Re: [PATCH 2/2] nvme-pci: don't wait freeze during resetting

[Ming Lei <ming.lei@redhat.com>]

On Thu, Aug 25, 2022 at 06:05:30PM +0800, Chao Leng wrote:
> 
> 
> On 2022/8/21 16:47, Ming Lei wrote:
> > First it isn't necessary to call nvme_wait_freeze in nvme_reset_work().
> > If tagset isn't allocated, there can't be any inflight IOs; otherwise
> > blk_mq_update_nr_hw_queues can freeze & wait queues.
> > 
> > Second, since commit bdd6316094e0 ("block: Allow unfreezing of a queue
> > while requests are in progress"), it is fine to unfreeze queue without
> > draining inflight IOs.
> > 
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > ---
> >   drivers/nvme/host/pci.c | 1 -
> >   1 file changed, 1 deletion(-)
> > 
> > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> > index 3a1c37f32f30..91b2903fcc24 100644
> > --- a/drivers/nvme/host/pci.c
> > +++ b/drivers/nvme/host/pci.c
> > @@ -2910,7 +2910,6 @@ static void nvme_reset_work(struct work_struct *work)
> >   		nvme_free_tagset(dev);
> >   	} else {
> >   		nvme_start_queues(&dev->ctrl);
> > -		nvme_wait_freeze(&dev->ctrl);
> It is not safe.
> nvme_dev_add may call blk_mq_update_nr_hw_queues, blk_mq_update_nr_hw_queues
> require the state is frozen.

blk_mq_update_nr_hw_queues() calls blk_freeze_queue() for every queue in
this tagset, so it needn't nvme's freeze wait.


Thanks,
Ming