Bluetooth: Fix nested sleeps

l2cap/rfcomm/sco_sock_accept() are wait loops which may acquire
sleeping locks. Since both wait loops and sleeping locks use
task_struct.state to sleep and wake, the nested sleeping locks
destroy the wait loop state.

Use the newly-minted wait_woken() and DEFINE_WAIT_FUNC() for the
wait loop. DEFINE_WAIT_FUNC() allows an alternate wake function
to be specified; in this case, the predefined scheduler function,
woken_wake_function(). This wait construct ensures wakeups will
not be missed without requiring the wait loop to set the
task state before condition evaluation. How this works:

 CPU 0                            |  CPU 1
                                  |
                                  | is <condition> set?
                                  | no
set <condition>                   |
                                  |
wake_up_interruptible             |
  woken_wake_function             |
    set WQ_FLAG_WOKEN             |
    try_to_wake_up                |
                                  | wait_woken
                                  |   set TASK_INTERRUPTIBLE
                                  |   WQ_FLAG_WOKEN? yes
                                  |   set TASK_RUNNING
                                  |
                                  | - loop -
				  |
				  | is <condition> set?
                                  | yes - exit wait loop

Fixes "do not call blocking ops when !TASK_RUNNING" warnings
in l2cap_sock_accept(), rfcomm_sock_accept() and sco_sock_accept().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

1 files changed, 4 insertions, 5 deletions

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 20206cd3acbc..60694f0f4c73 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -302,7 +302,7 @@ done:
 static int l2cap_sock_accept(struct socket *sock, struct socket *newsock,
                              int flags)
 {
-        DECLARE_WAITQUEUE(wait, current);
+        DEFINE_WAIT_FUNC(wait, woken_wake_function);
         struct sock *sk = sock->sk, *nsk;
         long timeo;
         int err = 0;
@@ -316,8 +316,6 @@ static int l2cap_sock_accept(struct socket *sock, struct socket *newsock,
         /* Wait for an incoming connection. (wake-one). */
         add_wait_queue_exclusive(sk_sleep(sk), &wait);
         while (1) {
-                set_current_state(TASK_INTERRUPTIBLE);
-
                 if (sk->sk_state != BT_LISTEN) {
                         err = -EBADFD;
                         break;
@@ -338,10 +336,11 @@ static int l2cap_sock_accept(struct socket *sock, struct socket *newsock,
                 }
 
                 release_sock(sk);
-                timeo = schedule_timeout(timeo);
+
+                timeo = wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
+
                 lock_sock_nested(sk, L2CAP_NESTING_PARENT);
         }
-        __set_current_state(TASK_RUNNING);
         remove_wait_queue(sk_sleep(sk), &wait);
 
         if (err)