linux-kernel - Re: [RFC PATCH 0/3] fix *pbl format support

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Date:	Wed, 16 Sep 2015 14:53:56 +0200
From:	Maurizio Lombardi <mlombard@...hat.com>
To:	Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:	tj@...nel.org, joe@...ches.com, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 0/3] fix *pbl format support

Hi,

On 09/16/2015 02:27 PM, Rasmus Villemoes wrote:
> 
> If we want to fix the problem with 3/3, then this seems obviously
> necessary. There may be stuff we want to optimize later (for example, I
> don't think we should always make a local copy of the entire struct;

Yes I know, I just tried not to break anything in the process,
optimizations can be done later.

> I haven't looked carefully at your code, but it does seem that you make
> sure that at least the return value is as expected, which will make
> kasprintf work. But it seems there is another kasprintf
> problem. [reminder: kasprintf works by doing a va_copy, then doing a
> first call of vsnprintf, passing NULL for the buffer and 0 for the
> length to determine the size to allocate, and then doing the actual
> formatting with a second call]

Ah, you're right, PATCH 2 is broken because I didn't think to the case
you described.
Please ignore it, thanks for catching this.

> I'm not yet completely convinced this is the right solution. Obviously,
> if other problems with the small .field_width size show up, this might
> be necessary, but as long as it's only the %pb formatter (and so far
> only a single user of that), I think smaller/other hammers should be
> thought about. So far I think there've been two alternatives: (1)
> reintroduce the dedicated bitmap pretty printer(s)

I have no problem with that, at least it will work again.

Thanks for the review,
Maurizio Lombardi
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