Bluetooth: Remove the send_lock spinlock from ERTM

Using a lock to deal with the ERTM race condition - interruption with
new data from the hci layer - is wrong. We should use the native skb
backlog queue.

Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 1 insertions, 27 deletions

diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index f6e46fdddd2b..dc8601fc2404 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -1562,16 +1562,11 @@ static int l2cap_retransmit_frames(struct sock *sk)
         struct l2cap_pinfo *pi = l2cap_pi(sk);
         int ret;
 
-        spin_lock_bh(&pi->send_lock);
-
         if (!skb_queue_empty(TX_QUEUE(sk)))
                 sk->sk_send_head = TX_QUEUE(sk)->next;
 
         pi->next_tx_seq = pi->expected_ack_seq;
         ret = l2cap_ertm_send(sk);
-
-        spin_unlock_bh(&pi->send_lock);
-
         return ret;
 }
 
@@ -1579,7 +1574,6 @@ static void l2cap_send_ack(struct l2cap_pinfo *pi)
 {
         struct sock *sk = (struct sock *)pi;
         u16 control = 0;
-        int nframes;
 
         control |= pi->buffer_seq << L2CAP_CTRL_REQSEQ_SHIFT;
 
@@ -1590,11 +1584,7 @@ static void l2cap_send_ack(struct l2cap_pinfo *pi)
                 return;
         }
 
-        spin_lock_bh(&pi->send_lock);
-        nframes = l2cap_ertm_send(sk);
-        spin_unlock_bh(&pi->send_lock);
-
-        if (nframes > 0)
+        if (l2cap_ertm_send(sk) > 0)
                 return;
 
         control |= L2CAP_SUPER_RCV_READY;
@@ -1789,10 +1779,8 @@ static inline int l2cap_sar_segment_sdu(struct sock *sk, struct msghdr *msg, siz
                 size += buflen;
         }
         skb_queue_splice_tail(&sar_queue, TX_QUEUE(sk));
-        spin_lock_bh(&pi->send_lock);
         if (sk->sk_send_head == NULL)
                 sk->sk_send_head = sar_queue.next;
-        spin_unlock_bh(&pi->send_lock);
 
         return size;
 }
@@ -1864,14 +1852,9 @@ static int l2cap_sock_sendmsg(struct kiocb *iocb, struct socket *sock, struct ms
                         }
                         __skb_queue_tail(TX_QUEUE(sk), skb);
 
-                        if (pi->mode == L2CAP_MODE_ERTM)
-                                spin_lock_bh(&pi->send_lock);
-
                         if (sk->sk_send_head == NULL)
                                 sk->sk_send_head = skb;
 
-                        if (pi->mode == L2CAP_MODE_ERTM)
-                                spin_unlock_bh(&pi->send_lock);
                 } else {
                 /* Segment SDU into multiples PDUs */
                         err = l2cap_sar_segment_sdu(sk, msg, len);
@@ -1887,9 +1870,7 @@ static int l2cap_sock_sendmsg(struct kiocb *iocb, struct socket *sock, struct ms
                                 err = len;
                                 break;
                         }
-                        spin_lock_bh(&pi->send_lock);
                         err = l2cap_ertm_send(sk);
-                        spin_unlock_bh(&pi->send_lock);
                 }
 
                 if (err >= 0)
@@ -2464,7 +2445,6 @@ static inline void l2cap_ertm_init(struct sock *sk)
 
         __skb_queue_head_init(SREJ_QUEUE(sk));
         __skb_queue_head_init(BUSY_QUEUE(sk));
-        spin_lock_init(&l2cap_pi(sk)->send_lock);
 
         INIT_WORK(&l2cap_pi(sk)->busy_work, l2cap_busy_work);
 }
@@ -3462,9 +3442,7 @@ static inline void l2cap_send_i_or_rr_or_rnr(struct sock *sk)
         if (pi->conn_state & L2CAP_CONN_REMOTE_BUSY)
                 l2cap_retransmit_frames(sk);
 
-        spin_lock_bh(&pi->send_lock);
         l2cap_ertm_send(sk);
-        spin_unlock_bh(&pi->send_lock);
 
         if (!(pi->conn_state & L2CAP_CONN_LOCAL_BUSY) &&
                         pi->frames_sent == 0) {
@@ -4066,9 +4044,7 @@ static inline void l2cap_data_channel_rrframe(struct sock *sk, u16 rx_control)
                 if (pi->conn_state & L2CAP_CONN_SREJ_SENT) {
                         l2cap_send_ack(pi);
                 } else {
-                        spin_lock_bh(&pi->send_lock);
                         l2cap_ertm_send(sk);
-                        spin_unlock_bh(&pi->send_lock);
                 }
         }
 }
@@ -4113,9 +4089,7 @@ static inline void l2cap_data_channel_srejframe(struct sock *sk, u16 rx_control)
                 pi->conn_state |= L2CAP_CONN_SEND_FBIT;
                 l2cap_retransmit_one_frame(sk, tx_seq);
 
-                spin_lock_bh(&pi->send_lock);
                 l2cap_ertm_send(sk);
-                spin_unlock_bh(&pi->send_lock);
 
                 if (pi->conn_state & L2CAP_CONN_WAIT_F) {
                         pi->srej_save_reqseq = tx_seq;