[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().
Cc: David Miller <[email protected]>
Signed-off-by: Satyam Sharma <[email protected]>
Signed-off-by: Marcel Holtmann <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>
---
net/bluetooth/hci_sock.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
---
diff -ruNp a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
--- a/net/bluetooth/hci_sock.c 2007-05-16 17:31:06.000000000 +0530
+++ b/net/bluetooth/hci_sock.c 2007-05-16 17:38:35.000000000 +0530
@@ -665,7 +665,8 @@ static int hci_sock_dev_event(struct not
/* 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 not
hci_dev_put(hdev);
}
- release_sock(sk);
+ bh_unlock_sock(sk);
+ local_bh_enable();
}
read_unlock(&hci_sk_list.lock);
}
-
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