1 files changed, 27 insertions, 12 deletions

diff --git a/sound/core/seq/seq_ports.c b/sound/core/seq/seq_ports.c
index a42e2ce4a726..8f694438ecdd 100644
--- a/sound/core/seq/seq_ports.c
+++ b/sound/core/seq/seq_ports.c
@@ -532,10 +532,11 @@ static int check_and_subscribe_port(struct snd_seq_client *client,
 	return err;
 }
 
-static void delete_and_unsubscribe_port(struct snd_seq_client *client,
-					struct snd_seq_client_port *port,
-					struct snd_seq_subscribers *subs,
-					bool is_src, bool ack)
+/* called with grp->list_mutex held */
+static void __delete_and_unsubscribe_port(struct snd_seq_client *client,
+					  struct snd_seq_client_port *port,
+					  struct snd_seq_subscribers *subs,
+					  bool is_src, bool ack)
 {
 	struct snd_seq_port_subs_info *grp;
 	struct list_head *list;
@@ -543,7 +544,6 @@ static void delete_and_unsubscribe_port(struct snd_seq_client *client,
 
 	grp = is_src ? &port->c_src : &port->c_dest;
 	list = is_src ? &subs->src_list : &subs->dest_list;
-	down_write(&grp->list_mutex);
 	write_lock_irq(&grp->list_lock);
 	empty = list_empty(list);
 	if (!empty)
@@ -553,6 +553,18 @@ static void delete_and_unsubscribe_port(struct snd_seq_client *client,
 
 	if (!empty)
 		unsubscribe_port(client, port, grp, &subs->info, ack);
+}
+
+static void delete_and_unsubscribe_port(struct snd_seq_client *client,
+					struct snd_seq_client_port *port,
+					struct snd_seq_subscribers *subs,
+					bool is_src, bool ack)
+{
+	struct snd_seq_port_subs_info *grp;
+
+	grp = is_src ? &port->c_src : &port->c_dest;
+	down_write(&grp->list_mutex);
+	__delete_and_unsubscribe_port(client, port, subs, is_src, ack);
 	up_write(&grp->list_mutex);
 }
 
@@ -608,27 +620,30 @@ int snd_seq_port_disconnect(struct snd_seq_client *connector,
 			    struct snd_seq_client_port *dest_port,
 			    struct snd_seq_port_subscribe *info)
 {
-	struct snd_seq_port_subs_info *src = &src_port->c_src;
+	struct snd_seq_port_subs_info *dest = &dest_port->c_dest;
 	struct snd_seq_subscribers *subs;
 	int err = -ENOENT;
 
-	down_write(&src->list_mutex);
+	/* always start from deleting the dest port for avoiding concurrent
+	 * deletions
+	 */
+	down_write(&dest->list_mutex);
 	/* look for the connection */
-	list_for_each_entry(subs, &src->list_head, src_list) {
+	list_for_each_entry(subs, &dest->list_head, dest_list) {
 		if (match_subs_info(info, &subs->info)) {
-			atomic_dec(&subs->ref_count); /* mark as not ready */
+			__delete_and_unsubscribe_port(dest_client, dest_port,
+						      subs, false,
+						      connector->number != dest_client->number);
 			err = 0;
 			break;
 		}
 	}
-	up_write(&src->list_mutex);
+	up_write(&dest->list_mutex);
 	if (err < 0)
 		return err;
 
 	delete_and_unsubscribe_port(src_client, src_port, subs, true,
 				    connector->number != src_client->number);
-	delete_and_unsubscribe_port(dest_client, dest_port, subs, false,
-				    connector->number != dest_client->number);
 	kfree(subs);
 	return 0;
 }