From 3d57dc6806599ca7d389fc9410eefbc1a7dc32bc Mon Sep 17 00:00:00 2001 From: "Gustavo F. Padovan" Date: Sat, 17 Dec 2011 10:56:45 -0200 Subject: [PATCH] Bluetooth: Change l2cap chan_list to use RCU This list has much more reads than writes, so RCU makes senses here, also it avoid deadlock against the socket lock. Acked-by: Marcel Holtmann Signed-off-by: Gustavo F. Padovan --- net/bluetooth/l2cap_core.c | 119 ++++++++++++++++++------------------- 1 file changed, 58 insertions(+), 61 deletions(-) diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index d6165199fc8b..a1766adee397 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -89,24 +89,36 @@ static inline void chan_put(struct l2cap_chan *c) static struct l2cap_chan *__l2cap_get_chan_by_dcid(struct l2cap_conn *conn, u16 cid) { - struct l2cap_chan *c; + struct l2cap_chan *c, *r = NULL; - list_for_each_entry(c, &conn->chan_l, list) { - if (c->dcid == cid) - return c; + rcu_read_lock(); + + list_for_each_entry_rcu(c, &conn->chan_l, list) { + if (c->dcid == cid) { + r = c; + break; + } } - return NULL; + + rcu_read_unlock(); + return r; } static struct l2cap_chan *__l2cap_get_chan_by_scid(struct l2cap_conn *conn, u16 cid) { - struct l2cap_chan *c; + struct l2cap_chan *c, *r = NULL; - list_for_each_entry(c, &conn->chan_l, list) { - if (c->scid == cid) - return c; + rcu_read_lock(); + + list_for_each_entry_rcu(c, &conn->chan_l, list) { + if (c->scid == cid) { + r = c; + break; + } } - return NULL; + + rcu_read_unlock(); + return r; } /* Find channel with given SCID. @@ -115,34 +127,36 @@ 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; + struct l2cap_chan *c, *r = NULL; - list_for_each_entry(c, &conn->chan_l, list) { - if (c->ident == ident) - return c; + rcu_read_lock(); + + list_for_each_entry_rcu(c, &conn->chan_l, list) { + if (c->ident == ident) { + r = c; + break; + } } - return NULL; + + rcu_read_unlock(); + return r; } 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; } @@ -323,7 +337,7 @@ void l2cap_chan_destroy(struct l2cap_chan *chan) chan_put(chan); } -static void __l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan) +static void l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan) { BT_DBG("conn %p, psm 0x%2.2x, dcid 0x%4.4x", conn, chan->psm, chan->dcid); @@ -364,7 +378,7 @@ static void __l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan) chan_hold(chan); - list_add(&chan->list, &conn->chan_l); + list_add_rcu(&chan->list, &conn->chan_l); } /* Delete channel. @@ -381,9 +395,9 @@ static void l2cap_chan_del(struct l2cap_chan *chan, int err) if (conn) { /* Delete from channel list */ - mutex_lock(&conn->chan_lock); - list_del(&chan->list); - mutex_unlock(&conn->chan_lock); + list_del_rcu(&chan->list); + synchronize_rcu(); + chan_put(chan); chan->conn = NULL; @@ -750,13 +764,13 @@ 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, *tmp; + struct l2cap_chan *chan; BT_DBG("conn %p", conn); - mutex_lock(&conn->chan_lock); + rcu_read_lock(); - list_for_each_entry_safe(chan, tmp, &conn->chan_l, list) { + list_for_each_entry_rcu(chan, &conn->chan_l, list) { struct sock *sk = chan->sk; bh_lock_sock(sk); @@ -780,9 +794,7 @@ static void l2cap_conn_start(struct l2cap_conn *conn) &chan->conf_state)) { /* l2cap_chan_close() calls list_del(chan) * so release the lock */ - mutex_unlock(&conn->chan_lock); l2cap_chan_close(chan, ECONNRESET); - utex_lock(&conn->chan_lock); bh_unlock_sock(sk); continue; } @@ -838,7 +850,7 @@ static void l2cap_conn_start(struct l2cap_conn *conn) bh_unlock_sock(sk); } - mutex_unlock(&conn->chan_lock); + rcu_read_unlock(); } /* Find socket with cid and source bdaddr. @@ -903,8 +915,6 @@ static void l2cap_le_conn_ready(struct l2cap_conn *conn) sk = chan->sk; - mutex_lock(&conn->chan_lock); - hci_conn_hold(conn->hcon); bacpy(&bt_sk(sk)->src, conn->src); @@ -912,15 +922,13 @@ static void l2cap_le_conn_ready(struct l2cap_conn *conn) bt_accept_enqueue(parent, sk); - __l2cap_chan_add(conn, chan); + l2cap_chan_add(conn, chan); __set_chan_timer(chan, sk->sk_sndtimeo); l2cap_state_change(chan, BT_CONNECTED); parent->sk_data_ready(parent, 0); - mutex_unlock(&conn->chan_lock); - clean: release_sock(parent); } @@ -954,9 +962,9 @@ 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); - mutex_lock(&conn->chan_lock); + rcu_read_lock(); - list_for_each_entry(chan, &conn->chan_l, list) { + list_for_each_entry_rcu(chan, &conn->chan_l, list) { struct sock *sk = chan->sk; bh_lock_sock(sk); @@ -976,7 +984,7 @@ static void l2cap_conn_ready(struct l2cap_conn *conn) bh_unlock_sock(sk); } - mutex_unlock(&conn->chan_lock); + rcu_read_unlock(); } /* Notify sockets that we cannot guaranty reliability anymore */ @@ -986,16 +994,16 @@ static void l2cap_conn_unreliable(struct l2cap_conn *conn, int err) BT_DBG("conn %p", conn); - mutex_lock(&conn->chan_lock); + rcu_read_lock(); - list_for_each_entry(chan, &conn->chan_l, list) { + list_for_each_entry_rcu(chan, &conn->chan_l, list) { struct sock *sk = chan->sk; if (test_bit(FLAG_FORCE_RELIABLE, &chan->flags)) sk->sk_err = err; } - mutex_unlock(&conn->chan_lock); + rcu_read_unlock(); } static void l2cap_info_timeout(struct work_struct *work) @@ -1087,7 +1095,6 @@ 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); @@ -1102,13 +1109,6 @@ static struct l2cap_conn *l2cap_conn_add(struct hci_conn *hcon, u8 status) return conn; } -static inline void l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan) -{ - mutex_lock(&conn->chan_lock); - __l2cap_chan_add(conn, chan); - mutex_unlock(&conn->chan_lock); -} - /* ---- Socket interface ---- */ /* Find socket with psm and source bdaddr. @@ -1825,8 +1825,9 @@ static void l2cap_raw_recv(struct l2cap_conn *conn, struct sk_buff *skb) BT_DBG("conn %p", conn); - mutex_lock(&conn->chan_lock); - list_for_each_entry(chan, &conn->chan_l, list) { + rcu_read_lock(); + + list_for_each_entry_rcu(chan, &conn->chan_l, list) { struct sock *sk = chan->sk; if (chan->chan_type != L2CAP_CHAN_RAW) continue; @@ -1841,7 +1842,8 @@ static void l2cap_raw_recv(struct l2cap_conn *conn, struct sk_buff *skb) if (chan->ops->recv(chan->data, nskb)) kfree_skb(nskb); } - mutex_unlock(&conn->chan_lock); + + rcu_read_unlock(); } /* ---- L2CAP signalling commands ---- */ @@ -2641,11 +2643,8 @@ static inline int l2cap_connect_req(struct l2cap_conn *conn, struct l2cap_cmd_hd sk = chan->sk; - mutex_lock(&conn->chan_lock); - /* Check if we already have channel with that dcid */ if (__l2cap_get_chan_by_dcid(conn, scid)) { - mutex_unlock(&conn->chan_lock); sock_set_flag(sk, SOCK_ZAPPED); chan->ops->close(chan->data); goto response; @@ -2660,7 +2659,7 @@ static inline int l2cap_connect_req(struct l2cap_conn *conn, struct l2cap_cmd_hd bt_accept_enqueue(parent, sk); - __l2cap_chan_add(conn, chan); + l2cap_chan_add(conn, chan); dcid = chan->scid; @@ -2691,8 +2690,6 @@ static inline int l2cap_connect_req(struct l2cap_conn *conn, struct l2cap_cmd_hd status = L2CAP_CS_NO_INFO; } - mutex_unlock(&conn->chan_lock); - response: release_sock(parent); @@ -4528,9 +4525,9 @@ static int l2cap_security_cfm(struct hci_conn *hcon, u8 status, u8 encrypt) del_timer(&conn->security_timer); } - mutex_lock(&conn->chan_lock); + rcu_read_lock(); - list_for_each_entry(chan, &conn->chan_l, list) { + list_for_each_entry_rcu(chan, &conn->chan_l, list) { struct sock *sk = chan->sk; bh_lock_sock(sk); @@ -4608,7 +4605,7 @@ static int l2cap_security_cfm(struct hci_conn *hcon, u8 status, u8 encrypt) bh_unlock_sock(sk); } - mutex_unlock(&conn->chan_lock); + rcu_read_unlock(); return 0; } -- 2.30.2