Bluetooth: Revert to mutexes from RCU list

Usage of RCU list looks not reasonalbe for a number of reasons:
our code sleep and we had to use socket spinlocks. Most parts
of code are updaters thus there is little sense to use RCU.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Reviewed-by: Ulisses Furquim <ulisses@profusion.mobi>
Acked-by: Gustavo F. Padovan <padovan@profusion.mobi>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

2 files changed, 109 insertions, 67 deletions

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 63539f940572..8e8e9e93fb34 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -77,36 +77,24 @@ static void l2cap_send_disconn_req(struct l2cap_conn *conn,
 
 static struct l2cap_chan *__l2cap_get_chan_by_dcid(struct l2cap_conn *conn, u16 cid)
 {
-        struct l2cap_chan *c, *r = NULL;
-
-        rcu_read_lock();
+        struct l2cap_chan *c;
 
-        list_for_each_entry_rcu(c, &conn->chan_l, list) {
-                if (c->dcid == cid) {
-                        r = c;
-                        break;
-                }
+        list_for_each_entry(c, &conn->chan_l, list) {
+                if (c->dcid == cid)
+                        return c;
         }
-
-        rcu_read_unlock();
-        return r;
+        return NULL;
 }
 
 static struct l2cap_chan *__l2cap_get_chan_by_scid(struct l2cap_conn *conn, u16 cid)
 {
-        struct l2cap_chan *c, *r = NULL;
-
-        rcu_read_lock();
+        struct l2cap_chan *c;
 
-        list_for_each_entry_rcu(c, &conn->chan_l, list) {
-                if (c->scid == cid) {
-                        r = c;
-                        break;
-                }
+        list_for_each_entry(c, &conn->chan_l, list) {
+                if (c->scid == cid)
+                        return c;
         }
-
-        rcu_read_unlock();
-        return r;
+        return NULL;
 }
 
 /* Find channel with given SCID.
@@ -115,36 +103,32 @@ static struct l2cap_chan *l2cap_get_chan_by_scid(struct l2cap_conn *conn, u16 ci
 {
         struct l2cap_chan *c;
 
+        mutex_lock(&conn->chan_lock);
         c = __l2cap_get_chan_by_scid(conn, cid);
-        if (c)
-                lock_sock(c->sk);
+        mutex_unlock(&conn->chan_lock);
+
         return c;
 }
 
 static struct l2cap_chan *__l2cap_get_chan_by_ident(struct l2cap_conn *conn, u8 ident)
 {
-        struct l2cap_chan *c, *r = NULL;
-
-        rcu_read_lock();
+        struct l2cap_chan *c;
 
-        list_for_each_entry_rcu(c, &conn->chan_l, list) {
-                if (c->ident == ident) {
-                        r = c;
-                        break;
-                }
+        list_for_each_entry(c, &conn->chan_l, list) {
+                if (c->ident == ident)
+                        return c;
         }
-
-        rcu_read_unlock();
-        return r;
+        return NULL;
 }
 
 static inline struct l2cap_chan *l2cap_get_chan_by_ident(struct l2cap_conn *conn, u8 ident)
 {
         struct l2cap_chan *c;
 
+        mutex_lock(&conn->chan_lock);
         c = __l2cap_get_chan_by_ident(conn, ident);
-        if (c)
-                lock_sock(c->sk);
+        mutex_unlock(&conn->chan_lock);
+
         return c;
 }
 
@@ -228,11 +212,13 @@ static void l2cap_chan_timeout(struct work_struct *work)
 {
         struct l2cap_chan *chan = container_of(work, struct l2cap_chan,
                                                         chan_timer.work);
+        struct l2cap_conn *conn = chan->conn;
         struct sock *sk = chan->sk;
         int reason;
 
         BT_DBG("chan %p state %s", chan, state_to_string(chan->state));
 
+        mutex_lock(&conn->chan_lock);
         lock_sock(sk);
 
         if (chan->state == BT_CONNECTED || chan->state == BT_CONFIG)
@@ -248,6 +234,8 @@ static void l2cap_chan_timeout(struct work_struct *work)
         release_sock(sk);
 
         chan->ops->close(chan->data);
+        mutex_unlock(&conn->chan_lock);
+
         l2cap_chan_put(chan);
 }
 
@@ -331,7 +319,9 @@ static void l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan)
 
         l2cap_chan_hold(chan);
 
-        list_add_rcu(&chan->list, &conn->chan_l);
+        mutex_lock(&conn->chan_lock);
+        list_add(&chan->list, &conn->chan_l);
+        mutex_unlock(&conn->chan_lock);
 }
 
 /* Delete channel.
@@ -348,8 +338,7 @@ static void l2cap_chan_del(struct l2cap_chan *chan, int err)
 
         if (conn) {
                 /* Delete from channel list */
-                list_del_rcu(&chan->list);
-                synchronize_rcu();
+                list_del(&chan->list);
 
                 l2cap_chan_put(chan);
 
@@ -400,10 +389,12 @@ static void l2cap_chan_cleanup_listen(struct sock *parent)
         /* Close not yet accepted channels */
         while ((sk = bt_accept_dequeue(parent, NULL))) {
                 struct l2cap_chan *chan = l2cap_pi(sk)->chan;
+
                 __clear_chan_timer(chan);
                 lock_sock(sk);
                 l2cap_chan_close(chan, ECONNRESET);
                 release_sock(sk);
+
                 chan->ops->close(chan->data);
         }
 }
@@ -718,13 +709,13 @@ static void l2cap_send_disconn_req(struct l2cap_conn *conn, struct l2cap_chan *c
 /* ---- L2CAP connections ---- */
 static void l2cap_conn_start(struct l2cap_conn *conn)
 {
-        struct l2cap_chan *chan;
+        struct l2cap_chan *chan, *tmp;
 
         BT_DBG("conn %p", conn);
 
-        rcu_read_lock();
+        mutex_lock(&conn->chan_lock);
 
-        list_for_each_entry_rcu(chan, &conn->chan_l, list) {
+        list_for_each_entry_safe(chan, tmp, &conn->chan_l, list) {
                 struct sock *sk = chan->sk;
 
                 bh_lock_sock(sk);
@@ -804,7 +795,7 @@ static void l2cap_conn_start(struct l2cap_conn *conn)
                 bh_unlock_sock(sk);
         }
 
-        rcu_read_unlock();
+        mutex_unlock(&conn->chan_lock);
 }
 
 /* Find socket with cid and source bdaddr.
@@ -916,9 +907,9 @@ static void l2cap_conn_ready(struct l2cap_conn *conn)
         if (conn->hcon->out && conn->hcon->type == LE_LINK)
                 smp_conn_security(conn, conn->hcon->pending_sec_level);
 
-        rcu_read_lock();
+        mutex_lock(&conn->chan_lock);
 
-        list_for_each_entry_rcu(chan, &conn->chan_l, list) {
+        list_for_each_entry(chan, &conn->chan_l, list) {
                 struct sock *sk = chan->sk;
 
                 bh_lock_sock(sk);
@@ -938,7 +929,7 @@ static void l2cap_conn_ready(struct l2cap_conn *conn)
                 bh_unlock_sock(sk);
         }
 
-        rcu_read_unlock();
+        mutex_unlock(&conn->chan_lock);
 }
 
 /* Notify sockets that we cannot guaranty reliability anymore */
@@ -948,16 +939,16 @@ static void l2cap_conn_unreliable(struct l2cap_conn *conn, int err)
 
         BT_DBG("conn %p", conn);
 
-        rcu_read_lock();
+        mutex_lock(&conn->chan_lock);
 
-        list_for_each_entry_rcu(chan, &conn->chan_l, list) {
+        list_for_each_entry(chan, &conn->chan_l, list) {
                 struct sock *sk = chan->sk;
 
                 if (test_bit(FLAG_FORCE_RELIABLE, &chan->flags))
                         sk->sk_err = err;
         }
 
-        rcu_read_unlock();
+        mutex_unlock(&conn->chan_lock);
 }
 
 static void l2cap_info_timeout(struct work_struct *work)
@@ -984,6 +975,8 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err)
 
         kfree_skb(conn->rx_skb);
 
+        mutex_lock(&conn->chan_lock);
+
         /* Kill channels */
         list_for_each_entry_safe(chan, l, &conn->chan_l, list) {
                 sk = chan->sk;
@@ -993,6 +986,8 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err)
                 chan->ops->close(chan->data);
         }
 
