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From:   Archie Pusaka <apusaka@google.com>
Date:   Wed, 18 Mar 2020 20:41:38 +0800
Message-ID: <CAJQfnxELMMDa6nbxRUrW46VjEBj6Txfeym62PKi+R3iXHKU0CQ@mail.gmail.com>
Subject: Re: [Bluez PATCH v1] input: disconnect intr channel before ctrl channel
To:     Marcel Holtmann <marcel@holtmann.org>
Cc:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
        linux-bluetooth <linux-bluetooth@vger.kernel.org>
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> > I see, we shutdown the socket immediately since the socket API itself
> > don't seem to have a concept of disconnect syscall not sure if other
> > values could be passed to shutdown second parameter to indicate we
> > want to actually wait it to be disconnected.

I don't think the second parameter matters, I tried every possible
valid values and intr_watch_cb is still called without waiting for the
response.

>
> in a blocking synchronous system call world we have SO_LINGER for that. In the world of asynchronous IO handling (what we do), we need to check what is the right way of handling this.
>

I spot this piece of code [1] which utilizes getsockopt to query
socket connection information from the kernel space to the user space.
We can use a similar method to query whether (sk->sk_state ==
BT_CLOSED), which is only true when we get the response.
What do you think?

[1] https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/tree/net/bluetooth/l2cap_sock.c#n476