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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 B4D02C2D0DB for ; Wed, 29 Jan 2020 18:18:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9A88E206D4 for ; Wed, 29 Jan 2020 18:18:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727266AbgA2SSK (ORCPT ); Wed, 29 Jan 2020 13:18:10 -0500 Received: from mx2.suse.de ([195.135.220.15]:43660 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726823AbgA2SSK (ORCPT ); Wed, 29 Jan 2020 13:18:10 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 925F4B28E; Wed, 29 Jan 2020 18:18:08 +0000 (UTC) From: Davidlohr Bueso To: colyli@suse.de, kent.overstreet@gmail.com Cc: linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org, dave@stgolabs.net, Davidlohr Bueso Subject: [PATCH] bcache: optimize barrier usage for Rmw atomic bitops Date: Wed, 29 Jan 2020 10:08:02 -0800 Message-Id: <20200129180802.24626-1-dave@stgolabs.net> X-Mailer: git-send-email 2.16.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We can avoid the unnecessary barrier on non LL/SC architectures, such as x86. Instead, use the smp_mb__after_atomic(). Signed-off-by: Davidlohr Bueso --- drivers/md/bcache/writeback.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index 4a40f9eadeaf..284ff10f480f 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -183,7 +183,7 @@ static void update_writeback_rate(struct work_struct *work) */ set_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags); /* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */ - smp_mb(); + smp_mb__after_atomic(); /* * CACHE_SET_IO_DISABLE might be set via sysfs interface, @@ -193,7 +193,7 @@ static void update_writeback_rate(struct work_struct *work) test_bit(CACHE_SET_IO_DISABLE, &c->flags)) { clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags); /* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */ - smp_mb(); + smp_mb__after_atomic(); return; } @@ -229,7 +229,7 @@ static void update_writeback_rate(struct work_struct *work) */ clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags); /* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */ - smp_mb(); + smp_mb__after_atomic(); } static unsigned int writeback_delay(struct cached_dev *dc, -- 2.16.4