On Mon, Jun 17, 2019 at 12:58:19PM +0100, Mark Rutland wrote:
> On Tue, Jun 11, 2019 at 12:24:10PM -0700, Paul E. McKenney wrote:
> > 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 <paul...@linux.vnet.ibm.com>
> > Cc: linux-arm-ker...@lists.infradead.org
> > Cc: Russell King <li...@arm.linux.org.uk>
> > Cc: Mark Rutland <mark.rutl...@arm.com>
> > Tested-by: Dietmar Eggemann <dietmar.eggem...@arm.com>
>
> FWIW:
>
> Acked-by: Mark Rutland <mark.rutl...@arm.com>
>
> On the assumption that Russell is ok with this, I think this should be
> dropped into the ARM patch system [1].
>
> Paul, are you familiar with that, or would you prefer that someone else
> submits the patch there? I can do so if you'd like.
I never have used this system, so please do drop it in there! Let me
know when you have done so, and I will then drop it from -rcu.
Thanx, Paul
> Thanks,
> Mark.
>
> [1] https://www.armlinux.org.uk/developer/patches/info.php
>
> >
> > diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
> > index ebc53804d57b..8687d619260f 100644
> > --- a/arch/arm/kernel/smp.c
> > +++ b/arch/arm/kernel/smp.c
> > @@ -267,15 +267,13 @@ int __cpu_disable(void)
> > return 0;
> > }
> >
> > -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_err("CPU%u: cpu didn't die\n", cpu);
> > return;
> > }
> > @@ -322,7 +320,7 @@ void arch_cpu_idle_dead(void)
> > * this returns, power and/or clocks can be removed at any point
> > * from this CPU and its cache by platform_cpu_kill().
> > */
> > - complete(&cpu_died);
> > + (void)cpu_report_death();
> >
> > /*
> > * Ensure that the cache lines associated with that completion are
> >
>
