linux-kernel - Re: [PATCH v1 06/12] serial: 8250_dma: stop ongoing RX DMA on exception

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 8 Apr 2016 11:07:39 +0300
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	Peter Hurley <peter@...leysoftware.com>
Cc:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Vinod Koul <vinod.koul@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	dmaengine <dmaengine@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Puustinen, Ismo" <ismo.puustinen@...el.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>
Subject: Re: [PATCH v1 06/12] serial: 8250_dma: stop ongoing RX DMA on exception

On Fri, Apr 8, 2016 at 2:54 AM, Peter Hurley <peter@...leysoftware.com> wrote:
> On 04/07/2016 01:37 PM, Andy Shevchenko wrote:
>> If we get an exeption interrupt. i.e. UART_IIR_RLSI, stop any ongoing RX DMA
>> transfer otherwise it might generates more spurious interrupts and make port
>> unavailable anymore.
>
> Then how to know which rx byte the error is for if dma continues anyway?
> What if there are multiple error bytes?

And how should it work?
We get an interrupt during DMA, if we don't stop DMA it will be racy
with direct readings.

>
>
>> As has been seen on Intel Broxton system:
>
> This system shouldn't be setup for UART DMA imo.

Same approach is done in 8250_omap.

-- 
With Best Regards,
Andy Shevchenko