Messages in this thread Patch in this message | | | Date | Mon, 20 May 2013 15:20:33 +0530 | From | "Srivatsa S. Bhat" <> | Subject | Re: [RFC PATCH nohz] return NOTIFY_BAD in cpu down call back to stop offlining the cpu |
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On 05/17/2013 02:14 PM, Li Zhong wrote: > In tick_nohz_cpu_down_callback() if the cpu is the one handling > timekeeping , it seems that we should return something that could stop > notify CPU_DOWN_PREPARE, and then start notify CPU_DOWN_FAILED on the > already called notifier call backs. > > -EINVAL will be converted to 0 by notifier_to_errno(),
This above line is not relevant here, because notifier_call_chain() doesn't use notifier_to/from_errno(). It simply uses a straight-forward check like this:
if ((ret & NOTIFY_STOP_MASK) == NOTIFY_STOP_MASK) break;
> then the cpu > would be taken down with part of the DOWN_PREPARE notifier callbacks > called, and something bad could happen after that. > > Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com> > ---
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> kernel/time/tick-sched.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index bc67d42..17b8155 100644 > --- a/kernel/time/tick-sched.c > +++ b/kernel/time/tick-sched.c > @@ -306,7 +306,7 @@ static int __cpuinit tick_nohz_cpu_down_callback(struct notifier_block *nfb, > * we can't safely shutdown that CPU. > */ > if (have_nohz_full_mask && tick_do_timer_cpu == cpu) > - return -EINVAL; > + return NOTIFY_BAD; > break; > } > return NOTIFY_OK; > Regards, Srivatsa S. Bhat
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