Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754676AbYGWFGw (ORCPT ); Wed, 23 Jul 2008 01:06:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752473AbYGWFGm (ORCPT ); Wed, 23 Jul 2008 01:06:42 -0400 Received: from 1wt.eu ([62.212.114.60]:1925 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752389AbYGWFGl (ORCPT ); Wed, 23 Jul 2008 01:06:41 -0400 Date: Wed, 23 Jul 2008 07:06:03 +0200 From: Willy Tarreau To: Andrew Morton Cc: Krzysztof Halasa , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Stephen Hemminger , "David S. Miller" , Russell King Subject: Re: [bisected] kernel panic 2.6.22 -> 2.6.26-rc9+ Message-ID: <20080723050603.GG29189@1wt.eu> References: <20080713013107.23f060f2.akpm@linux-foundation.org> <20080713112230.e86ba9ae.akpm@linux-foundation.org> <20080713145525.51a1ca3a.akpm@linux-foundation.org> <20080723045230.GD29189@1wt.eu> <20080722220056.234af367.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080722220056.234af367.akpm@linux-foundation.org> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3217 Lines: 96 On Tue, Jul 22, 2008 at 10:00:56PM -0700, Andrew Morton wrote: > On Wed, 23 Jul 2008 06:52:31 +0200 Willy Tarreau wrote: > > > On Sun, Jul 13, 2008 at 02:55:25PM -0700, Andrew Morton wrote: > > > On Sun, 13 Jul 2008 23:51:06 +0200 Krzysztof Halasa wrote: > > > > > > > Andrew Morton writes: > > > > > > > > > --- a/include/asm-arm/bitops.h~a > > > > > +++ a/include/asm-arm/bitops.h > > > > > @@ -277,9 +277,16 @@ static inline int constant_fls(int x) > > > > > * the clz instruction for much better code efficiency. > > > > > */ > > > > > > > > > > -#define fls(x) \ > > > > > +#define __fls(x) \ > > > > > ( __builtin_constant_p(x) ? constant_fls(x) : \ > > > > > ({ int __r; asm("clz\t%0, %1" : "=r"(__r) : "r"(x) : "cc"); 32-__r; }) ) > > > > > + > > > > > +/* Implement fls() in C so that 64-bit args are suitably truncated */ > > > > > +static inline int fls(int x) > > > > > +{ > > > > > + return __fls(x); > > > > > +} > > > > > + > > > > > > > > Well, I like it more as it fixes all possible places instead of only > > > > fls64(). > > > > > > > > But... can't we just move the #define body into the inline fls(x)? > > > > Will there be other users of __fls(x)? It seems the > > > > __builtin_constant_p(x) works for inline functions. > > > > > > Could. That was a minimal&safe thing. > > > > > > > The above patch fixes the kernel panic, too. > > > > > > OK, thanks. > > > > Andrew, > > > > have you sent your patch to Linus ? I haven't seen it merged yet, and > > I'd like to get it into -stable too. > > This one? > > From: Andrew Morton > > arm's fls() is implemented as a macro, causing it to misbehave when passed > 64-bit arguments. Fix. > > Cc: Nickolay Vinogradov > Tested-by: Krzysztof Halasa > Signed-off-by: Andrew Morton > --- > > include/asm-arm/bitops.h | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff -puN include/asm-arm/bitops.h~arm-fix-fls-for-64-bit-arguments include/asm-arm/bitops.h > --- a/include/asm-arm/bitops.h~arm-fix-fls-for-64-bit-arguments > +++ a/include/asm-arm/bitops.h > @@ -277,9 +277,16 @@ static inline int constant_fls(int x) > * the clz instruction for much better code efficiency. > */ > > -#define fls(x) \ > +#define __fls(x) \ > ( __builtin_constant_p(x) ? constant_fls(x) : \ > ({ int __r; asm("clz\t%0, %1" : "=r"(__r) : "r"(x) : "cc"); 32-__r; }) ) > + > +/* Implement fls() in C so that 64-bit args are suitably truncated */ > +static inline int fls(int x) > +{ > + return __fls(x); > +} > + > #define ffs(x) ({ unsigned long __t = (x); fls(__t & -__t); }) > #define __ffs(x) (ffs(x) - 1) > #define ffz(x) __ffs( ~(x) ) > _ > yes, precisely this one. > Nope, I'm just kind of sitting on it. I'll put a stable@kernel.org tag > on it and send it to Russell I guess. Perfect, thanks! Willy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/