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[BLUETOOTH]: Fix locking in hci_sock_dev_event().

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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>
This commit is contained in:
Satyam Sharma 2007-05-16 23:50:16 -07:00 committed by David S. Miller
parent 689d79469b
commit 4ce61d1c7a
1 changed files with 4 additions and 2 deletions
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6
net/bluetooth/hci_sock.c
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@ -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);
}