From patchwork Tue Sep 7 10:18:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tetsuo Handa X-Patchwork-Id: 12478227 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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 75C3CC433F5 for ; Tue, 7 Sep 2021 10:18:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 504AC610FE for ; Tue, 7 Sep 2021 10:18:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245475AbhIGKTa (ORCPT ); Tue, 7 Sep 2021 06:19:30 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:63922 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245525AbhIGKTQ (ORCPT ); Tue, 7 Sep 2021 06:19:16 -0400 Received: from fsav114.sakura.ne.jp (fsav114.sakura.ne.jp [27.133.134.241]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 187AI0QK099781; Tue, 7 Sep 2021 19:18:00 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav114.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav114.sakura.ne.jp); Tue, 07 Sep 2021 19:18:00 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav114.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 187AI0C0099777 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Tue, 7 Sep 2021 19:18:00 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: [PATCH v2] brd: reduce the brd_devices_mutex scope To: Jens Axboe Cc: linux-block , Christoph Hellwig References: <65b57a74-34db-d466-df67-c7a7bb529ae3@i-love.sakura.ne.jp> <20210907064958.GA29211@lst.de> From: Tetsuo Handa Message-ID: Date: Tue, 7 Sep 2021 19:18:00 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210907064958.GA29211@lst.de> Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org As with commit 8b52d8be86d72308 ("loop: reorder loop_exit"), unregister_blkdev() needs to be called first in order to avoid calling brd_alloc() from brd_probe() after brd_del_one() from brd_exit(). Then, we can avoid holding global mutex during add_disk()/del_gendisk() as with commit 1c500ad706383f1a ("loop: reduce the loop_ctl_mutex scope"). Signed-off-by: Tetsuo Handa Reviewed-by: Christoph Hellwig --- Changes in v2: s/brd->brd_number != i/brd->brd_number == i/ drivers/block/brd.c | 44 ++++++++++++++++++++++---------------------- 1 file changed, 22 insertions(+), 22 deletions(-) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index 58ec167aa018..530b31240203 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -373,10 +373,22 @@ static int brd_alloc(int i) struct gendisk *disk; char buf[DISK_NAME_LEN]; + mutex_lock(&brd_devices_mutex); + list_for_each_entry(brd, &brd_devices, brd_list) { + if (brd->brd_number == i) { + mutex_unlock(&brd_devices_mutex); + return -EEXIST; + } + } brd = kzalloc(sizeof(*brd), GFP_KERNEL); - if (!brd) + if (!brd) { + mutex_unlock(&brd_devices_mutex); return -ENOMEM; + } brd->brd_number = i; + list_add_tail(&brd->brd_list, &brd_devices); + mutex_unlock(&brd_devices_mutex); + spin_lock_init(&brd->brd_lock); INIT_RADIX_TREE(&brd->brd_pages, GFP_ATOMIC); @@ -411,37 +423,30 @@ static int brd_alloc(int i) blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue); blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, disk->queue); add_disk(disk); - list_add_tail(&brd->brd_list, &brd_devices); return 0; out_free_dev: + mutex_lock(&brd_devices_mutex); + list_del(&brd->brd_list); + mutex_unlock(&brd_devices_mutex); kfree(brd); return -ENOMEM; } static void brd_probe(dev_t dev) { - int i = MINOR(dev) / max_part; - struct brd_device *brd; - - mutex_lock(&brd_devices_mutex); - list_for_each_entry(brd, &brd_devices, brd_list) { - if (brd->brd_number == i) - goto out_unlock; - } - - brd_alloc(i); -out_unlock: - mutex_unlock(&brd_devices_mutex); + brd_alloc(MINOR(dev) / max_part); } static void brd_del_one(struct brd_device *brd) { - list_del(&brd->brd_list); del_gendisk(brd->brd_disk); blk_cleanup_disk(brd->brd_disk); brd_free_pages(brd); + mutex_lock(&brd_devices_mutex); + list_del(&brd->brd_list); + mutex_unlock(&brd_devices_mutex); kfree(brd); } @@ -491,25 +496,21 @@ static int __init brd_init(void) brd_debugfs_dir = debugfs_create_dir("ramdisk_pages", NULL); - mutex_lock(&brd_devices_mutex); for (i = 0; i < rd_nr; i++) { err = brd_alloc(i); if (err) goto out_free; } - mutex_unlock(&brd_devices_mutex); - pr_info("brd: module loaded\n"); return 0; out_free: + unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); debugfs_remove_recursive(brd_debugfs_dir); list_for_each_entry_safe(brd, next, &brd_devices, brd_list) brd_del_one(brd); - mutex_unlock(&brd_devices_mutex); - unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); pr_info("brd: module NOT loaded !!!\n"); return err; @@ -519,13 +520,12 @@ static void __exit brd_exit(void) { struct brd_device *brd, *next; + unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); debugfs_remove_recursive(brd_debugfs_dir); list_for_each_entry_safe(brd, next, &brd_devices, brd_list) brd_del_one(brd); - unregister_blkdev(RAMDISK_MAJOR, "ramdisk"); - pr_info("brd: module unloaded\n"); }