linux-kernel - Re: [PATCH 2/5] Fonts: Make font size unsigned in font

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Message-ID: <20201028081844.GS401619@phenom.ffwll.local>
Date:   Wed, 28 Oct 2020 09:18:44 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Peilin Ye <yepeilin.cs@...il.com>
Cc:     Daniel Vetter <daniel@...ll.ch>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "James E . J . Bottomley" <James.Bottomley@...senpartnership.com>,
        Helge Deller <deller@....de>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Jiri Slaby <jirislaby@...nel.org>,
        linux-parisc@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] Fonts: Make font size unsigned in font_desc

On Wed, Oct 28, 2020 at 01:43:07AM -0400, Peilin Ye wrote:
> On Tue, Oct 27, 2020 at 07:50:58PM +0100, Daniel Vetter wrote:
> > On Tue, Oct 27, 2020 at 12:33:05PM -0400, Peilin Ye wrote:
> > > It is improper to define `width` and `height` as signed in `struct
> > > font_desc`. Make them unsigned. Also, change the corresponding printk()
> > > format identifiers from `%d` to `%u`, in sti_select_fbfont().
> > > 
> > > Signed-off-by: Peilin Ye <yepeilin.cs@...il.com>
> > 
> > I'm not entirely sure of the motivation here ... height/width should never
> > ever be even close to the limit here. Or have you seen integer math that
> > could potentially go wrong if we go with unsigned instead of int?
> 
> Oh... No, I have not. I just thought we shouldn't represent a length
> using a signed value. Also, width and height in console_font are
> unsigned int - that shouldn't matter that much though.

Oh this is actually a good reason, since that's the uapi structure. And so
using the exact same signedness should help a bit with accidental casting
bugs.

If you mention this in the commit message I think this is good to go.
-Daniel

> 
> [3/5] doesn't hunk properly without this patch, I'll send a v2 for [3/5]
> soon.
> 
> Peilin
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch