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authorJohan Hedberg <johan.hedberg@intel.com>2014-11-12 23:22:21 +0300
committerMarcel Holtmann <marcel@holtmann.org>2014-11-13 09:49:09 +0300
commitabe84903a8efc6b83fa92161429e0e3a28bde15c (patch)
tree3b1b90b1c170c41bbd6fcdae92e8726024c37ade /net/bluetooth
parent24ccb9f4f7a3a5a867bbc880019cdb4b41176b63 (diff)
downloadlinux-abe84903a8efc6b83fa92161429e0e3a28bde15c.tar.xz
Bluetooth: Use proper nesting annotation for l2cap_chan lock
By default lockdep considers all L2CAP channels equal. This would mean that we get warnings if a channel is locked when another one's lock is tried to be acquired in the same thread. This kind of inter-channel locking dependencies exist in the form of parent-child channels as well as any channel wishing to elevate the security by requesting procedures on the SMP channel. To eliminate the chance for these lockdep warnings we introduce a nesting level for each channel and use that when acquiring the channel lock. For now there exists the earlier mentioned three identified categories: SMP, "normal" channels and parent channels (i.e. those in BT_LISTEN state). The nesting level is defined as atomic_t since we need access to it before the lock is actually acquired. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Diffstat (limited to 'net/bluetooth')
-rw-r--r--net/bluetooth/l2cap_sock.c9
-rw-r--r--net/bluetooth/smp.c10
2 files changed, 19 insertions, 0 deletions
diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index ad1cf82fee02..f1a51564b8fd 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -285,6 +285,12 @@ static int l2cap_sock_listen(struct socket *sock, int backlog)
sk->sk_max_ack_backlog = backlog;
sk->sk_ack_backlog = 0;
+ /* Listening channels need to use nested locking in order not to
+ * cause lockdep warnings when the created child channels end up
+ * being locked in the same thread as the parent channel.
+ */
+ atomic_set(&chan->nesting, L2CAP_NESTING_PARENT);
+
chan->state = BT_LISTEN;
sk->sk_state = BT_LISTEN;
@@ -1497,6 +1503,9 @@ static void l2cap_sock_init(struct sock *sk, struct sock *parent)
l2cap_chan_set_defaults(chan);
}
+ /* Set default lock nesting level */
+ atomic_set(&chan->nesting, L2CAP_NESTING_NORMAL);
+
/* Default config options */
chan->flush_to = L2CAP_DEFAULT_FLUSH_TO;
diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index 3d38553eb526..3b63c7f09dd5 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -1658,6 +1658,13 @@ static inline struct l2cap_chan *smp_new_conn_cb(struct l2cap_chan *pchan)
chan->omtu = pchan->omtu;
chan->mode = pchan->mode;
+ /* Other L2CAP channels may request SMP routines in order to
+ * change the security level. This means that the SMP channel
+ * lock must be considered in its own category to avoid lockdep
+ * warnings.
+ */
+ atomic_set(&chan->nesting, L2CAP_NESTING_SMP);
+
BT_DBG("created chan %p", chan);
return chan;
@@ -1715,6 +1722,9 @@ int smp_register(struct hci_dev *hdev)
chan->imtu = L2CAP_DEFAULT_MTU;
chan->ops = &smp_root_chan_ops;
+ /* Set correct nesting level for a parent/listening channel */
+ atomic_set(&chan->nesting, L2CAP_NESTING_PARENT);
+
hdev->smp_data = chan;
return 0;