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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,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 34072C433E1 for ; Mon, 24 Aug 2020 19:22:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 019032074D for ; Mon, 24 Aug 2020 19:22:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="hB78woS9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727849AbgHXTWZ (ORCPT ); Mon, 24 Aug 2020 15:22:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727093AbgHXTWX (ORCPT ); Mon, 24 Aug 2020 15:22:23 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1A9BAC061573 for ; Mon, 24 Aug 2020 12:22:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=kYjuOG42Pf1wUxE3HuOUosmUkIHVzXaCDeTnguR2S+w=; b=hB78woS93z82XwwFsV7G/ATAG8 C0SM1mmWjKAl/yzV/7UkikVcMgxdHFKOo8uWwYoxDOIfynZUuCOokRpnyKKvJa4O/hujdcFNx/3zt Plkq6oRbJJclVBQ2UyfXi9SMfWhr4hNk7sCQITVQJwJ4Vq4tlXnA9/aIwhySYtzTksla+ts0CJOcl ZdUghgSdZpdoEycIpMHVX2zx1CISvNY5h6JHi72L3T3pmgGjgufMNiio6WB7bQUTO0IjyboPmc0VR zaCm1ojsYb4PYufBWQ/n1h2WQtwtImtjmPmg8YZ/WZCZP9boCKoGhm6SOGpbvsDn0DK/mexegKk4d LVI4TQfw==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kAI2o-0004PU-M2; Mon, 24 Aug 2020 19:22:14 +0000 Date: Mon, 24 Aug 2020 20:22:14 +0100 From: Matthew Wilcox To: Andrew Morton Cc: Miaohe Lin , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/mempool: Add 'else' to split mutually exclusive case Message-ID: <20200824192214.GF17456@casper.infradead.org> References: <20200824115354.7879-1-linmiaohe@huawei.com> <20200824121840.4cd7eb3dce03e8e1473221b3@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200824121840.4cd7eb3dce03e8e1473221b3@linux-foundation.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 24, 2020 at 12:18:40PM -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. Not with the comments where they are