linux-kernel - Re: [PATCH v4 2/4] drm/rockchip: add an common abstracted PSR driver

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:	Sun, 24 Jul 2016 15:08:50 +0800
From:	Yakir Yang <ykk@...k-chips.com>
To:	Doug Anderson <dianders@...omium.org>
Cc:	Mark Yao <yzq@...k-chips.com>, Inki Dae <inki.dae@...sung.com>,
	Jingoo Han <jingoohan1@...il.com>,
	Heiko Stuebner <heiko@...ech.de>,
	Javier Martinez Canillas <javier@....samsung.com>,
	Stéphane Marchesin <marcheu@...omium.org>,
	Sean Paul <seanpaul@...omium.org>,
	Tomasz Figa <tfiga@...omium.org>,
	David Airlie <airlied@...ux.ie>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Thierry Reding <treding@...dia.com>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Emil Velikov <emil.l.velikov@...il.com>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>
Subject: Re: [PATCH v4 2/4] drm/rockchip: add an common abstracted PSR driver

Doug,

On 07/23/2016 12:04 PM, Doug Anderson wrote:
> Yakir,
>
> On Wed, Jul 13, 2016 at 9:15 PM, Yakir Yang <ykk@...k-chips.com> wrote:
>> +static void psr_set_state(struct psr_drv *psr, enum psr_state state)
>> +{
>> +       mutex_lock(&psr->state_mutex);
>> +
>> +       if (psr->state == state) {
>> +               mutex_unlock(&psr->state_mutex);
>> +               return;
>> +       }
>> +
>> +       psr->state = state;
>> +       switch (state) {
>> +       case PSR_ENABLE:
>> +               psr->set(psr->encoder, true);
>> +               break;
>> +
>> +       case PSR_DISABLE:
>> +       case PSR_FLUSH:
>> +               psr->set(psr->encoder, false);
>> +               break;
>> +       };
>> +
>> +       mutex_unlock(&psr->state_mutex);
>> +}
>> +
>> +static void psr_flush_handler(unsigned long data)
>> +{
>> +       struct psr_drv *psr = (struct psr_drv *)data;
>> +
>> +       if (!psr || psr->state != PSR_FLUSH)
>> +               return;
>> +
>> +       psr_set_state(psr, PSR_ENABLE);
> As mentioned in a separate thread, this is probably not OK.
> psr_set_state() grabs a mutex and that might sleep.  ...but
> psr_flush_handler() is a timer.  I'm nearly certain that timers can't
> sleep.
>
> I believe this is the source of "sleeping function called from invalid
> context" that I've seen at times.

Thanks for your reported, i have wrote a patch[0] to fix this problem in 
my v5. If you're happy to review, that would be great ;)

[0]: https://patchwork.kernel.org/patch/9244805/

- Yakir

>
> -Doug
>
>
>