On Tue, 2016-09-27 at 09:43 -0700, Bart Van Assche wrote:
> On 09/27/2016 09:31 AM, Steve Wise wrote:
> > > @@ -2079,11 +2075,15 @@ EXPORT_SYMBOL_GPL(nvme_kill_queues);
> > > void nvme_stop_queues(struct nvme_ctrl *ctrl)
> > > {
> > > struct nvme_ns *ns;
> > > + struct request_queue *q;
> > >
> > > mutex_lock(&ctrl->namespaces_mutex);
> > > list_for_each_entry(ns, &ctrl->namespaces, list) {
> > > - blk_mq_cancel_requeue_work(ns->queue);
> > > - blk_mq_stop_hw_queues(ns->queue);
> > > + q = ns->queue;
> > > + blk_quiesce_queue(q);
> > > + blk_mq_cancel_requeue_work(q);
> > > + blk_mq_stop_hw_queues(q);
> > > + blk_resume_queue(q);
> > > }
> > > mutex_unlock(&ctrl->namespaces_mutex);
> >
> > Hey Bart, should nvme_stop_queues() really be resuming the blk
> > queue?
>
> Hello Steve,
>
> Would you perhaps prefer that blk_resume_queue(q) is called from
> nvme_start_queues()? I think that would make the NVMe code harder to
> review. The above code won't cause any unexpected side effects if an
> NVMe namespace is removed after nvme_stop_queues() has been called
> and before nvme_start_queues() is called. Moving the
> blk_resume_queue(q) call into nvme_start_queues() will only work as
> expected if no namespaces are added nor removed between the
> nvme_stop_queues() and nvme_start_queues() calls. I'm not familiar
> enough with the NVMe code to know whether or not this change is safe
> ...
It's something that looks obviously wrong, so explain why you need to
do it, preferably in a comment above the function.
James
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