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authorSatyam Sharma <ssatyam@cse.iitk.ac.in>2007-06-06 23:02:16 -0700
committerChris Wright <chrisw@sous-sol.org>2007-06-11 11:36:54 -0700
commitd951c856912acfbb85eb33f59230c3019ef5dd55 (patch)
tree504bca3dfe564fd37ab772dfc52e0d675bef2e5a
parent02a074766a0a8d1afd26f476b73422c08e34cbc8 (diff)
[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 <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> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-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 71f5cfbbebb8..2f6e1ea6a5cc 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);
}