linux-kernel - Re: [PATCH] fbmem: fix copy_from/to

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Message-ID: <a2776ec50901190029s28e663c6m1dc277484e143ac2@mail.gmail.com>
Date:	Mon, 19 Jan 2009 09:29:46 +0100
From:	Andrea Righi <righi.andrea@...il.com>
To:	Harvey Harrison <harvey.harrison@...il.com>
Cc:	Stefan Richter <stefanr@...6.in-berlin.de>,
	Johannes Weiner <hannes@...xchg.org>,
	Dave Jones <davej@...hat.com>,
	Johannes Weiner <hannes@...urebad.de>,
	Krzysztof Helt <krzysztof.h1@...pl>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fbmem: fix copy_from/to_user() with mutex held

On Mon, Jan 19, 2009 at 9:10 AM, Harvey Harrison
<harvey.harrison@...il.com> wrote:
> On Mon, 2009-01-19 at 09:05 +0100, Stefan Richter wrote:
>> Stefan Richter wrote:
>> > Andrea Righi wrote:
>> >> +struct fb_info *get_fb_info(struct fb_info *info)
>> >> +__acquires(&info->lock)
>> >> +{
>> >> +  mutex_lock(&info->lock);
>> >> +  if (!info->fbops) {
>> >> +          mutex_unlock(&info->lock);
>> >> +          return NULL;
>> >> +  }
>> >> +  return info;
>> >> +}
>> >> +
>> >> +void put_fb_info(struct fb_info *info)
>> >> +__releases(&info->lock)
>> >> +{
>> >> +  mutex_unlock(&info->lock);
>> >> +}
>> >> +
>> >
>> > These are IMO bad function names.
>>
>> PS:  The return value of the mutex_lock wrapper is also bad.  A bool or
>> int would IMO be clearer, similar to the return value of mutex_trylock.
>
> That, and there is no possible way to get the sparse annotations right
> for that function, which means you'll get no help from sparse in lock
> checking.
>
> So I'd suggest just opencoding these where needed instead of the
> wrappers.
>
> Harvey
>

OK, thanks for all the suggestions. I'll fix everything and repost a
new patch ASAP.

-Andrea
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