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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 27F00C32771 for ; Sun, 18 Sep 2022 11:36:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229681AbiIRLgj (ORCPT ); Sun, 18 Sep 2022 07:36:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229519AbiIRLgi (ORCPT ); Sun, 18 Sep 2022 07:36:38 -0400 Received: from out2.migadu.com (out2.migadu.com [IPv6:2001:41d0:2:aacc::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 976F8EE1D; Sun, 18 Sep 2022 04:36:37 -0700 (PDT) Subject: Re: [PATCH v3 5/5] md/raid10: convert resync_lock to use seqlock DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1663500995; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=G1+OGv4dFkBOVxp4OCIgge5yTXIRZosYR+jSx6W73rc=; b=G5FN5C8jAtDshvH1MV2Mrx/CW3u8FueyfS4Ure/+AfV2vocdKjXUmQEpPO4gz5CN4f9XSZ qxPQ1YFb3QjsTm4G1vTjrI3h0lkAyYyXU1GgjenX9xxUDvrQfNVF/UfBwCogqsIDw8yBcK ho1s6e21EsPpB3+fYL6h8v+vq7w9+ws= To: Yu Kuai , song@kernel.org, logang@deltatee.com, pmenzel@molgen.mpg.de Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yi.zhang@huawei.com References: <20220916113428.774061-1-yukuai1@huaweicloud.com> <20220916113428.774061-6-yukuai1@huaweicloud.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Guoqing Jiang Message-ID: Date: Sun, 18 Sep 2022 19:36:26 +0800 MIME-Version: 1.0 In-Reply-To: <20220916113428.774061-6-yukuai1@huaweicloud.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On 9/16/22 7:34 PM, Yu Kuai wrote: > From: Yu Kuai > > Currently, wait_barrier() will hold 'resync_lock' to read 'conf->barrier', > and io can't be dispatched until 'barrier' is dropped. > > Since holding the 'barrier' is not common, convert 'resync_lock' to use > seqlock so that holding lock can be avoided in fast path. > > Signed-off-by: Yu Kuai > --- > drivers/md/raid10.c | 87 ++++++++++++++++++++++++++++++--------------- > drivers/md/raid10.h | 2 +- > 2 files changed, 59 insertions(+), 30 deletions(-) > > diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c > index 9a28abd19709..2daa7d57034c 100644 > --- a/drivers/md/raid10.c > +++ b/drivers/md/raid10.c > @@ -79,6 +79,21 @@ static void end_reshape(struct r10conf *conf); > > #include "raid1-10.c" > > +#define NULL_CMD > +#define cmd_before(conf, cmd) \ > + do { \ > + write_sequnlock_irq(&(conf)->resync_lock); \ > + cmd; \ > + } while (0) > +#define cmd_after(conf) write_seqlock_irq(&(conf)->resync_lock) The two is not paired well given only cmd_before needs the 'cmd'. > + > +#define wait_event_barrier_cmd(conf, cond, cmd) \ > + wait_event_cmd((conf)->wait_barrier, cond, cmd_before(conf, cmd), \ > + cmd_after(conf)) > + > +#define wait_event_barrier(conf, cond) \ > + wait_event_barrier_cmd(conf, cond, NULL_CMD) What is the issue without define NULL_CMD? Thanks, Guoqing