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@ 2008-04-01  8:59 Dave Young
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From: Dave Young @ 2008-04-01  8:59 UTC (permalink / raw)
  To: David Miller; +Cc: davej, netdev, linux-bluetooth, linux-kernel

marcel@holtmann.org
Bcc: 
Subject: Re: bluetooth lockdep trace. (.25rc5-git4)
Reply-To: 
In-Reply-To: <20080328.182021.46780895.davem@davemloft.net>

On Fri, Mar 28, 2008 at 06:20:21PM -0700, David Miller wrote:
> From: Dave Jones <davej@codemonkey.org.uk>
> Date: Thu, 27 Mar 2008 12:21:56 -0400
> 
> > Mar 27 08:10:57 localhost kernel: Pid: 3611, comm: obex-data-serve Not tainted 2.6.25-0.121.rc5.git4.fc9 #1
> > Mar 27 08:10:57 localhost kernel:  [__lock_acquire+2287/3089] __lock_acquire+0x8ef/0xc11
> > Mar 27 08:10:57 localhost kernel:  [sched_clock+8/11] ? sched_clock+0x8/0xb
> > Mar 27 08:10:57 localhost kernel:  [lock_acquire+106/144] lock_acquire+0x6a/0x90
> > Mar 27 08:10:57 localhost kernel:  [<f8bd9321>] ? l2cap_sock_bind+0x29/0x108 [l2cap]
> > Mar 27 08:10:57 localhost kernel:  [lock_sock_nested+182/198] lock_sock_nested+0xb6/0xc6
> > Mar 27 08:10:57 localhost kernel:  [<f8bd9321>] ? l2cap_sock_bind+0x29/0x108 [l2cap]
> > Mar 27 08:10:57 localhost kernel:  [security_socket_post_create+22/27] ? security_socket_post_create+0x16/0x1b
> > Mar 27 08:10:57 localhost kernel:  [__sock_create+388/472] ? __sock_create+0x184/0x1d8
> > Mar 27 08:10:57 localhost kernel:  [<f8bd9321>] l2cap_sock_bind+0x29/0x108 [l2cap]
> > Mar 27 08:10:57 localhost kernel:  [kernel_bind+10/13] kernel_bind+0xa/0xd
> > Mar 27 08:10:57 localhost kernel:  [<f8dad3d7>] rfcomm_dlc_open+0xc8/0x294 [rfcomm]
> > Mar 27 08:10:57 localhost kernel:  [lock_sock_nested+187/198] ? lock_sock_nested+0xbb/0xc6
> > Mar 27 08:10:57 localhost kernel:  [<f8dae18c>] rfcomm_sock_connect+0x8b/0xc2 [rfcomm]
> > Mar 27 08:10:57 localhost kernel:  [sys_connect+96/125] sys_connect+0x60/0x7d
> > Mar 27 08:10:57 localhost kernel:  [__lock_acquire+1370/3089] ? __lock_acquire+0x55a/0xc11
> > Mar 27 08:10:57 localhost kernel:  [sys_socketcall+140/392] sys_socketcall+0x8c/0x188
> > Mar 27 08:10:57 localhost kernel:  [syscall_call+7/11] syscall_call+0x7/0xb
> 
> rfcomm connect locks the socket, then does rfcomm_dlc_open which in
> turn can do a l2cap_sock_bind on a seperate second socket which in
> turn locks that second socket.
> 
> Both of these sockets are AF_BLUETOOTH family, so lockdep thinks there
> is a locking conflict, even though what is happening here is perfectly
> fine since the two sockets are totally different AF_BLUETOOTH
> sub-types.
> 
> Bluetooth will need to use sock_lock_init_class_and_name() and
> lock sub-classes per AF_BLUETOOTH socket sub-type.
> 
> David, could you or someone else work on this?

Does this fix the problem?

---
'rfcomm connect' will trigger lockdep warnings which is caused by
locking diffrent kinds of bluetooth sockets at the same time.

So using sub-classes per AF_BLUETOOTH sub-type for lockdep.

Thanks for the hints from dave jones.


Signed-off-by: Dave Young <hidave.darkstar@gmail.com>

---
net/bluetooth/af_bluetooth.c |   40 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)

diff -upr linux/net/bluetooth/af_bluetooth.c linux.new/net/bluetooth/af_bluetooth.c
--- linux/net/bluetooth/af_bluetooth.c	2008-04-01 16:09:17.000000000 +0800
+++ linux.new/net/bluetooth/af_bluetooth.c	2008-04-01 16:08:52.000000000 +0800
@@ -53,6 +53,30 @@
 /* Bluetooth sockets */
 #define BT_MAX_PROTO	8
 static struct net_proto_family *bt_proto[BT_MAX_PROTO];
+
+static struct lock_class_key bt_slock_key[BT_MAX_PROTO];
+static struct lock_class_key bt_lock_key[BT_MAX_PROTO];
+static const char *bt_key_strings[BT_MAX_PROTO] = {
+	"sk_lock-AF_BLUETOOTH-BTPROTO_L2CAP",
+	"sk_lock-AF_BLUETOOTH-BTPROTO_HCI",
+	"sk_lock-AF_BLUETOOTH-BTPROTO_SCO",
+	"sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM",
+	"sk_lock-AF_BLUETOOTH-BTPROTO_BNEP",
+	"sk_lock-AF_BLUETOOTH-BTPROTO_CMTP",
+	"sk_lock-AF_BLUETOOTH-BTPROTO_HIDP",
+	"sk_lock-AF_BLUETOOTH-BTPROTO_AVDTP",
+};
+
+static const char *bt_slock_key_strings[BT_MAX_PROTO] = {
+	"slock-AF_BLUETOOTH-BTPROTO_L2CAP",
+	"slock-AF_BLUETOOTH-BTPROTO_HCI",
+	"slock-AF_BLUETOOTH-BTPROTO_SCO",
+	"slock-AF_BLUETOOTH-BTPROTO_RFCOMM",
+	"slock-AF_BLUETOOTH-BTPROTO_BNEP",
+	"slock-AF_BLUETOOTH-BTPROTO_CMTP",
+	"slock-AF_BLUETOOTH-BTPROTO_HIDP",
+	"slock-AF_BLUETOOTH-BTPROTO_AVDTP",
+};
 static DEFINE_RWLOCK(bt_proto_lock);
 
 int bt_sock_register(int proto, struct net_proto_family *ops)
@@ -95,6 +119,21 @@ int bt_sock_unregister(int proto)
 }
 EXPORT_SYMBOL(bt_sock_unregister);
 
+static void bt_reclassify_sock_lock(struct socket *sock, int proto)
+{
+	struct sock *sk = sock->sk;
+
+	if (!sk)
+		return;
+	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]);
+}
+
 static int bt_sock_create(struct net *net, struct socket *sock, int proto)
 {
 	int err;
@@ -117,6 +156,7 @@ static int bt_sock_create(struct net *ne
 
 	if (bt_proto[proto] && try_module_get(bt_proto[proto]->owner)) {
 		err = bt_proto[proto]->create(net, sock, proto);
+		bt_reclassify_sock_lock(sock, proto);
 		module_put(bt_proto[proto]->owner);
 	}
 

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