[PATCHv2 14/17] nvme: fix Clang context analysis warning in rdma.c

[Nilay Shroff]

After adding Clang lock context annotations in rdma.c, Clang reports
the following warning when context analysis is enabled:

drivers/nvme/host/rdma.c:972:24: warning: passing pointer to variable 'list' requires holding mutex 'nvme_rdma_ctrl_mutex'
	  [-Wthread-safety-pointer]
  972 |         if (list_empty(&ctrl->list))
	  |                               ^

The warning is triggered because ctrl->list is annotated as being
protected by nvme_rdma_ctrl_mutex, but list_empty(&ctrl->list) is
invoked without holding that mutex.

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

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

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 2c55f05f7550..da7770025059 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -969,10 +969,11 @@ static void nvme_rdma_free_ctrl(struct nvme_ctrl *nctrl)
 {
 	struct nvme_rdma_ctrl *ctrl = to_rdma_ctrl(nctrl);
 
-	if (list_empty(&ctrl->list))
-		goto free_ctrl;
-
 	mutex_lock(&nvme_rdma_ctrl_mutex);
+	if (list_empty(&ctrl->list)) {
+		mutex_unlock(&nvme_rdma_ctrl_mutex);
+		goto free_ctrl;
+	}
 	list_del(&ctrl->list);
 	mutex_unlock(&nvme_rdma_ctrl_mutex);
 
-- 
2.53.0