Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752181AbaBXMQJ (ORCPT ); Mon, 24 Feb 2014 07:16:09 -0500 Received: from nat28.tlf.novell.com ([130.57.49.28]:56552 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751450AbaBXMQI convert rfc822-to-8bit (ORCPT ); Mon, 24 Feb 2014 07:16:08 -0500 Message-Id: <530B4613020000780011EB8E@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.2 Date: Mon, 24 Feb 2014 12:16:03 +0000 From: "Jan Beulich" To: "Daniel Borkmann" Cc: , , , , , , Subject: Re: [PATCH 2/3] x86/hash: swap parameters of crc32_u32() References: <53073986020000780011E2E1@nat28.tlf.novell.com> <5308938A.8070506@redhat.com> <530B0AF2020000780011E97B@nat28.tlf.novell.com> <530B1D60.8010602@redhat.com> <530B32A4020000780011EACB@nat28.tlf.novell.com> <530B3102.4050102@redhat.com> In-Reply-To: <530B3102.4050102@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> On 24.02.14 at 12:46, Daniel Borkmann wrote: > On 02/24/2014 11:53 AM, Jan Beulich wrote: >>>>> On 24.02.14 at 11:22, Daniel Borkmann wrote: >>> On 02/24/2014 09:03 AM, Jan Beulich wrote: >>>>>>> On 22.02.14 at 13:09, Daniel Borkmann wrote: >>>>> On 02/21/2014 11:33 AM, Jan Beulich wrote: >>>>>> ... to match its two callers (i.e. the alternative would have been to >>>>>> swap the arguments at the call sites). >>>>>> >>>>>> Signed-off-by: Jan Beulich >>>>>> Cc: Francesco Fusco >>>>>> Cc: Daniel Borkmann >>>>>> Cc: Thomas Graf >>>>>> Cc: David S. Miller >>>>>> --- >>>>>> arch/x86/lib/hash.c | 2 +- >>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>>> >>>>>> --- 3.14-rc3-x86-hash-crc32.orig/arch/x86/lib/hash.c >>>>>> +++ 3.14-rc3-x86-hash-crc32/arch/x86/lib/hash.c >>>>>> @@ -37,7 +37,7 @@ >>>>>> #include >>>>>> #include >>>>>> >>>>>> -static inline u32 crc32_u32(u32 crc, u32 val) >>>>>> +static inline u32 crc32_u32(u32 val, u32 crc) >>>>>> { >>>>>> #ifdef CONFIG_AS_CRC32 >>>>>> asm ("crc32l %1,%0\n" : "+r" (crc) : "rm" (val)); >>>>> >>>>> Can you elaborate? >>>>> >>>>> Sorry, I need to ask here (even if it's a stupid question ;)) if this >>>>> change is safe to do; are referring to a cleanup or fixing a concrete >>>>> bug? The code is a modified version of the DPDK hash which you can find >>>>> in [1]. Arguments of the caller are in the correct order, afaik. >>>>> >>>>> [1] http://dpdk.org/browse/dpdk/tree/lib/librte_hash/rte_hash_crc.h >>>> >>>> Yes, that file appears to be correct: >>>> >>>> rte_hash_crc_4byte(uint32_t data, uint32_t init_val) >>>> >>>> as opposed to >>>> >>>> static inline u32 crc32_u32(u32 crc, u32 val) >>>> >>>> (quite obviously data <-> val and crc <-> init_val, supported >>>> by the second argument in each caller being named "seed"). >>> >>> If you want a more descriptive name, feel free to rename these vars, >>> but check it yourself, it's not a bug as you claim; results are the >>> same: >> >> Even if the results are the same (operands being symmetric?), check >> the generated code for your version and the fixed up one: The crc32 >> instruction allows one of its operands to be in memory for a reason. > > I'm fine with that. But then, please reflect these details in your > commit message. Hmm, to me it says exactly that. Jan -- 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/