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 <[email protected]>
> ---
Reviewed-by: Srivatsa S. Bhat <[email protected]>
> 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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