ARM: fix rcu stalls on SMP platforms

commit 7deabca0 upstream.

We can stall RCU processing on SMP platforms if a CPU sits in its idle
loop for a long time.  This happens because we don't call irq_enter()
and irq_exit() around generic_smp_call_function_interrupt() and
friends.  Add the necessary calls, and remove the one from within
ipi_timer(), so that they're all in a common place.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
[add irq_enter()/irq_exit() in do_local_timer]
Signed-off-by: UCHINO Satoshi <satoshi.uchino@toshiba.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm/kernel/smp.c

@@ -445,9 +445,7 @@ static DEFINE_PER_CPU(struct clock_event_device, percpu_clockevent);
 static void ipi_timer(void)
 {
 	struct clock_event_device *evt = &__get_cpu_var(percpu_clockevent);
-	irq_enter();
 	evt->event_handler(evt);
-	irq_exit();
 }
 
 #ifdef CONFIG_LOCAL_TIMERS
@@ -458,7 +456,9 @@ asmlinkage void __exception_irq_entry do_local_timer(struct pt_regs *regs)
 
 	if (local_timer_ack()) {
 		__inc_irq_stat(cpu, local_timer_irqs);
+		irq_enter();
 		ipi_timer();
+		irq_exit();
 	}
 
 	set_irq_regs(old_regs);
@@ -568,7 +568,9 @@ asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 
 	switch (ipinr) {
 	case IPI_TIMER:
+		irq_enter();
 		ipi_timer();
+		irq_exit();
 		break;
 
 	case IPI_RESCHEDULE:
@@ -576,15 +578,21 @@ asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
 		break;
 
 	case IPI_CALL_FUNC:
+		irq_enter();
 		generic_smp_call_function_interrupt();
+		irq_exit();
 		break;
 
 	case IPI_CALL_FUNC_SINGLE:
+		irq_enter();
 		generic_smp_call_function_single_interrupt();
+		irq_exit();
 		break;
 
 	case IPI_CPU_STOP:
+		irq_enter();
 		ipi_cpu_stop(cpu);
+		irq_exit();
 		break;
 
 	default: