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Commit 3d57dc68 authored by Gustavo Padovan's avatar Gustavo Padovan
Browse files

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: default avatarMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: default avatarGustavo F. Padovan <padovan@profusion.mobi>
parent 03a00194
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+58 −61
Original line number Diff line number Diff line
@@ -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;
}