From: David Miller <davem@davemloft.net>
To: gregkh@linuxfoundation.org
Cc: peter@hurleysoftware.com, linux-kernel@vger.kernel.org,
linux-serial@vger.kernel.org, sethb@digi.com,
aaro.koskinen@iki.fi, sam@ravnborg.org,
tsbogend@alpha.franken.de
Subject: Re: [PATCH 0/2] fixes for empty tx buffer breakage
Date: Thu, 10 Jul 2014 16:12:05 -0700 (PDT) [thread overview]
Message-ID: <20140710.161205.2079073830695357277.davem@davemloft.net> (raw)
In-Reply-To: <20140710231432.GA9423@kroah.com>
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Thu, 10 Jul 2014 16:14:32 -0700
> On Sun, Jul 06, 2014 at 11:29:51AM -0400, Peter Hurley wrote:
>> Cc: Seth Bollinger <sethb@digi.com>
>> Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
>> Cc: Sam Ravnborg <sam@ravnborg.org>
>> Cc: "David S. Miller" <davem@davemloft.net>
>> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
>>
>> Greg,
>>
>> I completed the audit of serial drivers after reports that
>> several Sun serial drivers were broken by
>> commit 717f3bbab3c7628736ef738fdbf3d9a28578c26c,
>> 'serial_core: Fix conditional start_tx on ring buffer not empty'.
>>
>> I apologize for not submitting this sooner. The delay was due to
>> an ongoing analysis of serial flow control prompted by Sam Ravnborg's
>> question:
>>
>> On 06/10/2014 03:24 PM, Sam Ravnborg wrote:
>> > I also noticed the typical pattern is:
>> >
>> > if (uart_circ_empty(xmit) || uart_tx_stopped(port))
>> >
>> > Should you use this pattern also in sunsab.c?
>>
>> Unfortunately, that analysis revealed that tx flow control is
>> largely SMP-unsafe, and it's fairly easy to corrupt the hardware
>> state wrt. the tty flow control state.
>>
>> I'm still working on the solutions to that; they're too
>> extensive to submit for 3.16 anyway.
>
> So these should go into 3.16-final? Or 3.17?
Definitely 3.16, this regression is several releases old.
next prev parent reply other threads:[~2014-07-10 23:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20140609205917.GA913@drone.musicnaut.iki.fi>
2014-07-06 15:29 ` [PATCH 0/2] fixes for empty tx buffer breakage Peter Hurley
2014-07-06 15:29 ` [PATCH 1/2] serial: Test for no tx data on tx restart Peter Hurley
2014-07-06 15:29 ` [PATCH 2/2] serial: arc_uart: Use uart_circ_empty() for open-coded comparison Peter Hurley
2014-07-10 23:14 ` [PATCH 0/2] fixes for empty tx buffer breakage Greg Kroah-Hartman
2014-07-10 23:12 ` David Miller [this message]
2014-07-10 23:29 ` Greg KH
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