Bluetooth: cmtp: fix possible might sleep error in cmtp_session

commit f06d977309d09253c744e54e75c5295ecc52b7b4 upstream.

It looks like cmtp_session has same pattern as the issue reported in
old rfcomm:

	while (1) {
		set_current_state(TASK_INTERRUPTIBLE);
		if (condition)
			break;
		// may call might_sleep here
		schedule();
	}
	__set_current_state(TASK_RUNNING);

Which fixed at:
	dfb2fae Bluetooth: Fix nested sleeps

So let's fix it at the same way, also follow the suggestion of:
https://lwn.net/Articles/628628/

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: AL Yu-Chen Cho <acho@suse.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/bluetooth/cmtp/core.c b/net/bluetooth/cmtp/core.c
index 298ed37..3a39fd5 100644 (file)
--- a/net/bluetooth/cmtp/core.c
+++ b/net/bluetooth/cmtp/core.c
@@ -281,16 +281,16 @@ static int cmtp_session(void *arg)
        struct cmtp_session *session = arg;
        struct sock *sk = session->sock->sk;
        struct sk_buff *skb;
-       wait_queue_t wait;
+       DEFINE_WAIT_FUNC(wait, woken_wake_function);
 
        BT_DBG("session %p", session);
 
        set_user_nice(current, -15);
 
-       init_waitqueue_entry(&wait, current);
        add_wait_queue(sk_sleep(sk), &wait);
        while (1) {
-               set_current_state(TASK_INTERRUPTIBLE);
+               /* Ensure session->terminate is updated */
+               smp_mb__before_atomic();
 
                if (atomic_read(&session->terminate))
                        break;
@@ -307,9 +307,8 @@ static int cmtp_session(void *arg)
 
                cmtp_process_transmit(session);
 
-               schedule();
+               wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
        }
-       __set_current_state(TASK_RUNNING);
        remove_wait_queue(sk_sleep(sk), &wait);
 
        down_write(&cmtp_session_sem);
@@ -394,7 +393,7 @@ int cmtp_add_connection(struct cmtp_connadd_req *req, struct socket *sock)
                err = cmtp_attach_device(session);
                if (err < 0) {
                        atomic_inc(&session->terminate);
-                       wake_up_process(session->task);
+                       wake_up_interruptible(sk_sleep(session->sock->sk));
                        up_write(&cmtp_session_sem);
                        return err;
                }
@@ -432,7 +431,11 @@ int cmtp_del_connection(struct cmtp_conndel_req *req)
 
                /* Stop session thread */
                atomic_inc(&session->terminate);
-               wake_up_process(session->task);
+
+               /* Ensure session->terminate is updated */
+               smp_mb__after_atomic();
+
+               wake_up_interruptible(sk_sleep(session->sock->sk));
        } else
                err = -ENOENT;