Bluetooth: SCO: Use kref to track lifetime of sco_conn

This make use of kref to keep track of reference of sco_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 sco_sock_set_timer on __sco_sock_close
since at that point it is useless to set a timer as the sk will be freed
there is nothing to be done in sco_sock_timeout.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index 1c7252a3686694284b0b1e1101e3d16b90d906c4..1b8e468d24cf5b6b44adaedfb42ef30058ccda27 100644 (file)
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -51,6 +51,7 @@ struct sco_conn {
        struct delayed_work     timeout_work;
 
        unsigned int    mtu;
+       struct kref     ref;
 };
 
 #define sco_conn_lock(c)       spin_lock(&c->lock)
@@ -76,6 +77,49 @@ struct sco_pinfo {
 #define SCO_CONN_TIMEOUT       (HZ * 40)
 #define SCO_DISCONN_TIMEOUT    (HZ * 2)
 
+static void sco_conn_free(struct kref *ref)
+{
+       struct sco_conn *conn = container_of(ref, struct sco_conn, ref);
+
+       BT_DBG("conn %p", conn);
+
+       if (conn->sk)
+               sco_pi(conn->sk)->conn = NULL;
+
+       if (conn->hcon) {
+               conn->hcon->sco_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 sco_conn_put(struct sco_conn *conn)
+{
+       if (!conn)
+               return;
+
+       BT_DBG("conn %p refcnt %d", conn, kref_read(&conn->ref));
+
+       kref_put(&conn->ref, sco_conn_free);
+}
+
+static struct sco_conn *sco_conn_hold_unless_zero(struct sco_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 *sco_sock_hold(struct sco_conn *conn)
 {
        if (!conn || !bt_sock_linked(&sco_sk_list, conn->sk))
@@ -92,6 +136,10 @@ static void sco_sock_timeout(struct work_struct *work)
                                             timeout_work.work);
        struct sock *sk;
 
+       conn = sco_conn_hold_unless_zero(conn);
+       if (!conn)
+               return;
+
        sco_conn_lock(conn);
        if (!conn->hcon) {
                sco_conn_unlock(conn);
@@ -99,6 +147,7 @@ static void sco_sock_timeout(struct work_struct *work)
        }
        sk = sco_sock_hold(conn);
        sco_conn_unlock(conn);
+       sco_conn_put(conn);
 
        if (!sk)
                return;
@@ -136,9 +185,14 @@ static struct sco_conn *sco_conn_add(struct hci_conn *hcon)
 {
        struct sco_conn *conn = hcon->sco_data;
 
+       conn = sco_conn_hold_unless_zero(conn);
        if (conn) {
-               if (!conn->hcon)
+               if (!conn->hcon) {
+                       sco_conn_lock(conn);
                        conn->hcon = hcon;
+                       sco_conn_unlock(conn);
+               }
+               sco_conn_put(conn);
                return conn;
        }
 
@@ -146,6 +200,7 @@ static struct sco_conn *sco_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, sco_sock_timeout);
 
@@ -170,17 +225,15 @@ static void sco_chan_del(struct sock *sk, int err)
        struct sco_conn *conn;
 
        conn = sco_pi(sk)->conn;
+       sco_pi(sk)->conn = NULL;
 
        BT_DBG("sk %p, conn %p, err %d", sk, conn, err);
 
        if (conn) {
                sco_conn_lock(conn);
                conn->sk = NULL;
-               sco_pi(sk)->conn = NULL;
                sco_conn_unlock(conn);
-
-               if (conn->hcon)
-                       hci_conn_drop(conn->hcon);
+               sco_conn_put(conn);
        }
 
        sk->sk_state = BT_CLOSED;
@@ -195,29 +248,28 @@ static void sco_conn_del(struct hci_conn *hcon, int err)
        struct sco_conn *conn = hcon->sco_data;
        struct sock *sk;
 
+       conn = sco_conn_hold_unless_zero(conn);
        if (!conn)
                return;
 
        BT_DBG("hcon %p conn %p, err %d", hcon, conn, err);
 
-       /* Kill socket */
        sco_conn_lock(conn);
        sk = sco_sock_hold(conn);
        sco_conn_unlock(conn);
+       sco_conn_put(conn);
 
-       if (sk) {
-               lock_sock(sk);
-               sco_sock_clear_timer(sk);
-               sco_chan_del(sk, err);
-               release_sock(sk);
-               sock_put(sk);
+       if (!sk) {
+               sco_conn_put(conn);
+               return;
        }
 
-       /* Ensure no more work items will run before freeing conn. */
-       cancel_delayed_work_sync(&conn->timeout_work);
-
-       hcon->sco_data = NULL;
-       kfree(conn);
+       /* Kill socket */
+       lock_sock(sk);
+       sco_sock_clear_timer(sk);
+       sco_chan_del(sk, err);
+       release_sock(sk);
+       sock_put(sk);
 }
 
 static void __sco_chan_add(struct sco_conn *conn, struct sock *sk,
@@ -401,6 +453,8 @@ static void sco_sock_destruct(struct sock *sk)
 {
        BT_DBG("sk %p", sk);
 
+       sco_conn_put(sco_pi(sk)->conn);
+
        skb_queue_purge(&sk->sk_receive_queue);
        skb_queue_purge(&sk->sk_write_queue);
 }
@@ -448,17 +502,6 @@ static void __sco_sock_close(struct sock *sk)
 
        case BT_CONNECTED:
        case BT_CONFIG:
-               if (sco_pi(sk)->conn->hcon) {
-                       sk->sk_state = BT_DISCONN;
-                       sco_sock_set_timer(sk, SCO_DISCONN_TIMEOUT);
-                       sco_conn_lock(sco_pi(sk)->conn);
-                       hci_conn_drop(sco_pi(sk)->conn->hcon);
-                       sco_pi(sk)->conn->hcon = NULL;
-                       sco_conn_unlock(sco_pi(sk)->conn);
-               } else
-                       sco_chan_del(sk, ECONNRESET);
-               break;
-
        case BT_CONNECT2:
        case BT_CONNECT:
        case BT_DISCONN: