From: Arnd Bergmann <arnd@arndb.de>
To: NamJae Jeon <linkinjeon@gmail.com>
Cc: linux-arch@vger.kernel.org
Subject: Re: 'hweight_long' include/linux/bitops.h compile warning problem.
Date: Mon, 20 Jun 2011 15:00:58 +0200 [thread overview]
Message-ID: <201106201500.58617.arnd@arndb.de> (raw)
In-Reply-To: <BANLkTi=ETn+LXtd20qkfcgrUngjqwVrVPg@mail.gmail.com>
On Monday 20 June 2011, NamJae Jeon wrote:
> I found compile warning while compiling module when using -Wsign-compare option.
>
> include/linux/bitops.h: In function 'hweight_long':
> include/linux/bitops.h:49: warning: signed and unsigned type in
> conditional expression
>
> I found the reason of this problem that the default return value of
> the below macro is signed.
>
> #define __const_hweight8(w) \
> ( (!!((w) & (1ULL << 0))) + \
> (!!((w) & (1ULL << 1))) + \
> (!!((w) & (1ULL << 2))) + \
> (!!((w) & (1ULL << 3))) + \
> (!!((w) & (1ULL << 4))) + \
> (!!((w) & (1ULL << 5))) + \
> (!!((w) & (1ULL << 6))) + \
> (!!((w) & (1ULL << 7))) )
>
> So, I try to add (unsigned long) in __const_hweight8 like this.
>
> #define __const_hweight8(w) (unsigned long ) \
> ( (!!((w) & (1ULL << 0))) + \
> (!!((w) & (1ULL << 1))) + \
> (!!((w) & (1ULL << 2))) + \
> (!!((w) & (1ULL << 3))) + \
> (!!((w) & (1ULL << 4))) + \
> (!!((w) & (1ULL << 5))) + \
> (!!((w) & (1ULL << 6))) + \
> (!!((w) & (1ULL << 7))) )
>
> so, I can't see compile warning after fixing it, Would you plz check this ?
Yes, this looks correct to me. Could you send the change as a proper patch
with your Signed-off-by:?
Arnd
next prev parent reply other threads:[~2011-06-20 13:01 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-20 7:59 'hweight_long' include/linux/bitops.h compile warning problem NamJae Jeon
2011-06-20 13:00 ` Arnd Bergmann [this message]
2011-06-21 6:11 ` NamJae Jeon
2011-06-21 6:11 ` NamJae Jeon
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