From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23FBAC433E1 for ; Mon, 24 Aug 2020 19:27:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F0823208E4 for ; Mon, 24 Aug 2020 19:27:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726664AbgHXT1O (ORCPT ); Mon, 24 Aug 2020 15:27:14 -0400 Received: from smtprelay0041.hostedemail.com ([216.40.44.41]:54330 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725976AbgHXT1O (ORCPT ); Mon, 24 Aug 2020 15:27:14 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay03.hostedemail.com (Postfix) with ESMTP id 4539D837F24F; Mon, 24 Aug 2020 19:27:13 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: lunch29_4b01b2827055 X-Filterd-Recvd-Size: 2829 Received: from XPS-9350.home (unknown [47.151.133.149]) (Authenticated sender: joe@perches.com) by omf01.hostedemail.com (Postfix) with ESMTPA; Mon, 24 Aug 2020 19:27:12 +0000 (UTC) Message-ID: <37bbda0e0d94d3324210fa807f4061a9e9bd66bc.camel@perches.com> Subject: Re: [PATCH] mm/mempool: Add 'else' to split mutually exclusive case From: Joe Perches To: Andrew Morton , Miaohe Lin Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Mon, 24 Aug 2020 12:27:10 -0700 In-Reply-To: <20200824121840.4cd7eb3dce03e8e1473221b3@linux-foundation.org> References: <20200824115354.7879-1-linmiaohe@huawei.com> <20200824121840.4cd7eb3dce03e8e1473221b3@linux-foundation.org> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.36.4-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2020-08-24 at 12:18 -0700, Andrew Morton wrote: > On Mon, 24 Aug 2020 07:53:54 -0400 Miaohe Lin wrote: > > > Add else to split mutually exclusive case and avoid some unnecessary check. > > > > --- a/mm/mempool.c > > +++ b/mm/mempool.c > > @@ -60,9 +60,8 @@ static void check_element(mempool_t *pool, void *element) > > /* Mempools backed by slab allocator */ > > if (pool->free == mempool_free_slab || pool->free == mempool_kfree) > > __check_element(pool, element, ksize(element)); > > - > > /* Mempools backed by page allocator */ > > - if (pool->free == mempool_free_pages) { > > + else if (pool->free == mempool_free_pages) { > > int order = (int)(long)pool->pool_data; > > void *addr = kmap_atomic((struct page *)element); > > > > It doesn't seem to change code generation (compiler is smart), but I > think it helps readability. style: braces should be added to the first test. Perhaps better as: --- mm/mempool.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/mm/mempool.c b/mm/mempool.c index 79bff63ecf27..d0206eab86a4 100644 --- a/mm/mempool.c +++ b/mm/mempool.c @@ -57,12 +57,12 @@ static void __check_element(mempool_t *pool, void *element, size_t size) static void check_element(mempool_t *pool, void *element) { - /* Mempools backed by slab allocator */ - if (pool->free == mempool_free_slab || pool->free == mempool_kfree) + if (pool->free == mempool_free_slab || + pool->free == mempool_kfree) { + /* Mempools backed by slab allocator */ __check_element(pool, element, ksize(element)); - - /* Mempools backed by page allocator */ - if (pool->free == mempool_free_pages) { + } else if (pool->free == mempool_free_pages) { + /* Mempools backed by page allocator */ int order = (int)(long)pool->pool_data; void *addr = kmap_atomic((struct page *)element);