[PATCH] nvmet: Set ctrl->kato to a default NVMET_DISC_KATO value

[Christoph Hellwig]

On Mon, Sep 14, 2020 at 04:53:47PM -0700, Sagi Grimberg wrote:
>
>> Hi Sagi,
>> Still dealing with keep-alive timeout  zero value and how it affects other scenarios:
>> With my latest patch, when keep alive timeout is set to zero the keep-alive timer is disabled. (Upstream commit 0d3b6a8d213a30387b5104b2fb25376d18636f23)
>> But that’s only part of the picture,
>> What happens if a user starts with kato > 0 and modifying it by set feature a while after?
>> After modifying the kato to 0 with a set features we will never stop the timer
>> In a similar way, when starting with kato 0 and then modify to kato > 0 we will never start the timer
>>
>> We thought about solve it by adding checks in ‘nvmet_set_feat_kato’ for the above cases
>> And handle the ka_work accordingly
>> What do you think ?
>
> We can probably just cancel and restart the keep alive timer in that
> case..

Yes, the Set Features handler should:

 (1) cancel the timer
 (2) update it to the new value
 (3) start the timer again (nvmet_start_keep_alive_timer will handle
     the kato == 0 case)