linux-kernel - [PATCH v2] nvmet: fix uninitialized work for zero kato

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Message-Id: <20201014033650.953656-1-pizhenwei@bytedance.com>
Date:   Wed, 14 Oct 2020 11:36:50 +0800
From:   zhenwei pi <pizhenwei@...edance.com>
To:     hch@....de, sagi@...mberg.me, chaitanya.kulkarni@....com
Cc:     linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
        pizhenwei@...edance.com
Subject: [PATCH v2] nvmet: fix uninitialized work for zero kato

Hit a warning:
WARNING: CPU: 1 PID: 241 at kernel/workqueue.c:1627 __queue_delayed_work+0x6d/0x90
with trace:
  mod_delayed_work_on+0x59/0x90
  nvmet_update_cc+0xee/0x100 [nvmet]
  nvmet_execute_prop_set+0x72/0x80 [nvmet]
  nvmet_tcp_try_recv_pdu+0x2f7/0x770 [nvmet_tcp]
  nvmet_tcp_io_work+0x63f/0xb2d [nvmet_tcp]
  ...

This could be reproduced easily with a keep alive time 0:
nvme connect -t tcp -n NQN -a ADDR -s PORT --keep-alive-tmo=0

Starting an uninitialized work when initiator connects with zero
kato. Althrough keep-alive timer is disabled during allocating a ctrl
(fix in 0d3b6a8d213a), ka_work still has a chance to run
(called by nvmet_start_ctrl).

Fixes:
Don't run keep alive work with zero kato.

Signed-off-by: zhenwei pi <pizhenwei@...edance.com>
---
 drivers/nvme/target/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index b7b63330b5ef..90e0c84df2af 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -1126,7 +1126,8 @@ static void nvmet_start_ctrl(struct nvmet_ctrl *ctrl)
 	 * in case a host died before it enabled the controller.  Hence, simply
 	 * reset the keep alive timer when the controller is enabled.
 	 */
-	mod_delayed_work(system_wq, &ctrl->ka_work, ctrl->kato * HZ);
+	if (ctrl->kato)
+		mod_delayed_work(system_wq, &ctrl->ka_work, ctrl->kato * HZ);
 }

 static void nvmet_clear_ctrl(struct nvmet_ctrl *ctrl)
-- 
2.11.0