From: "Gustavo F. Padovan" <padovan@xxxxxxxxxxxxxx>
This list has much more reads than writes, so RCU makes senses here, also
it avoid deadlock against the socket lock.
Signed-off-by: Gustavo F. Padovan <padovan@xxxxxxxxxxxxxx>
---
net/bluetooth/l2cap_core.c | 117 +++++++++++++++++++++----------------------
1 files changed, 57 insertions(+), 60 deletions(-)
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index d616519..a212295 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;
+ }
}
+
+ rcu_read_unlock();
return NULL;
}
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;
}
--
1.7.6.4
--
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