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]
Message-ID: <20151105152943.GP18409@sirena.org.uk>
Date:	Thu, 5 Nov 2015 15:29:43 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Vignesh R <vigneshr@...com>
Cc:	Tony Lindgren <tony@...mide.com>,
	Michal Suchanek <hramrach@...il.com>,
	Russell King <linux@....linux.org.uk>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-mtd@...ts.infradead.org, linux-spi@...r.kernel.org
Subject: Re: [PATCH v2 1/5] spi: introduce mmap read support for spi flash
 devices

On Thu, Nov 05, 2015 at 05:59:36PM +0530, Vignesh R wrote:
> On 11/04/2015 08:09 PM, Mark Brown wrote:

> > It's a bit worrying that this doesn't sync with the message queue except
> > via the mutex: this means that we might be out of order with respect to
> > any asynchronous transfers that are happening on the device.  I'm not
> > sure that this is a practical problem, though there is some risk of
> > unfair scheduling that would have to be under extreme load and it might
> > make sense to prioritise reads anyway.

> Since mmap interface is used only by mtd flash drivers and since almost
> all mtd flash devices use synchronous transfers (spi_sync()), IMO, there
> wont be out of order problem wrt mtd flashes.
> But mmap read might delay transfers queued for non mtd flash devices. It
> is difficult to wait for all transfers already queued to be pumped out
> by __spi_pump_messages() and then do the mmap transfer. Do you have any
> thoughts on how to sync with message queue?

Like I say I think it probably doesn't matter.  The main issue would be
with other devices sharing the bus with a flash chip.

Download attachment "signature.asc" of type "application/pgp-signature" (474 bytes)

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