Re: [PATCH v3] nullb: Prevent use of legacy request queue mode

[Jens Axboe <axboe@kernel.dk>]

On 2/11/19 4:47 PM, Damien Le Moal wrote:
> When null_blk queue mode is specified together with modprobe/insmod, a
> check to prevent setting the nullb device queue mode to 1 (NULL_Q_RQ) is
> done. However, the same check is not performed when setting up a nullb
> device through configfs, resulting in a oops (NULL pointer dereference
> for the device request queue).
> 
> Fix this problem by checking for an invalid queue mode value in
> null_validate_conf(), propagating -EINVAL to null_add_dev() if the queue
> mode is NULL_Q_RQ. While at it, also fix the propagation to user space
> of null_add_dev() return value when a nullb device is created through
> the power attribute of configfs.
> 
> Finally, remove the "1=rq" value from the list of possible values of
> the queue_mode module argument to make it clear that this is no longer
> a valid setting.

I actually left that in there on purpose, to avoid breaking test
scripts. It's not the perfect solution, but I viewed it as the
lesser of two evils. Maybe we're fine now, I think blktests has
been fixed a while back?

-- 
Jens Axboe