From: Satyam Sharma Date: Thu, 7 Jun 2007 06:02:16 +0000 (-0700) Subject: [PATCH] BLUETOOTH: Fix locking in hci_sock_dev_event(). X-Git-Tag: v2.6.21.5~1 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d951c856912acfbb85eb33f59230c3019ef5dd55;p=thirdparty%2Fkernel%2Fstable.git [PATCH] BLUETOOTH: Fix locking in hci_sock_dev_event(). We presently use lock_sock() to acquire a lock on a socket in hci_sock_dev_event(), but this goes BUG because lock_sock() can sleep and we're already holding a read-write spinlock at that point. So, we must use the non-sleeping BH version, bh_lock_sock(). However, hci_sock_dev_event() is called from user context and hence using simply bh_lock_sock() will deadlock against a concurrent softirq that tries to acquire a lock on the same socket. Hence, disabling BH's before acquiring the socket lock and enable them afterwards, is the proper solution to fix socket locking in hci_sock_dev_event(). Signed-off-by: Satyam Sharma Signed-off-by: Marcel Holtmann Signed-off-by: Jiri Kosina Signed-off-by: David S. Miller Signed-off-by: Chris Wright Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c index 71f5cfbbebb83..2f6e1ea6a5cc1 100644 --- a/net/bluetooth/hci_sock.c +++ b/net/bluetooth/hci_sock.c @@ -656,7 +656,8 @@ static int hci_sock_dev_event(struct notifier_block *this, unsigned long event, /* Detach sockets from device */ read_lock(&hci_sk_list.lock); sk_for_each(sk, node, &hci_sk_list.head) { - lock_sock(sk); + local_bh_disable(); + bh_lock_sock_nested(sk); if (hci_pi(sk)->hdev == hdev) { hci_pi(sk)->hdev = NULL; sk->sk_err = EPIPE; @@ -665,7 +666,8 @@ static int hci_sock_dev_event(struct notifier_block *this, unsigned long event, hci_dev_put(hdev); } - release_sock(sk); + bh_unlock_sock(sk); + local_bh_enable(); } read_unlock(&hci_sk_list.lock); }