S390: Smp: remove call to ipi_call_lock()/ipi_call_unlock()

ipi_call_lock/unlock() lock resp. unlock call_function.lock. This lock
protects only the call_function data structure itself, but it's
completely unrelated to cpu_online_mask. The mask to which the IPIs
are sent is calculated before call_function.lock is taken in
smp_call_function_many(), so the locking around set_cpu_online() is
pointless and can be removed.

[ tglx: Massaged changelog ]

Signed-off-by: Yong Zhang <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Martin Schwidefsky <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Acked-by: Srivatsa S. Bhat <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>

arch/s390/kernel/smp.c

@@ -717,9 +717,7 @@ static void __cpuinit smp_start_secondary(void *cpuvoid)
 	init_cpu_vtimer();
 	pfault_init();
 	notify_cpu_starting(smp_processor_id());
-	ipi_call_lock();
 	set_cpu_online(smp_processor_id(), true);
-	ipi_call_unlock();
 	local_irq_enable();
 	/* cpu_idle will call schedule for us */
 	cpu_idle();