Unexpected issues with 2 NVME initiators using the same target

[Sagi Grimberg]

> I still get the local protection errors with this patch. I am seeing a
> ping timeout on the initiator when I reboot the target.
> [Tue Jun 20 16:41:21 2017]  connection7:0: detected conn error (1011)
> [Tue Jun 20 16:41:26 2017]  session7: session recovery timed out after 5 secs
> 

Not a big surprise as its not really addressing the issue...

> Since I'm gracefully shutting down the targets in this case, shouldn't
> the connection be closed gracefully by the target instead of the
> initiator having to wait for ping to fail?

Not really, even in orderly shutdown, the device driver (mlx5 in
this case) shutdown sequence is triggered before ib_isert and
fires DEVICE_REMOVAL events to all its upper layer users (ib_isert
being one of them), which forces resource teardown (no disconnect).

We could resgister a shutdown handler in ib_isert, but its not really
its responsibility as a transport driver..

It would be nice if we had targetcli daemon'ised as a service
and register a shutdown notification, orderly remove and save the
existing configuration before the kernel even sees it. But its
a different scope really...

CC'ing target-devel