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    SubjectRe: [PATCH tip/core/rcu 7/9] arm64: Use common outgoing-CPU-notification code
    Hi Paul,

    Sorry for being late on this one.

    On Tue, May 12, 2015 at 10:50:05PM +0100, Paul E. McKenney wrote:
    > From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
    >
    > This commit removes the open-coded CPU-offline notification with new
    > common code. In particular, this change avoids calling scheduler code
    > using RCU from an offline CPU that RCU is ignoring. This is a minimal
    > change. A more intrusive change might invoke the cpu_check_up_prepare()
    > and cpu_set_state_online() functions at CPU-online time, which would
    > allow onlining throw an error if the CPU did not go offline properly.
    >
    > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    > Cc: linux-arm-kernel@lists.infradead.org
    > Cc: Catalin Marinas <catalin.marinas@arm.com>
    > Cc: Will Deacon <will.deacon@arm.com>
    > ---
    > arch/arm64/kernel/smp.c | 6 ++----
    > 1 file changed, 2 insertions(+), 4 deletions(-)

    I don't have a better idea, so:

    Acked-by: Will Deacon <will.deacon@arm.com>

    Is this queued via -tip already, or can we pick it into the arm64 tree
    for 4.2?

    Cheers,

    Will

    > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
    > index 2cb008177252..a899c1beff54 100644
    > --- a/arch/arm64/kernel/smp.c
    > +++ b/arch/arm64/kernel/smp.c
    > @@ -253,15 +253,13 @@ static int op_cpu_kill(unsigned int cpu)
    > return cpu_ops[cpu]->cpu_kill(cpu);
    > }
    >
    > -static DECLARE_COMPLETION(cpu_died);
    > -
    > /*
    > * called on the thread which is asking for a CPU to be shutdown -
    > * waits until shutdown has completed, or it is timed out.
    > */
    > void __cpu_die(unsigned int cpu)
    > {
    > - if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
    > + if (!cpu_wait_death(cpu, 5)) {
    > pr_crit("CPU%u: cpu didn't die\n", cpu);
    > return;
    > }
    > @@ -294,7 +292,7 @@ void cpu_die(void)
    > local_irq_disable();
    >
    > /* Tell __cpu_die() that this CPU is now safe to dispose of */
    > - complete(&cpu_died);
    > + (void)cpu_report_death();
    >
    > /*
    > * Actually shutdown the CPU. This must never fail. The specific hotplug
    > --
    > 1.8.1.5
    >


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