linux-kernel - RE: [PATCH v2] net: dsa: Remove VLA usage

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Message-ID: <6e5b57f59ca6420489d65392a1e8dbc8@AcuMS.aculab.com>
Date:   Mon, 30 Jul 2018 08:59:01 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Pavel Machek' <pavel@....cz>, Kees Cook <keescook@...omium.org>
CC:     "David S. Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Salvatore Mesoraca <s.mesoraca16@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>
Subject: RE: [PATCH v2] net: dsa: Remove VLA usage

From: Pavel Machek
> Sent: 29 July 2018 12:40
...
> > > +	unsigned long		*bitmap;
> > > +	unsigned long		_bitmap;
> >
> > This looks rather confusing. _bitmap -> bitmap_data? bitmap_bits?
> 
> Actually, AFAICT that long is not used as a long, but as array of
> bits. So maybe char bitmap_data[8] would be more appropriate?

Unfortunately the 'bitmap' functions are defined to work in a 
specific way on unsigned long[].
This means, for example, that they can't use the x86 'bit' instructions.

	David

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