Re: [PATCH v4 2/6] nbd: convert to use blk_mq_find_and_get_req()

[Ming Lei]

On Wed, Sep 08, 2021 at 03:37:06PM +0800, yukuai (C) wrote:
> On 2021/09/08 15:30, Ming Lei wrote:
> 
> > > +put_req:
> > > +	if (req)
> > > +		blk_mq_put_rq_ref(req);
> > >   	return ret ? ERR_PTR(ret) : cmd;
> > 
> > After the request's refcnt is dropped, it can be freed immediately, then
> > one stale command is returned to caller.
> 
> Hi, Ming
> 
> It's right this patch leave this problem. Please take a look at patch 3
> and patch 4, the problem should be fixed with these patches.

Not see it is addressed in patch 3 & 4, and it is one obvious fault in
patch 2, please fix it from beginning by moving the refcnt drop
into recv_work().

BTW, the approach in patch 3 looks fine, which is very similar with
SCSI's handling.

Thanks,
Ming