Patch "Bluetooth: bnep: fix possible might sleep error in bnep_session" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    Bluetooth: bnep: fix possible might sleep error in bnep_session

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     bluetooth-bnep-fix-possible-might-sleep-error-in-bnep_session.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 25717382c1dd0ddced2059053e3ca5088665f7a5 Mon Sep 17 00:00:00 2001
From: Jeffy Chen <jeffy.chen@rock-chips.com>
Date: Tue, 27 Jun 2017 17:34:42 +0800
Subject: Bluetooth: bnep: fix possible might sleep error in bnep_session

From: Jeffy Chen <jeffy.chen@rock-chips.com>

commit 25717382c1dd0ddced2059053e3ca5088665f7a5 upstream.

It looks like bnep_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>

---
 net/bluetooth/bnep/core.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

--- a/net/bluetooth/bnep/core.c
+++ b/net/bluetooth/bnep/core.c
@@ -484,16 +484,16 @@ static int bnep_session(void *arg)
 	struct net_device *dev = s->dev;
 	struct sock *sk = s->sock->sk;
 	struct sk_buff *skb;
-	wait_queue_t wait;
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
 
 	BT_DBG("");
 
 	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(&s->terminate))
 			break;
@@ -515,9 +515,8 @@ static int bnep_session(void *arg)
 				break;
 		netif_wake_queue(dev);
 
-		schedule();
+		wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
 	}
-	__set_current_state(TASK_RUNNING);
 	remove_wait_queue(sk_sleep(sk), &wait);
 
 	/* Cleanup session */
@@ -666,7 +665,7 @@ int bnep_del_connection(struct bnep_conn
 	s = __bnep_get_session(req->dst);
 	if (s) {
 		atomic_inc(&s->terminate);
-		wake_up_process(s->task);
+		wake_up_interruptible(sk_sleep(s->sock->sk));
 	} else
 		err = -ENOENT;
 


Patches currently in stable-queue which might be from jeffy.chen@rock-chips.com are

queue-4.9/bluetooth-cmtp-fix-possible-might-sleep-error-in-cmtp_session.patch
queue-4.9/bluetooth-hidp-fix-possible-might-sleep-error-in-hidp_session_thread.patch
queue-4.9/bluetooth-bnep-fix-possible-might-sleep-error-in-bnep_session.patch