Re: [PATCH] sched: provide scheduler_ipi() callback in response to smp_send_reschedule()

On Wed, 2011-02-09 at 17:14 +1100, Benjamin Herrenschmidt wrote:

On Mon, 2011-02-07 at 14:54 +0100, Peter Zijlstra wrote:

quoted

On Mon, 2011-02-07 at 10:26 +1100, Benjamin Herrenschmidt wrote:

quoted

You missed:

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 9813605..467d122 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c

@@ -98,6 +98,7 @@ void smp_message_recv(int msg)
                break;
        case PPC_MSG_RESCHEDULE:
                /* we notice need_resched on exit */
+               scheduler_ipi();
                break;
        case PPC_MSG_CALL_FUNC_SINGLE:
                generic_smp_call_function_single_interrupt();

Fold that in and add:

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Thanks Ben!

BTW. I we lurking at some of our CPU hotplug code and I think I cannot
totally guarantee that this won't be called on an offline CPU. If that's
a problem, you may want to add a test for that.

IE. The call function IPIs are normally not going to be sent to an
offlined CPU, and stop_machine should be a good enough fence here, but
we do abuse reschedule for a number of things (including in some case
to wake up a sleeping CPU that was pseudo-offlined :-)

Hmm, I _think_ that should all work out nicely, but we'll see, if when
this stuff hits the tree powerpc machines start falling over we'd better
put that check in ;-)

Meanwhile I'm going to preserve this comment in the changelog of this
patch so we don't forget.