[PATCH v2 2/2] nvme-tcp: avoid request double completion for concurrent nvme_tcp_timeout

[Chao Leng]

Each name space has a request queue, if complete request long time,
multi request queues may have time out requests at the same time,
nvme_tcp_timeout will execute concurrently. Multi requests in different
request queues may be queued in the same tcp queue, multi
nvme_tcp_timeout may call nvme_tcp_stop_queue at the same time.
The first nvme_tcp_stop_queue will clear NVME_TCP_Q_LIVE and continue
stopping the tcp queue(cancel io_work), but the others check
NVME_TCP_Q_LIVE is already cleared, and then directly complete the
requests, complete request before the io work is completely canceled may
lead to a use-after-free condition.
Add a multex lock to serialize nvme_tcp_stop_queue.

Signed-off-by: Chao Leng <lengchao at huawei.com>
---
 drivers/nvme/host/tcp.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 1ba659927442..725f80984d54 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -76,6 +76,7 @@ struct nvme_tcp_queue {
 	struct work_struct	io_work;
 	int			io_cpu;
 
+	struct mutex		queue_lock;
 	struct mutex		send_mutex;
 	struct llist_head	req_list;
 	struct list_head	send_list;
@@ -1209,6 +1210,7 @@ static void nvme_tcp_free_queue(struct nvme_ctrl *nctrl, int qid)
 
 	sock_release(queue->sock);
 	kfree(queue->pdu);
+	mutex_destroy(&queue->queue_lock);
 }
 
 static int nvme_tcp_init_connection(struct nvme_tcp_queue *queue)
@@ -1370,6 +1372,7 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl,
 	struct nvme_tcp_queue *queue = &ctrl->queues[qid];
 	int ret, rcv_pdu_size;
 
+	mutex_init(&queue->queue_lock);
 	queue->ctrl = ctrl;
 	init_llist_head(&queue->req_list);
 	INIT_LIST_HEAD(&queue->send_list);
@@ -1388,7 +1391,7 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl,
 	if (ret) {
 		dev_err(nctrl->device,
 			"failed to create socket: %d\n", ret);
-		return ret;
+		goto err_destroy_mutex;
 	}
 
 	/* Single syn retry */
@@ -1497,6 +1500,8 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl,
 err_sock:
 	sock_release(queue->sock);
 	queue->sock = NULL;
+err_destroy_mutex:
+	mutex_destroy(&queue->queue_lock);
 	return ret;
 }
 
@@ -1524,9 +1529,10 @@ static void nvme_tcp_stop_queue(struct nvme_ctrl *nctrl, int qid)
 	struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
 	struct nvme_tcp_queue *queue = &ctrl->queues[qid];
 
-	if (!test_and_clear_bit(NVME_TCP_Q_LIVE, &queue->flags))
-		return;
-	__nvme_tcp_stop_queue(queue);
+	mutex_lock(&queue->queue_lock);
+	if (test_and_clear_bit(NVME_TCP_Q_LIVE, &queue->flags))
+		__nvme_tcp_stop_queue(queue);
+	mutex_unlock(&queue->queue_lock);
 }
 
 static int nvme_tcp_start_queue(struct nvme_ctrl *nctrl, int idx)
-- 
2.16.4