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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, zhenwei pi <pizhenwei@bytedance.com>,
        Christoph Hellwig <hch@lst.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 319/408] nvmet: fix uninitialized work for zero kato
Date:   Tue, 27 Oct 2020 14:54:17 +0100
Message-Id: <20201027135509.835925964@linuxfoundation.org>
In-Reply-To: <20201027135455.027547757@linuxfoundation.org>
References: <20201027135455.027547757@linuxfoundation.org>
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From: zhenwei pi <pizhenwei@bytedance.com>

[ Upstream commit 85bd23f3dc09a2ae9e56885420e52c54bf983713 ]

When connecting a controller with a zero kato value using the following
command line

   nvme connect -t tcp -n NQN -a ADDR -s PORT --keep-alive-tmo=0

the warning below can be reproduced:

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 is caused by queuing up an uninitialized work.  Althrough the
keep-alive timer is disabled during allocating the controller (fixed in
0d3b6a8d213a), ka_work still has a chance to run (called by
nvmet_start_ctrl).

Fixes: 0d3b6a8d213a ("nvmet: Disable keep-alive timer when kato is cleared to 0h")
Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 7d7176369edf7..6b2f1e290fa73 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -1048,7 +1048,8 @@ 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)
-- 
2.25.1