+        mutex_unlock(&conn->chan_lock);
+
         hci_chan_del(conn->hchan);
 
         if (conn->info_state & L2CAP_INFO_FEAT_MASK_REQ_SENT)
@@ -1050,6 +1045,7 @@ static struct l2cap_conn *l2cap_conn_add(struct hci_conn *hcon, u8 status)
         conn->feat_mask = 0;
 
         spin_lock_init(&conn->lock);
+        mutex_init(&conn->chan_lock);
 
         INIT_LIST_HEAD(&conn->chan_l);
 
@@ -1792,9 +1788,9 @@ static void l2cap_raw_recv(struct l2cap_conn *conn, struct sk_buff *skb)
 
         BT_DBG("conn %p", conn);
 
-        rcu_read_lock();
+        mutex_lock(&conn->chan_lock);
 
-        list_for_each_entry_rcu(chan, &conn->chan_l, list) {
+        list_for_each_entry(chan, &conn->chan_l, list) {
                 struct sock *sk = chan->sk;
                 if (chan->chan_type != L2CAP_CHAN_RAW)
                         continue;
@@ -1810,7 +1806,7 @@ static void l2cap_raw_recv(struct l2cap_conn *conn, struct sk_buff *skb)
                         kfree_skb(nskb);
         }
 
-        rcu_read_unlock();
+        mutex_unlock(&conn->chan_lock);
 }
 
 /* ---- L2CAP signalling commands ---- */
@@ -2600,6 +2596,7 @@ static inline int l2cap_connect_req(struct l2cap_conn *conn, struct l2cap_cmd_hd
 
         parent = pchan->sk;
 
+        mutex_lock(&conn->chan_lock);
         lock_sock(parent);
 
         /* Check if the ACL is secure enough (if not SDP) */
@@ -2673,6 +2670,7 @@ static inline int l2cap_connect_req(struct l2cap_conn *conn, struct l2cap_cmd_hd
 
 response:
         release_sock(parent);
+        mutex_unlock(&conn->chan_lock);
 
 sendresp:
         rsp.scid   = cpu_to_le16(scid);
@@ -2714,6 +2712,7 @@ static inline int l2cap_connect_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hd
         struct l2cap_chan *chan;
         struct sock *sk;
         u8 req[128];
+        int err;
 
         scid   = __le16_to_cpu(rsp->scid);
         dcid   = __le16_to_cpu(rsp->dcid);
@@ -2723,17 +2722,26 @@ static inline int l2cap_connect_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hd
         BT_DBG("dcid 0x%4.4x scid 0x%4.4x result 0x%2.2x status 0x%2.2x",
                                                 dcid, scid, result, status);
 
+        mutex_lock(&conn->chan_lock);
+
         if (scid) {
-                chan = l2cap_get_chan_by_scid(conn, scid);
-                if (!chan)
-                        return -EFAULT;
+                chan = __l2cap_get_chan_by_scid(conn, scid);
+                if (!chan) {
+                        err = -EFAULT;
+                        goto unlock;
+                }
         } else {
-                chan = l2cap_get_chan_by_ident(conn, cmd->ident);
-                if (!chan)
-                        return -EFAULT;
+                chan = __l2cap_get_chan_by_ident(conn, cmd->ident);
+                if (!chan) {
+                        err = -EFAULT;
+                        goto unlock;
+                }
         }
 
+        err = 0;
+
         sk = chan->sk;
+        lock_sock(sk);
 
         switch (result) {
         case L2CAP_CR_SUCCESS:
@@ -2760,7 +2768,11 @@ static inline int l2cap_connect_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hd
         }
 
         release_sock(sk);
-        return 0;
+
+unlock:
+        mutex_unlock(&conn->chan_lock);
+
+        return err;
 }
 
 static inline void set_default_fcs(struct l2cap_chan *chan)
@@ -2793,6 +2805,7 @@ static inline int l2cap_config_req(struct l2cap_conn *conn, struct l2cap_cmd_hdr
                 return -ENOENT;
 
         sk = chan->sk;
+        lock_sock(sk);
 
         if (chan->state != BT_CONFIG && chan->state != BT_CONNECT2) {
                 struct l2cap_cmd_rej_cid rej;
@@ -2905,6 +2918,7 @@ static inline int l2cap_config_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hdr
                 return 0;
 
         sk = chan->sk;
+        lock_sock(sk);
 
         switch (result) {
         case L2CAP_CONF_SUCCESS:
@@ -3006,11 +3020,16 @@ static inline int l2cap_disconnect_req(struct l2cap_conn *conn, struct l2cap_cmd
 
