[PATCHv2 16/17] nvme: fix Clang context analysis warning in tcp.c

[Nilay Shroff]

After adding Clang context annotations, compiling tcp.c reports the
following warning while context analysis is enabled:

drivers/nvme/host/tcp.c:2572:24: warning: passing pointer to variable 'list' requires holding mutex 'nvme_tcp_ctrl_mutex'
	  [-Wthread-safety-pointer]
2572 |         if (list_empty(&ctrl->list))
     |                               ^

The above warning is triggered because ctrl->list is guarded with mutex
nvme_tcp_ctrl_mutex but when list_empty(&ctrl->list) is invoked it
doesn't acquire nvme_tcp_ctrl_mutex.

Fix the warning by performing the list_empty(&ctrl->list) check while
holding nvme_tcp_ctrl_mutex.

Signed-off-by: Nilay Shroff <nilay at linux.ibm.com>
---
 drivers/nvme/host/tcp.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index c4662ccb5c49..86ef98aefeb4 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -2569,10 +2569,11 @@ static void nvme_tcp_free_ctrl(struct nvme_ctrl *nctrl)
 {
 	struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
 
-	if (list_empty(&ctrl->list))
-		goto free_ctrl;
-
 	mutex_lock(&nvme_tcp_ctrl_mutex);
+	if (list_empty(&ctrl->list)) {
+		mutex_unlock(&nvme_tcp_ctrl_mutex);
+		goto free_ctrl;
+	}
 	list_del(&ctrl->list);
 	mutex_unlock(&nvme_tcp_ctrl_mutex);
 
-- 
2.53.0