Re: [PATCH] stopmachine: add stopmachine_timeout v4

[Max Krasnyansky]

Hidetoshi Seto wrote:
> If stop_machine() invoked while one of onlined cpu is locked up
> by some reason, stop_machine cannot finish its work because the
> locked cpu cannot stop.  This means all other healthy cpus
> will be blocked infinitely by one dead cpu.
> 
> This patch allows stop_machine to return -EBUSY with some printk
> messages if any of stop_machine's threads cannot start running on
> its target cpu in time.  You can enable this timeout via sysctl.
> 
> v4:
>  - move extern into linux/stop_machine.h and add include of the
>    header to kernel/sysctl.c.  Now stopmachine_timeout is available
>    only on smp.
> 
> v3:
>  - set stopmachine_timeout default to 0 (= never timeout)
> 
> v2:
>  - remove fix for warning since it will be fixed upcoming typesafe
>    patches
>  - make stopmachine_timeout from secs to msecs
>  - allow disabling timeout by setting the stopmachine_timeout to 0
> 
> Signed-off-by: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx>
> ---
>  include/linux/stop_machine.h |    3 ++
>  kernel/stop_machine.c        |   54 +++++++++++++++++++++++++++++++++++++++--
>  kernel/sysctl.c              |   12 +++++++++
>  3 files changed, 66 insertions(+), 3 deletions(-)

Looks good to me.
Ack.

Max
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