Messages in this thread Patch in this message | | | Date | Fri, 08 Jun 2007 00:22:21 -0700 | From | Chris Wright <> | Subject | [patch 54/54] BLUETOOTH: Fix locking in hci_sock_dev_event(). |
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-stable review patch. If anyone has any objections, please let us know. ---------------------
From: Satyam Sharma <ssatyam@cse.iitk.ac.in>
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> --- net/bluetooth/hci_sock.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- linux-2.6.21.4.orig/net/bluetooth/hci_sock.c +++ linux-2.6.21.4/net/bluetooth/hci_sock.c @@ -656,7 +656,8 @@ 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; @@ -665,7 +666,8 @@ 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); } -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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