[PATCH] nvme: block ioctls if controller not in a live state

[James Smart]

On 5/14/2018 7:17 AM, Christoph Hellwig wrote:
> On Wed, May 09, 2018 at 09:29:13AM -0700, James Smart wrote:
>> That is the exact intent.  I do want the app to trigger off -EAGAIN in those
>> two states and try again after a delay./  Perhaps I should change from !LIVE
>> to NEW || RESETTING || CONNECTING to be more explicit.  I assumed !LIVE was
>> sufficient as the other states should transition to LIVE or the delete path
>> is taken which would remove the fd all together.
> The problem is that userspace reasonably expects to be able to call
> poll/select when used on a character device and it gets -EAGAIN.

What's stopping us from adding poll support to the dev node ?


>
> Maybe the right solution here is to just do a wait_event_interruptible to
> wait for the controller being live.

That's doable. I don't like hanging the app up for what could be 60s or 
so though (controller loss timeout).

--james