From patchwork Fri Dec 17 11:03:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tetsuo Handa X-Patchwork-Id: 12684253 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 AC9E2C433F5 for ; Fri, 17 Dec 2021 11:03:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232148AbhLQLD5 (ORCPT ); Fri, 17 Dec 2021 06:03:57 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:60102 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235218AbhLQLD4 (ORCPT ); Fri, 17 Dec 2021 06:03:56 -0500 Received: from fsav415.sakura.ne.jp (fsav415.sakura.ne.jp [133.242.250.114]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 1BHB3nga015547; Fri, 17 Dec 2021 20:03:49 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav415.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav415.sakura.ne.jp); Fri, 17 Dec 2021 20:03:49 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav415.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 1BHB3mvd015544 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Fri, 17 Dec 2021 20:03:48 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Message-ID: <01fb7a16-fb97-b0e4-1c1f-aa42e7f68766@i-love.sakura.ne.jp> Date: Fri, 17 Dec 2021 20:03:48 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Content-Language: en-US To: Christoph Hellwig , Luis Chamberlain Cc: linux-block From: Tetsuo Handa Subject: [PATCH (resend)] brd: remove brd_devices_mutex mutex Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org If brd_alloc() from brd_probe() is called before brd_alloc() from brd_init() is called, module loading will fail with -EEXIST error. To close this race, call __register_blkdev() just before leaving brd_init(). Then, we can remove brd_devices_mutex mutex, for brd_device list will no longer be accessed concurrently. Signed-off-by: Tetsuo Handa Reviewed-by: Luis Chamberlain Reviewed-by: Christoph Hellwig --- drivers/block/brd.c | 73 +++++++++++++++++++-------------------------- 1 file changed, 30 insertions(+), 43 deletions(-) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index a896ee175d86..4aab5ed21ae8 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -362,7 +362,6 @@ __setup("ramdisk_size=", ramdisk_size); * (should share code eventually). */ static LIST_HEAD(brd_devices); -static DEFINE_MUTEX(brd_devices_mutex); static struct dentry *brd_debugfs_dir; static int brd_alloc(int i) @@ -372,21 +371,14 @@ static int brd_alloc(int i) char buf[DISK_NAME_LEN]; int err = -ENOMEM; - mutex_lock(&brd_devices_mutex); - list_for_each_entry(brd, &brd_devices, brd_list) { - if (brd->brd_number == i) { - mutex_unlock(&brd_devices_mutex); + list_for_each_entry(brd, &brd_devices, brd_list) + if (brd->brd_number == i) return -EEXIST; - } - } brd = kzalloc(sizeof(*brd), GFP_KERNEL); - if (!brd) { - mutex_unlock(&brd_devices_mutex); + if (!brd) 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); @@ -430,9 +422,7 @@ static int brd_alloc(int i) out_cleanup_disk: blk_cleanup_disk(disk); out_free_dev: - mutex_lock(&brd_devices_mutex); list_del(&brd->brd_list); - mutex_unlock(&brd_devices_mutex); kfree(brd); return err; } @@ -442,15 +432,19 @@ static void brd_probe(dev_t dev) brd_alloc(MINOR(dev) / max_part); } -static void brd_del_one(struct brd_device *brd) +static void brd_cleanup(void) { - 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); + struct brd_device *brd, *next; + + debugfs_remove_recursive(brd_debugfs_dir); + + list_for_each_entry_safe(brd, next, &brd_devices, brd_list) { + del_gendisk(brd->brd_disk); + blk_cleanup_disk(brd->brd_disk); + brd_free_pages(brd); + list_del(&brd->brd_list); + kfree(brd); + } } static inline void brd_check_and_reset_par(void) @@ -474,9 +468,18 @@ static inline void brd_check_and_reset_par(void) static int __init brd_init(void) { - struct brd_device *brd, *next; int err, i; + brd_check_and_reset_par(); + + brd_debugfs_dir = debugfs_create_dir("ramdisk_pages", NULL); + + for (i = 0; i < rd_nr; i++) { + err = brd_alloc(i); + if (err) + goto out_free; + } + /* * brd module now has a feature to instantiate underlying device * structure on-demand, provided that there is an access dev node. @@ -492,28 +495,16 @@ static int __init brd_init(void) * dynamically. */ - if (__register_blkdev(RAMDISK_MAJOR, "ramdisk", brd_probe)) - return -EIO; - - brd_check_and_reset_par(); - - brd_debugfs_dir = debugfs_create_dir("ramdisk_pages", NULL); - - for (i = 0; i < rd_nr; i++) { - err = brd_alloc(i); - if (err) - goto out_free; + if (__register_blkdev(RAMDISK_MAJOR, "ramdisk", brd_probe)) { + err = -EIO; + goto out_free; } 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); + brd_cleanup(); pr_info("brd: module NOT loaded !!!\n"); return err; @@ -521,13 +512,9 @@ static int __init brd_init(void) 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); + brd_cleanup(); pr_info("brd: module unloaded\n"); }