Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754639AbYGWFCh (ORCPT ); Wed, 23 Jul 2008 01:02:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752581AbYGWFC0 (ORCPT ); Wed, 23 Jul 2008 01:02:26 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:42260 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752527AbYGWFCZ (ORCPT ); Wed, 23 Jul 2008 01:02:25 -0400 Date: Tue, 22 Jul 2008 22:00:56 -0700 From: Andrew Morton To: Willy Tarreau 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: <20080722220056.234af367.akpm@linux-foundation.org> In-Reply-To: <20080723045230.GD29189@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> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2938 Lines: 90 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) ) _ 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. -- 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/