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    SubjectRe: [patch 08/34] arm: Use generic idle loop
    On Tue, Apr 30, 2013 at 05:49:06PM -0700, Stephen Boyd wrote:
    > On 04/25/13 14:01, Thomas Gleixner wrote:
    > > On Thu, 25 Apr 2013, Stephen Boyd wrote:
    > >> On 04/09/13 02:38, Russell King - ARM Linux wrote:
    > >>> On Tue, Apr 09, 2013 at 11:20:31AM +0200, Thomas Gleixner wrote:
    > >>>> On Mon, 8 Apr 2013, Russell King - ARM Linux wrote:
    > >>>>> On Mon, Mar 25, 2013 at 03:02:39PM +0100, Thomas Gleixner wrote:
    > >>>>> So, how can I review these changes when all there is is a git URL, and
    > >>>>> I *do* not want to pull them into my tree without first looking at the
    > >>>>> patches, possibly reviewing them and *replying* with the patch inline?
    > >>>> the patches were CC'ed to LKML and linux-arch and I expected that you
    > >>>> are at least having the latter. Find the relevant patch inlined below.
    > >>> I've not been on linux-arch for a few years now, after it evolved into
    > >>> yet another lkml-like list with high traffic rates, where mainly specific
    > >>> x86 issues seemed to be discussed, rather than it being a way to contact
    > >>> all arch maintainers.
    > >>>
    > >>>> It is a counter. I looked carefully at all the various slightly
    > >>>> differently fcked up implementations and picked the counter based one
    > >>>> as it fits all requirements.
    > >>> Great, thanks. The attached patch looks fine to me.
    > >> I'm pretty sure that we need to apply this patch now that
    > >> rcu_idle_enter()/exit() is called lower down in the idle loop. Kevin,
    > >> did you test hotplug?
    > > If the patch is agreed on, I guess I should take it via my idle
    > > consolidation branch, right ?
    >
    > Yes I think so. Hopefully Russell King or Paul McKenney can ack this patch.
    >
    > >
    > >> ----8<-----
    > >>
    > >> From: Stephen Boyd <sboyd@codeaurora.org>
    > >> Subject: [PATCH] ARM: smp: Drop RCU_NONIDLE usage in cpu_die()
    > >>
    > >> Before f7b861b (arm: Use generic idle loop, 2013-03-21) ARM would
    > >> kill the CPU within the rcu idle section. Now that the
    > >> rcu_idle_enter()/exit() pair have been pushed lower down in the
    > >> idle loop this is no longer true and so using RCU_NONIDLE here is
    > >> no longer necessary and also harmful because RCU is not actually
    > >> idle at this point.
    > >>
    > >> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

    From an RCU perspective:

    Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

    > >> ---
    > >> arch/arm/kernel/smp.c | 2 +-
    > >> 1 file changed, 1 insertion(+), 1 deletion(-)
    > >>
    > >> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
    > >> index 4619177..78f1eb5 100644
    > >> --- a/arch/arm/kernel/smp.c
    > >> +++ b/arch/arm/kernel/smp.c
    > >> @@ -233,7 +233,7 @@ void __ref cpu_die(void)
    > >> mb();
    > >>
    > >> /* Tell __cpu_die() that this CPU is now safe to dispose of */
    > >> - RCU_NONIDLE(complete(&cpu_died));
    > >> + complete(&cpu_died);
    > >>
    > >> /*
    > >> * actual CPU shutdown procedure is at least platform (if not
    > >>
    > >> --
    > >> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
    > >> hosted by The Linux Foundation
    > >>
    > >>
    >
    >
    > --
    > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
    > hosted by The Linux Foundation
    >



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