[PATCH 6.1.y 1/2] nvme-tcp: fix potential unbalanced freeze & unfreeze

[PATCH 6.1.y 1/2] nvme-tcp: fix potential unbalanced freeze & unfreeze

[Sagi Grimberg]

From: Ming Lei <ming.lei@redhat.com>

Move start_freeze into nvme_tcp_configure_io_queues(), and there is
at least two benefits:

1) fix unbalanced freeze and unfreeze, since re-connection work may
fail or be broken by removal

2) IO during error recovery can be failfast quickly because nvme fabrics
unquiesces queues after teardown.

One side-effect is that !mpath request may timeout during connecting
because of queue topo change, but that looks not one big deal:

1) same problem exists with current code base

2) compared with !mpath, mpath use case is dominant

Fixes: 2875b0aecabe ("nvme-tcp: fix controller reset hang during traffic")
Cc: stable@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/nvme/host/tcp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 1dc7c733c7e3..8d67cdd844f5 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1884,6 +1884,7 @@ static int nvme_tcp_configure_io_queues(struct nvme_ctrl *ctrl, bool new)
 		goto out_cleanup_connect_q;
 
 	if (!new) {
+		nvme_start_freeze(ctrl);
 		nvme_start_queues(ctrl);
 		if (!nvme_wait_freeze_timeout(ctrl, NVME_IO_TIMEOUT)) {
 			/*
@@ -1892,6 +1893,7 @@ static int nvme_tcp_configure_io_queues(struct nvme_ctrl *ctrl, bool new)
 			 * to be safe.
 			 */
 			ret = -ENODEV;
+			nvme_unfreeze(ctrl);
 			goto out_wait_freeze_timed_out;
 		}
 		blk_mq_update_nr_hw_queues(ctrl->tagset,
@@ -1996,7 +1998,6 @@ static void nvme_tcp_teardown_io_queues(struct nvme_ctrl *ctrl,
 	if (ctrl->queue_count <= 1)
 		return;
 	nvme_stop_admin_queue(ctrl);
-	nvme_start_freeze(ctrl);
 	nvme_stop_queues(ctrl);
 	nvme_sync_io_queues(ctrl);
 	nvme_tcp_stop_io_queues(ctrl);
-- 
2.41.0

[PATCH 6.1.y 2/2] nvme-rdma: fix potential unbalanced freeze & unfreeze

[Sagi Grimberg]

From: Ming Lei <ming.lei@redhat.com>

Move start_freeze into nvme_rdma_configure_io_queues(), and there is
at least two benefits:

1) fix unbalanced freeze and unfreeze, since re-connection work may
fail or be broken by removal

2) IO during error recovery can be failfast quickly because nvme fabrics
unquiesces queues after teardown.

One side-effect is that !mpath request may timeout during connecting
because of queue topo change, but that looks not one big deal:

1) same problem exists with current code base

2) compared with !mpath, mpath use case is dominant

Fixes: 9f98772ba307 ("nvme-rdma: fix controller reset hang during traffic")
Cc: stable@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/nvme/host/rdma.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 80383213b882..c478480f54aa 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -923,6 +923,7 @@ static int nvme_rdma_configure_io_queues(struct nvme_rdma_ctrl *ctrl, bool new)
 		goto out_cleanup_tagset;
 
 	if (!new) {
+		nvme_start_freeze(&ctrl->ctrl);
 		nvme_start_queues(&ctrl->ctrl);
 		if (!nvme_wait_freeze_timeout(&ctrl->ctrl, NVME_IO_TIMEOUT)) {
 			/*
@@ -931,6 +932,7 @@ static int nvme_rdma_configure_io_queues(struct nvme_rdma_ctrl *ctrl, bool new)
 			 * to be safe.
 			 */
 			ret = -ENODEV;
+			nvme_unfreeze(&ctrl->ctrl);
 			goto out_wait_freeze_timed_out;
 		}
 		blk_mq_update_nr_hw_queues(ctrl->ctrl.tagset,
@@ -980,7 +982,6 @@ static void nvme_rdma_teardown_io_queues(struct nvme_rdma_ctrl *ctrl,
 		bool remove)
 {
 	if (ctrl->ctrl.queue_count > 1) {
-		nvme_start_freeze(&ctrl->ctrl);
 		nvme_stop_queues(&ctrl->ctrl);
 		nvme_sync_io_queues(&ctrl->ctrl);
 		nvme_rdma_stop_io_queues(ctrl);
-- 
2.41.0

Re: [PATCH 6.1.y 1/2] nvme-tcp: fix potential unbalanced freeze & unfreeze

[Greg KH]

On Sun, Aug 13, 2023 at 05:44:59PM +0300, Sagi Grimberg wrote:
> From: Ming Lei <ming.lei@redhat.com>
> 
> Move start_freeze into nvme_tcp_configure_io_queues(), and there is
> at least two benefits:
> 
> 1) fix unbalanced freeze and unfreeze, since re-connection work may
> fail or be broken by removal
> 
> 2) IO during error recovery can be failfast quickly because nvme fabrics
> unquiesces queues after teardown.
> 
> One side-effect is that !mpath request may timeout during connecting
> because of queue topo change, but that looks not one big deal:
> 
> 1) same problem exists with current code base
> 
> 2) compared with !mpath, mpath use case is dominant
> 
> Fixes: 2875b0aecabe ("nvme-tcp: fix controller reset hang during traffic")
> Cc: stable@vger.kernel.org
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> Tested-by: Yi Zhang <yi.zhang@redhat.com>
> Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
>  drivers/nvme/host/tcp.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Next time, can you give us a hint as to what the upstream commit is for
this and the other patches you sent?  I'll dig it out for now, but it
makes it much easier if I don't have to do that :)

thanks,

greg k-h