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 00565C433F5 for ; Thu, 7 Apr 2022 17:22:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346121AbiDGRYL (ORCPT ); Thu, 7 Apr 2022 13:24:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346071AbiDGRXz (ORCPT ); Thu, 7 Apr 2022 13:23:55 -0400 Received: from ale.deltatee.com (ale.deltatee.com [204.191.154.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C1380BE08; Thu, 7 Apr 2022 10:21:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:MIME-Version:References:In-Reply-To: Message-Id:Date:Cc:To:From:content-disposition; bh=635ylQUcdfFmtEy7PfYRtKd/q8+5RGAxrk1aQwRlsw8=; b=PzXQRQYpXdXhwt9mfTGGsdnyJz l0BTLXXaGHofw2ZqsBOF7SczKDAW+vTZzKlHQinURnmsNceWmWlSSy6xK8dCOTdA4dReoI3ZaTwe5 whstDVfyrbkTNi2b3ycXVvkM/6RRecLsobqgJl9Q5ZWuuSTErhuTFXCbEZFIAZTcPU+BWZ4O3qShp 7PAkXTLp1UjrnzfEOFMMbLg09XP/LUbsZwx/j79QQQMxjBFrw/dZGtMuorww51II/7Qju2ltmyiH9 SPdif6fNoXFELntKTQmXINf9ZvM7uxbjHEn6E1o1xJ6bwhEcp/L52LDzTfPLuVwibdw1aNg3Ujtgh l6RzzhTg==; Received: from cgy1-donard.priv.deltatee.com ([172.16.1.31]) by ale.deltatee.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1ncVRf-002CRm-Ow; Thu, 07 Apr 2022 10:57:22 -0600 Received: from gunthorp by cgy1-donard.priv.deltatee.com with local (Exim 4.94.2) (envelope-from ) id 1ncVRf-0002QA-Aw; Thu, 07 Apr 2022 10:57:19 -0600 From: Logan Gunthorpe To: linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, Song Liu Cc: Guoqing Jiang , Logan Gunthorpe Date: Thu, 7 Apr 2022 10:57:10 -0600 Message-Id: <20220407165713.9243-5-logang@deltatee.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220407165713.9243-1-logang@deltatee.com> References: <20220407165713.9243-1-logang@deltatee.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 172.16.1.31 X-SA-Exim-Rcpt-To: linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, song@kernel.org, guoqing.jiang@linux.dev, logang@deltatee.com X-SA-Exim-Mail-From: gunthorp@deltatee.com Subject: [PATCH v1 4/7] md/raid5: Annotate rdev/replacement accesses when nr_pending is elevated X-SA-Exim-Version: 4.2.1 (built Sat, 13 Feb 2021 17:57:42 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There are a number of accesses to __rcu variables that should be safe because nr_pending in the disk is known to be elevated. Create a wrapper around rcu_dereference_protected() to annotate these accesses and verify that nr_pending is non-zero. This fixes a number of sparse warnings. Signed-off-by: Logan Gunthorpe --- drivers/md/raid5.c | 28 +++++++++++++++++++--------- 1 file changed, 19 insertions(+), 9 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 4815f5351818..0f29a2769cb3 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -2648,6 +2648,16 @@ static void shrink_stripes(struct r5conf *conf) conf->slab_cache = NULL; } +/* + * This helper wraps rcu_dereference_protected() and can be used when + * it is known that the nr_pending of the rdev is elevated. + */ +static struct md_rdev *rdev_pend_deref(struct md_rdev __rcu *rdev) +{ + return rcu_dereference_protected(rdev, + atomic_read(&rcu_access_pointer(rdev)->nr_pending)); +} + static void raid5_end_read_request(struct bio * bi) { struct stripe_head *sh = bi->bi_private; @@ -2674,9 +2684,9 @@ static void raid5_end_read_request(struct bio * bi) * In that case it moved down to 'rdev'. * rdev is not removed until all requests are finished. */ - rdev = conf->disks[i].replacement; + rdev = rdev_pend_deref(conf->disks[i].replacement); if (!rdev) - rdev = conf->disks[i].rdev; + rdev = rdev_pend_deref(conf->disks[i].rdev); if (use_new_offset(conf, sh)) s = sh->sector + rdev->new_data_offset; @@ -2790,11 +2800,11 @@ static void raid5_end_write_request(struct bio *bi) for (i = 0 ; i < disks; i++) { if (bi == &sh->dev[i].req) { - rdev = conf->disks[i].rdev; + rdev = rdev_pend_deref(conf->disks[i].rdev); break; } if (bi == &sh->dev[i].rreq) { - rdev = conf->disks[i].replacement; + rdev = rdev_pend_deref(conf->disks[i].replacement); if (rdev) replacement = 1; else @@ -2802,7 +2812,7 @@ static void raid5_end_write_request(struct bio *bi) * replaced it. rdev is not removed * until all requests are finished. */ - rdev = conf->disks[i].rdev; + rdev = rdev_pend_deref(conf->disks[i].rdev); break; } } @@ -5213,23 +5223,23 @@ static void handle_stripe(struct stripe_head *sh) struct r5dev *dev = &sh->dev[i]; if (test_and_clear_bit(R5_WriteError, &dev->flags)) { /* We own a safe reference to the rdev */ - rdev = conf->disks[i].rdev; + rdev = rdev_pend_deref(conf->disks[i].rdev); if (!rdev_set_badblocks(rdev, sh->sector, RAID5_STRIPE_SECTORS(conf), 0)) md_error(conf->mddev, rdev); rdev_dec_pending(rdev, conf->mddev); } if (test_and_clear_bit(R5_MadeGood, &dev->flags)) { - rdev = conf->disks[i].rdev; + rdev = rdev_pend_deref(conf->disks[i].rdev); rdev_clear_badblocks(rdev, sh->sector, RAID5_STRIPE_SECTORS(conf), 0); rdev_dec_pending(rdev, conf->mddev); } if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) { - rdev = conf->disks[i].replacement; + rdev = rdev_pend_deref(conf->disks[i].replacement); if (!rdev) /* rdev have been moved down */ - rdev = conf->disks[i].rdev; + rdev = rdev_pend_deref(conf->disks[i].rdev); rdev_clear_badblocks(rdev, sh->sector, RAID5_STRIPE_SECTORS(conf), 0); rdev_dec_pending(rdev, conf->mddev); -- 2.30.2