linux-kernel - Re: [PATCH 4.4 054/108] mtd: cfi: convert inline functions to macros

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Date:   Wed, 7 Mar 2018 08:14:58 +0100
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Ben Hutchings <ben.hutchings@...ethink.co.uk>
Cc:     Arnd Bergmann <arnd@...db.de>, Richard Weinberger <richard@....at>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        stable@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4.4 054/108] mtd: cfi: convert inline functions to
 macros

On Mon, 05 Mar 2018 02:22:52 +0000
Ben Hutchings <ben.hutchings@...ethink.co.uk> wrote:

> On Thu, 2018-02-15 at 16:16 +0100, Greg Kroah-Hartman wrote:
> > 4.4-stable review patch.  If anyone has any objections, please let me know.
> > 
> > ------------------
> > 
> > From: Arnd Bergmann <arnd@...db.de>
> > 
> > commit 9e343e87d2c4c707ef8fae2844864d4dde3a2d13 upstream.  
> [...]
> > -static inline int map_word_andequal(struct map_info *map, map_word val1, map_word val2, map_word val3)
> > -{
> > -	int i;
> > -
> > -	for (i = 0; i < map_words(map); i++) {
> > -		if ((val1.x[i] & val2.x[i]) != val3.x[i])
> > -			return 0;
> > -	}
> > -
> > -	return 1;
> > -}  
> [...]
> > +#define map_word_andequal(map, val1, val2, val3)			\
> > +({									\
> > +	int i, ret = 1;							\
> > +	for (i = 0; i < map_words(map); i++) {				\
> > +		if (((val1).x[i] & (val2).x[i]) != (val2).x[i]) {	\  
> [...]
> 
> The right-hand side of this comparison is now using val2 instead of
> val3.  (This bug seems to be unfixed upstream.)

Indeed. This being said, it's not buggy since all users of
map_word_andequal() pass the same value to val2 and val3.

Maybe we should just patch the macro and all call-sites to remove val3.

> 
> Ben.
> 



-- 
Boris Brezillon, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com