sched: Provide scheduler_ipi() callback in response to smp_send_reschedule()

For future rework of try_to_wake_up() we'd like to push part of that
function onto the CPU the task is actually going to run on.

In order to do so we need a generic callback from the existing scheduler IPI.

This patch introduces such a generic callback: scheduler_ipi() and
implements it as a NOP.

BenH notes: PowerPC might use this IPI on offline CPUs under rare conditions!

Acked-by: Russell King <[email protected]>
Acked-by: Martin Schwidefsky <[email protected]>
Acked-by: Chris Metcalf <[email protected]>
Acked-by: Jesper Nilsson <[email protected]>
Acked-by: Benjamin Herrenschmidt <[email protected]>
Signed-off-by: Ralf Baechle <[email protected]>
Reviewed-by: Frank Rowand <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Nick Piggin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Andrew Morton <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]

1 files changed, 2 insertions, 3 deletions

diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 513deac7228d..013e7eba83bb 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -194,14 +194,13 @@ static void native_stop_other_cpus(int wait)
 }
 
 /*
- * Reschedule call back. Nothing to do,
- * all the work is done automatically when
- * we return from the interrupt.
+ * Reschedule call back.
  */
 void smp_reschedule_interrupt(struct pt_regs *regs)
 {
 	ack_APIC_irq();
 	inc_irq_stat(irq_resched_count);
+	scheduler_ipi();
 	/*
 	 * KVM uses this interrupt to force a cpu out of guest mode
 	 */