[PATCH v2 2/2] Bluetooth: ISO: Send BIG Create Sync via hci_sync

[Iulia Tanasescu <iulia.tanasescu@xxxxxxx>]

Before issuing the LE BIG Create Sync command, an available BIG handle
is chosen by iterating through the conn_hash list and finding the first
unused value.

If a BIG is terminated, the associated hcons are removed from the list
and the LE BIG Terminate Sync command is sent via hci_sync queue.
However, a new LE BIG Create sync command might be issued via
hci_send_cmd, before the previous BIG sync was terminated. This
can cause the same BIG handle to be reused and the LE BIG Create Sync
to fail with Command Disallowed.

< HCI Command: LE Broadcast Isochronous Group Create Sync (0x08|0x006b)
        BIG Handle: 0x00
        BIG Sync Handle: 0x0002
        Encryption: Unencrypted (0x00)
        Broadcast Code[16]: 00000000000000000000000000000000
        Maximum Number Subevents: 0x00
        Timeout: 20000 ms (0x07d0)
        Number of BIS: 1
        BIS ID: 0x01
> HCI Event: Command Status (0x0f) plen 4
      LE Broadcast Isochronous Group Create Sync (0x08|0x006b) ncmd 1
        Status: Command Disallowed (0x0c)
< HCI Command: LE Broadcast Isochronous Group Terminate Sync (0x08|0x006c)
        BIG Handle: 0x00

This commit fixes the ordering of the LE BIG Create Sync/LE BIG Terminate
Sync commands, to make sure that either the previous BIG sync is
terminated before reusing the handle, or that a new handle is chosen
for a new sync.

Fixes: eca0ae4aea66 ("Bluetooth: Add initial implementation of BIS connections")
Signed-off-by: Iulia Tanasescu <iulia.tanasescu@xxxxxxx>
---
 net/bluetooth/hci_conn.c | 17 ++++++++++++++++-
 net/bluetooth/iso.c      |  9 +++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index b5b78d469d54..d097e308a755 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -2180,7 +2180,15 @@ static bool hci_conn_check_create_big_sync(struct hci_conn *conn)
 	return true;
 }
 
-int hci_le_big_create_sync_pending(struct hci_dev *hdev)
+static void big_create_sync_complete(struct hci_dev *hdev, void *data, int err)
+{
+	bt_dev_dbg(hdev, "");
+
+	if (err)
+		bt_dev_err(hdev, "Unable to create BIG sync: %d", err);
+}
+
+static int big_create_sync(struct hci_dev *hdev, void *data)
 {
 	DEFINE_FLEX(struct hci_cp_le_big_create_sync, pdu, bis, num_bis, 0x11);
 	struct hci_conn *conn;
@@ -2237,6 +2245,13 @@ int hci_le_big_create_sync_pending(struct hci_dev *hdev)
 			    struct_size(pdu, bis, pdu->num_bis), pdu);
 }
 
+int hci_le_big_create_sync_pending(struct hci_dev *hdev)
+{
+	/* Queue big_create_sync */
+	return hci_cmd_sync_queue_once(hdev, big_create_sync,
+				       NULL, big_create_sync_complete);
+}
+
 int hci_le_big_create_sync(struct hci_dev *hdev, struct hci_conn *hcon,
 			   struct bt_iso_qos *qos,
 			   __u16 sync_handle, __u8 num_bis, __u8 bis[])
diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index 9e119da43147..70ea1bbd5e4b 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -1338,6 +1338,13 @@ static void iso_conn_big_sync(struct sock *sk)
 	if (!hdev)
 		return;
 
+	/* hci_le_big_create_sync requires hdev lock to be held, since
+	 * it enqueues the HCI LE BIG Create Sync command via
+	 * hci_cmd_sync_queue_once, which checks hdev flags that might
+	 * change.
+	 */
+	hci_dev_lock(hdev);
+
 	if (!test_and_set_bit(BT_SK_BIG_SYNC, &iso_pi(sk)->flags)) {
 		err = hci_le_big_create_sync(hdev, iso_pi(sk)->conn->hcon,
 					     &iso_pi(sk)->qos,
@@ -1348,6 +1355,8 @@ static void iso_conn_big_sync(struct sock *sk)
 			bt_dev_err(hdev, "hci_le_big_create_sync: %d",
 				   err);
 	}
+
+	hci_dev_unlock(hdev);
 }
 
 static int iso_sock_recvmsg(struct socket *sock, struct msghdr *msg,
-- 
2.43.0