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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 49D3FECDFB1 for ; Tue, 17 Jul 2018 18:27:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0BCC4206B8 for ; Tue, 17 Jul 2018 18:27:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0BCC4206B8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730123AbeGQTBV (ORCPT ); Tue, 17 Jul 2018 15:01:21 -0400 Received: from mga09.intel.com ([134.134.136.24]:62540 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729708AbeGQTBV (ORCPT ); Tue, 17 Jul 2018 15:01:21 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Jul 2018 11:27:29 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,366,1526367600"; d="scan'208";a="75549933" Received: from ray.jf.intel.com (HELO [10.7.201.150]) ([10.7.201.150]) by orsmga002.jf.intel.com with ESMTP; 17 Jul 2018 11:27:29 -0700 Subject: Re: [PATCH v2 1/7] swap: Add comments to lock_cluster_or_swap_info() To: "Huang, Ying" , Andrew Morton References: <20180717005556.29758-1-ying.huang@intel.com> <20180717005556.29758-2-ying.huang@intel.com> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Michal Hocko , Johannes Weiner , Shaohua Li , Hugh Dickins , Minchan Kim , Rik van Riel , Daniel Jordan , Dan Williams From: Dave Hansen Openpgp: preference=signencrypt Autocrypt: addr=dave.hansen@linux.intel.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180717005556.29758-2-ying.huang@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/16/2018 05:55 PM, Huang, Ying wrote: > +/* > + * For non-HDD swap devices, the fine grained cluster lock is used to > + * protect si->swap_map. But cluster and cluster locks isn't > + * available for HDD, so coarse grained si->lock will be used instead > + * for that. > + */ > static inline struct swap_cluster_info *lock_cluster_or_swap_info( > struct swap_info_struct *si, > unsigned long offset) This nomenclature is not consistent with the rest of the file. We call a "non-HDD" device an "ssd" absolutely everywhere else in the file. Why are you calling it a non-HDD here? (fwiw, HDD _barely_ hits my acronym cache anyway). How about this? /* * Determine the locking method in use for this device. Return * swap_cluster_info if SSD-style cluster-based locking is in place. */ static inline struct swap_cluster_info *lock_cluster_or_swap_info( struct swap_info_struct *si, unsigned long offset) { struct swap_cluster_info *ci; /* Try to use fine-grained SSD-style locking if available: */ ci = lock_cluster(si, offset); /* Otherwise, fall back to traditional, coarse locking: */ if (!ci) spin_lock(&si->lock); return ci; } Which reminds me? Why do we even bother having two locking models?