Return-Path: Date: Mon, 20 Feb 2012 16:33:57 -0200 From: Gustavo Padovan To: Emeltchenko Andrei Cc: linux-bluetooth@vger.kernel.org Subject: Re: [RFCv6 02/14] Bluetooth: Revert to mutexes from RCU list Message-ID: <20120220165334.GB28852@joana> References: <1329747685-4163-1-git-send-email-Andrei.Emeltchenko.news@gmail.com> <1329747685-4163-3-git-send-email-Andrei.Emeltchenko.news@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1329747685-4163-3-git-send-email-Andrei.Emeltchenko.news@gmail.com> Sender: linux-bluetooth-owner@vger.kernel.org List-ID: Hi Andrei, * Emeltchenko Andrei [2012-02-20 16:21:13 +0200]: > From: Andrei Emeltchenko > > Usage of RCU list looks not reasonalbe for a number of reasons: > our code sleep and we have to use socket spinlocks, some parts > of code are updaters thus we need to use mutexes anyway. > > Signed-off-by: Andrei Emeltchenko > --- > net/bluetooth/l2cap_core.c | 165 ++++++++++++++++++++++++++------------------ > net/bluetooth/l2cap_sock.c | 10 +++ > 2 files changed, 108 insertions(+), 67 deletions(-) > > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c > index 63539f9..90e29ac 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 +2768,10 @@ static inline int l2cap_connect_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hd > } > > release_sock(sk); > - return 0; add an extra blank line here please. > +unlock: > + mutex_unlock(&conn->chan_lock); > + > + return err; > } > > static inline void set_default_fcs(struct l2cap_chan *chan) > @@ -2793,6 +2804,7 @@ 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 +2917,7 @@ 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 +3019,16 @@ 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; Seems to me we can use l2cap_get_chan_by_scid() here. > + } > > sk = chan->sk; > + lock_sock(sk); > > rsp.dcid = cpu_to_le16(chan->scid); > rsp.scid = cpu_to_le16(chan->dcid); > @@ -3022,6 +3040,9 @@ 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 +3058,24 @@ 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; Same here. Gustavo