On 11/16/21 3:18 AM, Keith Busch wrote:

On Tue, Nov 16, 2021 at 01:40:04AM +0000, Chaitanya Kulkarni wrote:

quoted

On 11/11/2021 2:59 AM, Hannes Reinecke wrote:

quoted

When opening a controller device node we should honour the O_NONBLOCK
flag to allow the device to be openend even if it's in state 'resetting'
or 'connecting'. This allows user-space applications to use a call to 'open'
to figure out if the controller is present, even if it's currently
undergoing a reset.

Signed-off-by: Hannes Reinecke <hare@suse.de>

Will resetting and connecting ever result is deleting the controller due
to error cases present in that path ?

If yes then application will have handle for something that might
go away in the future, should allow such a semantic ?

Resets can happen at any time, so they already have to handle it even if the
controller was live when they opened it. Perhaps the open should succeed for
any non-terminal state.

Indeed. And we should add a state check for the ioctl itself, returning 
an error when the device is not running.

I'll be sending an updated patchset.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer