linux-kernel - Re: [RFC: PATCH 2/2] iio: adc: exynos_adc: Handle timeout and race conditions

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: <CAD=FV=XHKn_vqv7-rqpraJy_V2kyBfo98WdMsAJ5eXhADc_rmA@mail.gmail.com>
Date:	Fri, 5 Apr 2013 07:56:14 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Lars-Peter Clausen <lars@...afoo.de>
Cc:	Naveen Krishna Chatradhi <ch.naveen@...sung.com>,
	linux-iio <linux-iio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-samsung-soc@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Naveen Krishna <naveenkrishna.ch@...il.com>
Subject: Re: [RFC: PATCH 2/2] iio: adc: exynos_adc: Handle timeout and race conditions

Lars,

On Fri, Apr 5, 2013 at 1:53 AM, Lars-Peter Clausen <lars@...afoo.de> wrote:
> Since we sleep inside the protected section we need to use a mutex.

Ah, good point.

> It's not the timeout case I'm worried about, but the case where the transfer
> is interrupted by the user. Even though it is rather unlikely for the
> problem to occur we should still try to avoid it, this is one of these
> annoying heisenbugs that happen once in a while and nobody is able to
> reproduce them.

Yes, of course.  Then we can also get extra confidence that the reset
logic works well by stressing out this case...  :)

This makes me think, though.  Given how fast we expect the ADC
transaction to finish, would there be any benefit to making the wait
non-interruptible and then shortening the timeout a whole lot.  If we
shortened to 1ms then we're really not "non-interruptible" for very
long and there's less chance of subtle bugs in the way that reset
works.

-Doug
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/