From: Andrei Emeltchenko <Andrei.Emeltchenko.news@gmail.com>
To: Marcel Holtmann <marcel@holtmann.org>
Cc: Mat Martineau <mathewm@codeaurora.org>,
linux-bluetooth@vger.kernel.org, gustavo@padovan.org
Subject: Re: [PATCH 1/6] Bluetooth: Fix deadlock when closing socket
Date: Fri, 7 Sep 2012 17:08:14 +0300 [thread overview]
Message-ID: <20120907140813.GC22944@aemeltch-MOBL1> (raw)
In-Reply-To: <1346962251.21200.119.camel@aeonflux>
Hi Marcel,
On Thu, Sep 06, 2012 at 01:10:51PM -0700, Marcel Holtmann wrote:
> Hi Mat,
>
> > > If we have unacked frames when closing bluetooth socket we deadlock
> > > since conn->chan_lock, chan->lock and socket lock are taken. Remove
> > > __l2cap_wait_ack completely.
> > >
> > > Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
> >
> > I don't think you want to remove this code completely, at least not
> > without giving some thought to the problem it is solving.
> >
> > The problem is that programs may have an open socket which they send
> > some data on, then immediately close. There is no feedback when data
> > is actually sent over the air, so the socket may end up getting torn
> > down while there is still data in the HCI tx buffer or some data was
> > lost and needs to be retransmitted. Waiting for an acknowledgement
> > confirms that the application's sent data made it to the remote
> > device.
> >
> > Without this code, it's difficult to use l2test on a number of
> > qualification tests. Profiles or applications using ERTM may depend
> > on the "wait for ack before closing" behavior in order to have a clean
> > disconnect.
>
> isn't that what we have SO_LINGER for?
Looking at the code I suspect that SO_LINGER is not working. Maybe we need
to merge linger code and wait_ack stuff.
Best regards
Andrei Emeltchenko
next prev parent reply other threads:[~2012-09-07 14:08 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-06 12:05 [PATCH 1/6] Bluetooth: Fix deadlock when closing socket Andrei Emeltchenko
2012-09-06 12:05 ` [PATCH 2/6] Bluetooth: Fix freeing uninitialized delayed works Andrei Emeltchenko
2012-09-06 17:03 ` Mat Martineau
2012-09-08 20:28 ` Gustavo Padovan
2012-09-06 12:05 ` [PATCH 3/6] Bluetooth: trivial: Make hci_chan_del return void Andrei Emeltchenko
2012-09-08 20:33 ` Gustavo Padovan
2012-09-06 12:05 ` [PATCH 4/6] Bluetooth: trivial: Remove empty line Andrei Emeltchenko
2012-09-08 20:34 ` Gustavo Padovan
2012-09-06 12:05 ` [PATCH 5/6] Bluetooth: debug: Print refcnt for hci_dev Andrei Emeltchenko
2012-09-08 21:13 ` Gustavo Padovan
2012-09-06 12:05 ` [PATCH 6/6] Bluetooth: AMP: Add Read Data Block Size to amp_init Andrei Emeltchenko
2012-09-08 21:14 ` Gustavo Padovan
2012-09-06 17:01 ` [PATCH 1/6] Bluetooth: Fix deadlock when closing socket Mat Martineau
2012-09-06 20:10 ` Marcel Holtmann
2012-09-07 14:08 ` Andrei Emeltchenko [this message]
2012-09-07 17:00 ` Mat Martineau
2012-09-08 21:05 ` Gustavo Padovan
2012-09-10 8:23 ` [RFCv0] Bluetooth: Fix SO_LINGER in L2CAP Andrei Emeltchenko
2012-09-10 10:43 ` Anderson Lizardo
2012-09-10 10:55 ` Andrei Emeltchenko
2012-09-07 14:07 ` [PATCH 1/6] Bluetooth: Fix deadlock when closing socket Andrei Emeltchenko
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