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 63837C2D0DB for ; Wed, 29 Jan 2020 18:23:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 47862206F0 for ; Wed, 29 Jan 2020 18:23:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727455AbgA2SXD (ORCPT ); Wed, 29 Jan 2020 13:23:03 -0500 Received: from mx2.suse.de ([195.135.220.15]:45072 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727035AbgA2SXD (ORCPT ); Wed, 29 Jan 2020 13:23:03 -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 861DFB2B2; Wed, 29 Jan 2020 18:23:01 +0000 (UTC) From: Davidlohr Bueso To: idryomov@gmail.com Cc: ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org, dave@stgolabs.net, Davidlohr Bueso Subject: [PATCH] rbd: optimize barrier usage for Rmw atomic bitops Date: Wed, 29 Jan 2020 10:12:53 -0800 Message-Id: <20200129181253.24999-1-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 For both set and clear_bit, we can avoid the unnecessary barrier on non LL/SC architectures, such as x86. Instead, use the smp_mb__{before,after}_atomic() calls. Signed-off-by: Davidlohr Bueso --- drivers/block/rbd.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 2b184563cd32..7bc79b2b8f65 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -1371,13 +1371,13 @@ static void rbd_osd_submit(struct ceph_osd_request *osd_req) static void img_request_layered_set(struct rbd_img_request *img_request) { set_bit(IMG_REQ_LAYERED, &img_request->flags); - smp_mb(); + smp_mb__after_atomic(); } static void img_request_layered_clear(struct rbd_img_request *img_request) { clear_bit(IMG_REQ_LAYERED, &img_request->flags); - smp_mb(); + smp_mb__after_atomic(); } static bool img_request_layered_test(struct rbd_img_request *img_request) -- 2.16.4