Date: Mon, 7 Jul 2014 20:50:05 +0200
From: Olivier Sobrie <olivier@sobrie.be>
To: Dan Williams <dcbw@redhat.com>
Cc: Jan Dumon <j.dumon@option.com>, linux-usb@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] hso: fix deadlock when receiving bursts of data
Message-ID: <20140707185005.GA1105@thinkoso.home>
Reply-To: Olivier Sobrie <olivier@sobrie.be>
References: <1404723967-24245-1-git-send-email-olivier@sobrie.be>
 <1404723967-24245-2-git-send-email-olivier@sobrie.be>
 <1404751280.22000.11.camel@dcbw.local>
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Hi Dan,

On Mon, Jul 07, 2014 at 11:41:20AM -0500, Dan Williams wrote:
> On Mon, 2014-07-07 at 11:06 +0200, Olivier Sobrie wrote:
> > When the module sends bursts of data, sometimes a deadlock happens in
> > the hso driver when the tty buffer doesn't get the chance to be flushed
> > quickly enough.
> > 
> > To avoid this, first, we remove the endless while loop in
> > put_rx_bufdata() which is the root cause of the deadlock.
> > Secondly, when there is no room anymore in the tty buffer, we set up a
> > timer of 100 msecs to give a chance to the upper layer to flush the tty
> > buffer and make room for new data.
> 
> I assume this problem happens when using PPP for data transfer, instead
> of using the network port that the modules expose?  Or maybe the NMEA
> port?  I can't imagine that AT commands would make this happen...

Yes it happens when using ppp for data transfer.
The transfer of a large file sometimes triggers the problem.

-- 
Olivier
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