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=-10.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 CFABEC43441 for ; Mon, 26 Nov 2018 10:57:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 99A1920817 for ; Mon, 26 Nov 2018 10:57:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="MGCtzEFt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 99A1920817 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org 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 S1728867AbeKZVvS (ORCPT ); Mon, 26 Nov 2018 16:51:18 -0500 Received: from mail.kernel.org ([198.145.29.99]:60640 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726200AbeKZVvQ (ORCPT ); Mon, 26 Nov 2018 16:51:16 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B5D8320817; Mon, 26 Nov 2018 10:57:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1543229852; bh=e32PDZH/K5hk6uEO7HLK5+0vsDg1syEeFLQDFm5OAKI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MGCtzEFtKsdPv5hHQFFfydxTIEgG84V3SN3iaQI1Lsw5BinUbAg7fwrjYgufZ3o14 9G9vCQu+YXN+0dVFN1bgRVJupZoTe04NXQ1uNs52i0Klc98G2qLKXGkhokfMffcc1x L5GLmGNrUDj0wS062PVVwsbrR6Wc9GEosGUZlYF8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sergey Senozhatsky , Hannes Reinecke , Howard Chen , Minchan Kim , Sasha Levin Subject: [PATCH 4.9 25/46] zram: close udev startup race condition as default groups Date: Mon, 26 Nov 2018 11:51:14 +0100 Message-Id: <20181126105048.552195863@linuxfoundation.org> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181126105045.447291262@linuxfoundation.org> References: <20181126105045.447291262@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ commit fef912bf860e upstream. commit 98af4d4df889 upstream. I got a report from Howard Chen that he saw zram and sysfs race(ie, zram block device file is created but sysfs for it isn't yet) when he tried to create new zram devices via hotadd knob. v4.20 kernel fixes it by [1, 2] but it's too large size to merge into -stable so this patch fixes the problem by registering defualt group by Greg KH's approach[3]. This patch should be applied to every stable tree [3.16+] currently existing from kernel.org because the problem was introduced at 2.6.37 by [4]. [1] fef912bf860e, block: genhd: add 'groups' argument to device_add_disk [2] 98af4d4df889, zram: register default groups with device_add_disk() [3] http://kroah.com/log/blog/2013/06/26/how-to-create-a-sysfs-file-correctly/ [4] 33863c21e69e9, Staging: zram: Replace ioctls with sysfs interface Cc: Sergey Senozhatsky Cc: Hannes Reinecke Tested-by: Howard Chen Signed-off-by: Minchan Kim Signed-off-by: Sasha Levin --- drivers/block/zram/zram_drv.c | 26 ++++++-------------------- 1 file changed, 6 insertions(+), 20 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index b7c0b69a02f5..d64a53d3270a 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1223,6 +1223,11 @@ static struct attribute_group zram_disk_attr_group = { .attrs = zram_disk_attrs, }; +static const struct attribute_group *zram_disk_attr_groups[] = { + &zram_disk_attr_group, + NULL, +}; + /* * Allocate and initialize new zram device. the function returns * '>= 0' device_id upon success, and negative value otherwise. @@ -1303,24 +1308,15 @@ static int zram_add(void) zram->disk->queue->limits.discard_zeroes_data = 0; queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue); + disk_to_dev(zram->disk)->groups = zram_disk_attr_groups; add_disk(zram->disk); - ret = sysfs_create_group(&disk_to_dev(zram->disk)->kobj, - &zram_disk_attr_group); - if (ret < 0) { - pr_err("Error creating sysfs group for device %d\n", - device_id); - goto out_free_disk; - } strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor)); zram->meta = NULL; pr_info("Added device: %s\n", zram->disk->disk_name); return device_id; -out_free_disk: - del_gendisk(zram->disk); - put_disk(zram->disk); out_free_queue: blk_cleanup_queue(queue); out_free_idr: @@ -1348,16 +1344,6 @@ static int zram_remove(struct zram *zram) zram->claim = true; mutex_unlock(&bdev->bd_mutex); - /* - * Remove sysfs first, so no one will perform a disksize - * store while we destroy the devices. This also helps during - * hot_remove -- zram_reset_device() is the last holder of - * ->init_lock, no later/concurrent disksize_store() or any - * other sysfs handlers are possible. - */ - sysfs_remove_group(&disk_to_dev(zram->disk)->kobj, - &zram_disk_attr_group); - /* Make sure all the pending I/O are finished */ fsync_bdev(bdev); zram_reset_device(zram); -- 2.17.1