linux-kernel - Re: [PATCH v2 7/9] [media] v4l2: introduce v4l2

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 for Android: free password hash cracker in your pocket

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

Message-ID: <9019880.VVdOR6WRt1@wuerfel>
Date:	Fri, 18 Sep 2015 11:43:24 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Hans Verkuil <hverkuil@...all.nl>
Cc:	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	y2038@...ts.linaro.org,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	linux-api@...r.kernel.org, linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH v2 7/9] [media] v4l2: introduce v4l2_timeval

On Friday 18 September 2015 11:27:40 Hans Verkuil wrote:
> Ah, OK. Got it.
> 
> I think this is dependent on the upcoming media workshop next month. If we
> decide to redesign v4l2_buffer anyway, then we can avoid timeval completely.
> And the only place where we would need to convert it in the compat code
> hidden in the v4l2 core (likely v4l2-ioctl.c).

Ah, I think I understood the idea now, I missed that earlier when you mention
the idea.

So what you are saying here is that you could come up with a new unambiguous
(using only __u32 and __u64 types and no pointers) format that gets exposed
to a new set of ioctls, and then change the handling of the existing three
formats (native 64-bit, traditional 32-bit, and 32-bit with 64-bit time_t)
so they get converted into the new format by the common ioctl handling code?

> I am not really keen on having v4l2_timeval in all these drivers. I would
> have to check them anyway since I suspect that in several drivers the local
> timeval variable can be avoided by rewriting that part of the driver.

I've tried to do that for all the drivers where I could find an easy solution
in patch 6/9, but I'm sure you can do it for a couple more.

We could also do a lightweight redesign and use 'timespec64' internally
in all the drivers and then convert that to 'timeval' or the 64-bit
format of that in the ioctl handler. This is also something I tried at
some point but then found it a bit more intuitive to leave the normal ioctl
path alone and have an explicit type.

> Personally I am in favor of a redesigned v4l2_buffer: it's awkward to use
> with multiplanar formats, there is cruft in there that can be removed (timecode),
> and there is little space for additions (HW-specific timecodes, more buffer
> meta data, etc).
> 
> We'll see.

Ok.

	Arnd
--
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/