[PATCH v4] Bluetooth: silence lockdep warning

* [PATCH v4] Bluetooth: silence lockdep warning
@ 2012-01-21 22:28 Octavian Purdila
  2012-01-22  9:21 ` Marcel Holtmann
  0 siblings, 1 reply; 3+ messages in thread
From: Octavian Purdila @ 2012-01-21 22:28 UTC (permalink / raw)
  To: linux-bluetooth; +Cc: kirill.shutemov, Octavian Purdila

Since bluetooth uses multiple protocols types, to avoid lockdep
warnings, we need to use different lockdep classes (one for each
protocol type).

This is already done in bt_sock_create but it misses a couple of cases
when new connections are created. This patch corrects that to fix the
following warning:

<4>[ 1864.732366] =======================================================
<4>[ 1864.733030] [ INFO: possible circular locking dependency detected ]
<4>[ 1864.733544] 3.0.16-mid3-00007-gc9a0f62 #3
<4>[ 1864.733883] -------------------------------------------------------
<4>[ 1864.734408] t.android.btclc/4204 is trying to acquire lock:
<4>[ 1864.734869]  (rfcomm_mutex){+.+.+.}, at: [<c14970ea>] rfcomm_dlc_close+0x15/0x30
<4>[ 1864.735541]
<4>[ 1864.735549] but task is already holding lock:
<4>[ 1864.736045]  (sk_lock-AF_BLUETOOTH){+.+.+.}, at: [<c1498bf7>] lock_sock+0xa/0xc
<4>[ 1864.736732]
<4>[ 1864.736740] which lock already depends on the new lock.
<4>[ 1864.736750]
<4>[ 1864.737428]
<4>[ 1864.737437] the existing dependency chain (in reverse order) is:
<4>[ 1864.738016]
<4>[ 1864.738023] -> #1 (sk_lock-AF_BLUETOOTH){+.+.+.}:
<4>[ 1864.738549]        [<c1062273>] lock_acquire+0x104/0x140
<4>[ 1864.738977]        [<c13d35c1>] lock_sock_nested+0x58/0x68
<4>[ 1864.739411]        [<c1493c33>] l2cap_sock_sendmsg+0x3e/0x76
<4>[ 1864.739858]        [<c13d06c3>] __sock_sendmsg+0x50/0x59
<4>[ 1864.740279]        [<c13d0ea2>] sock_sendmsg+0x94/0xa8
<4>[ 1864.740687]        [<c13d0ede>] kernel_sendmsg+0x28/0x37
<4>[ 1864.741106]        [<c14969ca>] rfcomm_send_frame+0x30/0x38
<4>[ 1864.741542]        [<c1496a2a>] rfcomm_send_ua+0x58/0x5a
<4>[ 1864.741959]        [<c1498447>] rfcomm_run+0x441/0xb52
<4>[ 1864.742365]        [<c104f095>] kthread+0x63/0x68
<4>[ 1864.742742]        [<c14d5182>] kernel_thread_helper+0x6/0xd
<4>[ 1864.743187]
<4>[ 1864.743193] -> #0 (rfcomm_mutex){+.+.+.}:
<4>[ 1864.743667]        [<c1061ada>] __lock_acquire+0x988/0xc00
<4>[ 1864.744100]        [<c1062273>] lock_acquire+0x104/0x140
<4>[ 1864.744519]        [<c14d2c70>] __mutex_lock_common+0x3b/0x33f
<4>[ 1864.744975]        [<c14d303e>] mutex_lock_nested+0x2d/0x36
<4>[ 1864.745412]        [<c14970ea>] rfcomm_dlc_close+0x15/0x30
<4>[ 1864.745842]        [<c14990d9>] __rfcomm_sock_close+0x5f/0x6b
<4>[ 1864.746288]        [<c1499114>] rfcomm_sock_shutdown+0x2f/0x62
<4>[ 1864.746737]        [<c13d275d>] sys_socketcall+0x1db/0x422
<4>[ 1864.747165]        [<c14d42f0>] syscall_call+0x7/0xb

Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
---
 include/net/bluetooth/bluetooth.h |    2 ++
 net/bluetooth/af_bluetooth.c      |   12 +++++-------
 net/bluetooth/l2cap_sock.c        |    2 ++
 net/bluetooth/rfcomm/sock.c       |    2 ++
 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
index abaad6e..4a82ca0 100644
--- a/include/net/bluetooth/bluetooth.h
+++ b/include/net/bluetooth/bluetooth.h
@@ -256,4 +256,6 @@ void l2cap_exit(void);
 int sco_init(void);
 void sco_exit(void);
 
+void bt_sock_reclassify_lock(struct sock *sk, int proto);
+
 #endif /* __BLUETOOTH_H */
diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
index ef92864..72eb187 100644
--- a/net/bluetooth/af_bluetooth.c
+++ b/net/bluetooth/af_bluetooth.c
@@ -71,19 +71,16 @@ static const char *const bt_slock_key_strings[BT_MAX_PROTO] = {
 	"slock-AF_BLUETOOTH-BTPROTO_AVDTP",
 };
 
-static inline void bt_sock_reclassify_lock(struct socket *sock, int proto)
+void bt_sock_reclassify_lock(struct sock *sk, int proto)
 {
-	struct sock *sk = sock->sk;
-
-	if (!sk)
-		return;
-
+	BUG_ON(!sk);
 	BUG_ON(sock_owned_by_user(sk));
 
 	sock_lock_init_class_and_name(sk,
 			bt_slock_key_strings[proto], &bt_slock_key[proto],
 				bt_key_strings[proto], &bt_lock_key[proto]);
 }
+EXPORT_SYMBOL(bt_sock_reclassify_lock);
 
 int bt_sock_register(int proto, const struct net_proto_family *ops)
 {
@@ -145,7 +142,8 @@ static int bt_sock_create(struct net *net, struct socket *sock, int proto,
 
 	if (bt_proto[proto] && try_module_get(bt_proto[proto]->owner)) {
 		err = bt_proto[proto]->create(net, sock, proto, kern);
-		bt_sock_reclassify_lock(sock, proto);
+		if (!err)
+			bt_sock_reclassify_lock(sock->sk, proto);
 		module_put(bt_proto[proto]->owner);
 	}
 
diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index c61d967..46b22d9 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -849,6 +849,8 @@ static struct l2cap_chan *l2cap_sock_new_connection_cb(void *data)
 	if (!sk)
 		return NULL;
 
+	bt_sock_reclassify_lock(sk, BTPROTO_L2CAP);
+
 	l2cap_sock_init(sk, parent);
 
 	return l2cap_pi(sk)->chan;
diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
index f066678..22169c3 100644
--- a/net/bluetooth/rfcomm/sock.c
+++ b/net/bluetooth/rfcomm/sock.c
@@ -956,6 +956,8 @@ int rfcomm_connect_ind(struct rfcomm_session *s, u8 channel, struct rfcomm_dlc *
 	if (!sk)
 		goto done;
 
+	bt_sock_reclassify_lock(sk, BTPROTO_RFCOMM);
+
 	rfcomm_sock_init(sk, parent);
 	bacpy(&bt_sk(sk)->src, &src);
 	bacpy(&bt_sk(sk)->dst, &dst);
-- 
1.7.1


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