nvmet: handle keep-alive timer when kato is modified by a set features cmd

A user may modify the kato by a set features cmd.  To properly deal
with races or a kato value of 0 (no keep alive enabled) change
nvmet_set_feat_kato to first disable the timer, then set the value
and then re-enable the timer.
Signed-off-by: Amit Engel <amit.engel@dell.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/target/admin-cmd.c

@@ -727,7 +727,9 @@ u16 nvmet_set_feat_kato(struct nvmet_req *req)
 {
 	u32 val32 = le32_to_cpu(req->cmd->common.cdw11);
 
+	nvmet_stop_keep_alive_timer(req->sq->ctrl);
 	req->sq->ctrl->kato = DIV_ROUND_UP(val32, 1000);
+	nvmet_start_keep_alive_timer(req->sq->ctrl);
 
 	nvmet_set_result(req, req->sq->ctrl->kato);
 

drivers/nvme/target/core.c

@@ -395,7 +395,7 @@ static void nvmet_keep_alive_timer(struct work_struct *work)
 	nvmet_ctrl_fatal_error(ctrl);
 }
 
-static void nvmet_start_keep_alive_timer(struct nvmet_ctrl *ctrl)
+void nvmet_start_keep_alive_timer(struct nvmet_ctrl *ctrl)
 {
 	if (unlikely(ctrl->kato == 0))
 		return;
@@ -407,7 +407,7 @@ static void nvmet_start_keep_alive_timer(struct nvmet_ctrl *ctrl)
 	schedule_delayed_work(&ctrl->ka_work, ctrl->kato * HZ);
 }
 
-static void nvmet_stop_keep_alive_timer(struct nvmet_ctrl *ctrl)
+void nvmet_stop_keep_alive_timer(struct nvmet_ctrl *ctrl)
 {
 	if (unlikely(ctrl->kato == 0))
 		return;

drivers/nvme/target/nvmet.h

@@ -395,6 +395,8 @@ void nvmet_get_feat_async_event(struct nvmet_req *req);
 u16 nvmet_set_feat_kato(struct nvmet_req *req);
 u16 nvmet_set_feat_async_event(struct nvmet_req *req, u32 mask);
 void nvmet_execute_async_event(struct nvmet_req *req);
+void nvmet_start_keep_alive_timer(struct nvmet_ctrl *ctrl);
+void nvmet_stop_keep_alive_timer(struct nvmet_ctrl *ctrl);
 
 u16 nvmet_parse_connect_cmd(struct nvmet_req *req);
 void nvmet_bdev_set_limits(struct block_device *bdev, struct nvme_id_ns *id);