Re: [PATCH] nvmet: fix false keep-alive timeout when a controller is torn down

Controller teardown flow may take some time in case it has many I/O
queues, and the host may not send us keep-alive during this period.
Hence reset the traffic based keep-alive timer so we don't trigger
a controller teardown as a result of a keep-alive expiration.

Reported-by: Yi Zhang <redacted>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
---
 drivers/nvme/target/core.c  | 16 ++++++++++++----
 drivers/nvme/target/nvmet.h |  2 +-
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 1853db38b682..e991b4671aeb 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c

@@ -388,10 +388,10 @@ static void nvmet_keep_alive_timer(struct work_struct *work)
 {
        struct nvmet_ctrl *ctrl = container_of(to_delayed_work(work),
                        struct nvmet_ctrl, ka_work);
-       bool cmd_seen = ctrl->cmd_seen;
+       bool reset_tbkas = ctrl->reset_tbkas;

-       ctrl->cmd_seen = false;
-       if (cmd_seen) {
+       ctrl->reset_tbkas = false;
+       if (reset_tbkas) {
                pr_debug("ctrl %d reschedule traffic based keep-alive timer\n",
                        ctrl->cntlid);
                schedule_delayed_work(&ctrl->ka_work, ctrl->kato * HZ);

@@ -804,6 +804,14 @@ void nvmet_sq_destroy(struct nvmet_sq *sq)
        percpu_ref_exit(&sq->ref);

        if (ctrl) {
+               /*
+                * teardown flow may take some time, and the host
+                * may not send us keep-alive during this period,
+                * hence reset the traffic based keep-alive timer
+                * so we don't trigger a controller teardown as
+                * a result of a keep-alive expiration.
+                */
+               ctrl->reset_tbkas = true;
                nvmet_ctrl_put(ctrl);
                sq->ctrl = NULL; /* allows reusing the queue later */
        }

@@ -952,7 +960,7 @@ bool nvmet_req_init(struct nvmet_req *req, struct nvmet_cq *cq,
        }

        if (sq->ctrl)
-               sq->ctrl->cmd_seen = true;
+               sq->ctrl->reset_tbkas = true;

        return true;

diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index d69a409515d6..53aea9a8056e 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h

@@ -167,7 +167,7 @@ struct nvmet_ctrl {
        struct nvmet_subsys     *subsys;
        struct nvmet_sq         **sqs;

-       bool                    cmd_seen;
+       bool                    reset_tbkas;

        struct mutex            lock;
        u64                     cap;
--

2.27.0


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