linux-kernel - Re: [PATCH v4 8/8] nvme-rdma: Unfreeze queues on reconnect

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Date:   Mon, 9 Aug 2021 10:58:07 +0200
From:   Daniel Wagner <dwagner@...e.de>
To:     Sagi Grimberg <sagi@...mberg.me>
Cc:     linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
        James Smart <james.smart@...adcom.com>,
        Keith Busch <kbusch@...nel.org>,
        Ming Lei <ming.lei@...hat.com>, Hannes Reinecke <hare@...e.de>,
        Wen Xiong <wenxiong@...ibm.com>
Subject: Re: [PATCH v4 8/8] nvme-rdma: Unfreeze queues on reconnect

Hi Sagi,

On Fri, Aug 06, 2021 at 12:59:15PM -0700, Sagi Grimberg wrote:
> 
> > During the queue teardown in nvme_rdma_teardown_io_queues() freeze is
> > called unconditionally. When we reconnect we need to pair the freeze
> > with an unfreeze to avoid hanging I/Os. For newly created connection
> > this is not needed.
> > 
> > Fixes: 9f98772ba307 ("nvme-rdma: fix controller reset hang during traffic")
> > Signed-off-by: Daniel Wagner <dwagner@...e.de>
> > ---
> >   drivers/nvme/host/rdma.c | 2 ++
> >   1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
> > index de2a8950d282..21a8a5353af0 100644
> > --- a/drivers/nvme/host/rdma.c
> > +++ b/drivers/nvme/host/rdma.c
> > @@ -901,6 +901,8 @@ static int nvme_rdma_configure_admin_queue(struct nvme_rdma_ctrl *ctrl,
> >   			error = PTR_ERR(ctrl->ctrl.admin_q);
> >   			goto out_cleanup_fabrics_q;
> >   		}
> > +	} else {
> > +		nvme_unfreeze(&ctrl->ctrl);
> 
> That seems misplaced.. unfreezing the I/O queues when setting up the admin
> queue?

Indeed. After looking again on it, this should be almost identically to
the tcp.c fix in nvme_rdma_configure_io_queues.

BTW, I am working on getting a RDMA test setup running. Hopefully I have
all the right licenses on the array.

Daniel