         BT_DBG("scid 0x%4.4x dcid 0x%4.4x", scid, dcid);
 
-        chan = l2cap_get_chan_by_scid(conn, dcid);
-        if (!chan)
+        mutex_lock(&conn->chan_lock);
+
+        chan = __l2cap_get_chan_by_scid(conn, dcid);
+        if (!chan) {
+                mutex_unlock(&conn->chan_lock);
                 return 0;
+        }
 
         sk = chan->sk;
+        lock_sock(sk);
 
         rsp.dcid = cpu_to_le16(chan->scid);
         rsp.scid = cpu_to_le16(chan->dcid);
@@ -3022,6 +3041,9 @@ static inline int l2cap_disconnect_req(struct l2cap_conn *conn, struct l2cap_cmd
         release_sock(sk);
 
         chan->ops->close(chan->data);
+
+        mutex_unlock(&conn->chan_lock);
+
         return 0;
 }
 
@@ -3037,16 +3059,24 @@ static inline int l2cap_disconnect_rsp(struct l2cap_conn *conn, struct l2cap_cmd
 
         BT_DBG("dcid 0x%4.4x scid 0x%4.4x", dcid, scid);
 
-        chan = l2cap_get_chan_by_scid(conn, scid);
-        if (!chan)
+        mutex_lock(&conn->chan_lock);
+
+        chan = __l2cap_get_chan_by_scid(conn, scid);
+        if (!chan) {
+                mutex_unlock(&conn->chan_lock);
                 return 0;
+        }
 
         sk = chan->sk;
+        lock_sock(sk);
 
         l2cap_chan_del(chan, 0);
         release_sock(sk);
 
         chan->ops->close(chan->data);
+
+        mutex_unlock(&conn->chan_lock);
+
         return 0;
 }
 
@@ -4205,6 +4235,7 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk
         }
 
         sk = chan->sk;
+        lock_sock(sk);
 
         BT_DBG("chan %p, len %d", chan, skb->len);
 
@@ -4492,9 +4523,9 @@ int l2cap_security_cfm(struct hci_conn *hcon, u8 status, u8 encrypt)
                 cancel_delayed_work(&conn->security_timer);
         }
 
-        rcu_read_lock();
+        mutex_lock(&conn->chan_lock);
 
-        list_for_each_entry_rcu(chan, &conn->chan_l, list) {
+        list_for_each_entry(chan, &conn->chan_l, list) {
                 struct sock *sk = chan->sk;
 
                 bh_lock_sock(sk);
@@ -4574,7 +4605,7 @@ int l2cap_security_cfm(struct hci_conn *hcon, u8 status, u8 encrypt)
                 bh_unlock_sock(sk);
         }
 
-        rcu_read_unlock();
+        mutex_unlock(&conn->chan_lock);
 
         return 0;
 }
@@ -4635,6 +4666,7 @@ int l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
 
                 if (chan && chan->sk) {
                         struct sock *sk = chan->sk;
+                        lock_sock(sk);
 
                         if (chan->imtu < len - L2CAP_HDR_SIZE) {
                                 BT_ERR("Frame exceeding recv MTU (len %d, "
diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index b48d6c1b9db6..1273fcbeec28 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -796,6 +796,7 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
 {
         struct sock *sk = sock->sk;
         struct l2cap_chan *chan;
+        struct l2cap_conn *conn;
         int err = 0;
 
         BT_DBG("sock %p, sk %p", sock, sk);
@@ -804,6 +805,10 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
                 return 0;
 
         chan = l2cap_pi(sk)->chan;
+        conn = chan->conn;
+
+        if (conn)
+                mutex_lock(&conn->chan_lock);
 
         lock_sock(sk);
         if (!sk->sk_shutdown) {
@@ -811,6 +816,7 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
                         err = __l2cap_wait_ack(sk);
 
                 sk->sk_shutdown = SHUTDOWN_MASK;
+
                 l2cap_chan_close(chan, 0);
 
                 if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime)
@@ -822,6 +828,10 @@ static int l2cap_sock_shutdown(struct socket *sock, int how)
                 err = -sk->sk_err;
 
         release_sock(sk);
+
+        if (conn)
+                mutex_unlock(&conn->chan_lock);
+
         return err;
 }