nvmet-tcp: avoid circular locking dependency on install_queue()

nvmet_tcp_install_queue() is driven from the ->io_work workqueue
function, but will call flush_workqueue() which might trigger
->release_work() which in itself calls flush_work on ->io_work.

To avoid that check for pending queue in disconnecting status,
and return 'controller busy' when we reached a certain threshold.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index 4dc60cbcb205bc13ba2d54c0f7e8e0a1462a15fc..6a1e6bb80062d4753501e07cbcba43870fc00eeb 100644 (file)
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -25,6 +25,7 @@
 
 #define NVMET_TCP_DEF_INLINE_DATA_SIZE (4 * PAGE_SIZE)
 #define NVMET_TCP_MAXH2CDATA           0x400000 /* 16M arbitrary limit */
+#define NVMET_TCP_BACKLOG 128
 
 static int param_store_val(const char *str, int *val, int min, int max)
 {
@@ -2067,7 +2068,7 @@ static int nvmet_tcp_add_port(struct nvmet_port *nport)
                goto err_sock;
        }
 
-       ret = kernel_listen(port->sock, 128);
+       ret = kernel_listen(port->sock, NVMET_TCP_BACKLOG);
        if (ret) {
                pr_err("failed to listen %d on port sock\n", ret);
                goto err_sock;
@@ -2133,8 +2134,19 @@ static u16 nvmet_tcp_install_queue(struct nvmet_sq *sq)
                container_of(sq, struct nvmet_tcp_queue, nvme_sq);
 
        if (sq->qid == 0) {
-               /* Let inflight controller teardown complete */
-               flush_workqueue(nvmet_wq);
+               struct nvmet_tcp_queue *q;
+               int pending = 0;
+
+               /* Check for pending controller teardown */
+               mutex_lock(&nvmet_tcp_queue_mutex);
+               list_for_each_entry(q, &nvmet_tcp_queue_list, queue_list) {
+                       if (q->nvme_sq.ctrl == sq->ctrl &&
+                           q->state == NVMET_TCP_Q_DISCONNECTING)
+                               pending++;
+               }
+               mutex_unlock(&nvmet_tcp_queue_mutex);
+               if (pending > NVMET_TCP_BACKLOG)
+                       return NVME_SC_CONNECT_CTRL_BUSY;
        }
 
        queue->nr_cmds = sq->size * 2;