Bluetooth: ISO: Use kref to track lifetime of iso_conn

This make use of kref to keep track of reference of iso_conn which
allows better tracking of its lifetime with usage of things like
kref_get_unless_zero in a similar way as used in l2cap_chan.

In addition to it remove call to iso_sock_set_timer on iso_sock_disconn
since at that point it is useless to set a timer as the sk will be freed
there is nothing to be done in iso_sock_timeout.

Fixes: ccf74f2390d6 ("Bluetooth: Add BTPROTO_ISO socket type")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index 9e119da43147908543db7e4780e417c7d0cecfb1..24e78ada9ad23286def2d2ad7239f3eae4ea0993 100644 (file)
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -35,6 +35,7 @@ struct iso_conn {
        struct sk_buff  *rx_skb;
        __u32           rx_len;
        __u16           tx_sn;
+       struct kref     ref;
 };
 
 #define iso_conn_lock(c)       spin_lock(&(c)->lock)
@@ -93,6 +94,49 @@ static struct sock *iso_get_sock(bdaddr_t *src, bdaddr_t *dst,
 #define ISO_CONN_TIMEOUT       (HZ * 40)
 #define ISO_DISCONN_TIMEOUT    (HZ * 2)
 
+static void iso_conn_free(struct kref *ref)
+{
+       struct iso_conn *conn = container_of(ref, struct iso_conn, ref);
+
+       BT_DBG("conn %p", conn);
+
+       if (conn->sk)
+               iso_pi(conn->sk)->conn = NULL;
+
+       if (conn->hcon) {
+               conn->hcon->iso_data = NULL;
+               hci_conn_drop(conn->hcon);
+       }
+
+       /* Ensure no more work items will run since hci_conn has been dropped */
+       disable_delayed_work_sync(&conn->timeout_work);
+
+       kfree(conn);
+}
+
+static void iso_conn_put(struct iso_conn *conn)
+{
+       if (!conn)
+               return;
+
+       BT_DBG("conn %p refcnt %d", conn, kref_read(&conn->ref));
+
+       kref_put(&conn->ref, iso_conn_free);
+}
+
+static struct iso_conn *iso_conn_hold_unless_zero(struct iso_conn *conn)
+{
+       if (!conn)
+               return NULL;
+
+       BT_DBG("conn %p refcnt %u", conn, kref_read(&conn->ref));
+
+       if (!kref_get_unless_zero(&conn->ref))
+               return NULL;
+
+       return conn;
+}
+
 static struct sock *iso_sock_hold(struct iso_conn *conn)
 {
        if (!conn || !bt_sock_linked(&iso_sk_list, conn->sk))
@@ -109,9 +153,14 @@ static void iso_sock_timeout(struct work_struct *work)
                                             timeout_work.work);
        struct sock *sk;
 
+       conn = iso_conn_hold_unless_zero(conn);
+       if (!conn)
+               return;
+
        iso_conn_lock(conn);
        sk = iso_sock_hold(conn);
        iso_conn_unlock(conn);
+       iso_conn_put(conn);
 
        if (!sk)
                return;
@@ -149,9 +198,14 @@ static struct iso_conn *iso_conn_add(struct hci_conn *hcon)
 {
        struct iso_conn *conn = hcon->iso_data;
 
+       conn = iso_conn_hold_unless_zero(conn);
        if (conn) {
-               if (!conn->hcon)
+               if (!conn->hcon) {
+                       iso_conn_lock(conn);
                        conn->hcon = hcon;
+                       iso_conn_unlock(conn);
+               }
+               iso_conn_put(conn);
                return conn;
        }
 
@@ -159,6 +213,7 @@ static struct iso_conn *iso_conn_add(struct hci_conn *hcon)
        if (!conn)
                return NULL;
 
+       kref_init(&conn->ref);
        spin_lock_init(&conn->lock);
        INIT_DELAYED_WORK(&conn->timeout_work, iso_sock_timeout);
 
@@ -178,17 +233,15 @@ static void iso_chan_del(struct sock *sk, int err)
        struct sock *parent;
 
        conn = iso_pi(sk)->conn;
+       iso_pi(sk)->conn = NULL;
 
        BT_DBG("sk %p, conn %p, err %d", sk, conn, err);
 
        if (conn) {
                iso_conn_lock(conn);
                conn->sk = NULL;
-               iso_pi(sk)->conn = NULL;
                iso_conn_unlock(conn);
-
-               if (conn->hcon)
-                       hci_conn_drop(conn->hcon);
+               iso_conn_put(conn);
        }
 
        sk->sk_state = BT_CLOSED;
@@ -210,6 +263,7 @@ static void iso_conn_del(struct hci_conn *hcon, int err)
        struct iso_conn *conn = hcon->iso_data;
        struct sock *sk;
 
+       conn = iso_conn_hold_unless_zero(conn);
        if (!conn)
                return;
 
@@ -219,20 +273,18 @@ static void iso_conn_del(struct hci_conn *hcon, int err)
        iso_conn_lock(conn);
        sk = iso_sock_hold(conn);
        iso_conn_unlock(conn);
+       iso_conn_put(conn);
 
-       if (sk) {
-               lock_sock(sk);
-               iso_sock_clear_timer(sk);
-               iso_chan_del(sk, err);
-               release_sock(sk);
-               sock_put(sk);
+       if (!sk) {
+               iso_conn_put(conn);
+               return;
        }
 
-       /* Ensure no more work items will run before freeing conn. */
-       cancel_delayed_work_sync(&conn->timeout_work);
-
-       hcon->iso_data = NULL;
-       kfree(conn);
+       lock_sock(sk);
+       iso_sock_clear_timer(sk);
+       iso_chan_del(sk, err);
+       release_sock(sk);
+       sock_put(sk);
 }
 
 static int __iso_chan_add(struct iso_conn *conn, struct sock *sk,
@@ -652,6 +704,8 @@ static void iso_sock_destruct(struct sock *sk)
 {
        BT_DBG("sk %p", sk);
 
+       iso_conn_put(iso_pi(sk)->conn);
+
        skb_queue_purge(&sk->sk_receive_queue);
        skb_queue_purge(&sk->sk_write_queue);
 }
@@ -711,6 +765,7 @@ static void iso_sock_disconn(struct sock *sk)
                 */
                if (bis_sk) {
                        hcon->state = BT_OPEN;
+                       hcon->iso_data = NULL;
                        iso_pi(sk)->conn->hcon = NULL;
                        iso_sock_clear_timer(sk);
                        iso_chan_del(sk, bt_to_errno(hcon->abort_reason));
@@ -720,7 +775,6 @@ static void iso_sock_disconn(struct sock *sk)
        }
 
        sk->sk_state = BT_DISCONN;
-       iso_sock_set_timer(sk, ISO_DISCONN_TIMEOUT);
        iso_conn_lock(iso_pi(sk)->conn);
        hci_conn_drop(iso_pi(sk)->conn->hcon);
        iso_pi(sk)->conn->hcon = NULL;