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authorSatyam Sharma <ssatyam@cse.iitk.ac.in>2007-05-16 23:50:16 -0700
committerDavid S. Miller <davem@sunset.davemloft.net>2007-05-17 14:20:30 -0700
commit4ce61d1c7a8ef4c1337fa983a3036d4010e3c19e (patch)
treee7bf734478bc3f726d883439d5fdc44699d9a20a
parent689d79469b64662440a93ffbd1cbf994510bcbf6 (diff)
[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 <ssatyam@cse.iitk.ac.in> Signed-off-by: Marcel Holtmann <marcel@holtmann.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/bluetooth/hci_sock.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index bfc9a35bad3..1dae3dfc66a 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -665,7 +665,8 @@ 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;
@@ -674,7 +675,8 @@ 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);
}