->current_task = (unsigned long) idle;
         cpu_lowcore->cpu_data.cpu_nr = cpu;
 	eieio();
-	signal_processor(cpu,sigp_restart);
+
+	while (signal_processor(cpu,sigp_restart) == sigp_busy)
+		udelay(10);
 
 	while (!cpu_online(cpu))
 		cpu_relax();