Re: [4.1.0-07254-gc13c810] Regression: Bluetooth not working.

Hi J=C3=B6rg

On Tue, 30 Jun 2015 16:58:13 +0200
J=C3=B6rg Otte [off-list ref] wrote:

quoted

Regarding the system hang issue, it looks like the problem is caused by=

 the list_del().

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According to the list.h, this macro puts the entry into invalid state a=

nd it causes the device hang in the l2cap_core.c

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    /**
     * list_del - deletes entry from list.
     * @entry: the element to delete from the list.
     * Note: list_empty() on entry does not return true after this, the=

 entry is

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     * in an undefined state.
     */

So, one way to fix this issue is using the list_del_init() instead.

Can you try this patch to see if it resolve the issue? No need to rever=

t any patch.

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I ran a quick test with a different scenarios and it looks good to me s=

o far.

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diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 51594fb..45fffa4 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c

@@ -1634,7 +1634,7 @@ void l2cap_unregister_user(struct l2cap_conn *con=

n, struct l2cap_user *user)

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        if (list_empty(&user->list))
                goto out_unlock;

-       list_del(&user->list);
+       list_del_init(&user->list);
        user->remove(conn, user);

 out_unlock:

@@ -1648,7 +1648,7 @@ static void l2cap_unregister_all_users(struct l2c=

ap_conn *conn)

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        while (!list_empty(&conn->users)) {
                user =3D list_first_entry(&conn->users, struct l2cap_us=

er, list);

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-               list_del(&user->list);
+               list_del_init(&user->list);
                user->remove(conn, user);
        }
 }

Regards,
Tedd Ho-Jeong An

=20
I now have both patche applied and no revert. Looks good so far.
=20
Thanks, J=C3=B6rg

Thanks for testing the patch. I submitted the patch just in case.
Now, I am tossing the ball to Marcel. :)

Regards,
Tedd