linux-kernel - Re: [PATCH] pwm-backlight: add regulator and GPIO support

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:	Wed, 4 Jul 2012 13:27:33 +0100
From:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
To:	Alex Courbot <acourbot@...dia.com>
Cc:	Sascha Hauer <s.hauer@...gutronix.de>,
	Thierry Reding <thierry.reding@...onic-design.de>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>
Subject: Re: [PATCH] pwm-backlight: add regulator and GPIO support

On Wed, Jul 04, 2012 at 09:26:58PM +0900, Alex Courbot wrote:
> On 07/04/2012 07:48 PM, Sascha Hauer wrote:>> +

> > This looses several resources allocated earlier, like the enable gpio
> > and the pwm. This is really bad here since I have no regulator specified
> > and devm_regulator_get returns with -EPROBE_DEFER. Next time the core
> > tries to probe the driver the driver bails out because the gpio and the
> > pwm is already requested.

> That's very bad indeed. I assumed that the kernel would free
> devm-allocated resources after probe returned -EPROBE_DEFER, so that
> probe could reallocate them the next time it is called. Apparently
> that was wrong. Do you know what would the right approach be in this
> case? Does the kernel preserve the device structure and its
> associated data between the two calls to probe? If so, I could just
> check whether the private data has already been constructed to know
> which state we are in and continue from there.

I'd really expect the devm_ functions to behave as you expect - if they
don't currently we should probably fix them so that they do otherwise
we're going to be in for a lot of surprises and probe deferral becomes a
lot more cumbersome to use.
--
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/