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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2757C4167E for ; Mon, 15 Nov 2021 20:53:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CA064611BF for ; Mon, 15 Nov 2021 20:53:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353295AbhKOUze (ORCPT ); Mon, 15 Nov 2021 15:55:34 -0500 Received: from mail.kernel.org ([198.145.29.99]:50070 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240641AbhKOSLd (ORCPT ); Mon, 15 Nov 2021 13:11:33 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 192DE633C2; Mon, 15 Nov 2021 17:47:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636998454; bh=hRgGveg67O4YaQdaBJBoise6YYevgIu8X342+sr0c6I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=g5Ry6F4KxbcYMX6MsTqZ46d6plKaL2ts8TFJOHipfGCe5qoL1VXIWNN2OmCvU5niw 2Q+5sKQ4HPTFOdQhS3t1gOM7bifIKQ6N/Q1xifQNQ5F/bi9/HMV2YJZF2s4XAcrSO9 Df7ofwedP8xmIKxYLsRlWPPkQfgqIZgy4dCWavtE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tetsuo Handa , Luis Chamberlain , Michael Schmitz , Jens Axboe , Sasha Levin Subject: [PATCH 5.10 516/575] ataflop: remove ataflop_probe_lock mutex Date: Mon, 15 Nov 2021 18:04:01 +0100 Message-Id: <20211115165401.523895690@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165343.579890274@linuxfoundation.org> References: <20211115165343.579890274@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tetsuo Handa [ Upstream commit 4ddb85d36613c45bde00d368bf9f357bd0708a0c ] Commit bf9c0538e485b591 ("ataflop: use a separate gendisk for each media format") introduced ataflop_probe_lock mutex, but forgot to unlock the mutex when atari_floppy_init() (i.e. module loading) succeeded. This will result in double lock deadlock if ataflop_probe() is called. Also, unregister_blkdev() must not be called from atari_floppy_init() with ataflop_probe_lock held when atari_floppy_init() failed, for ataflop_probe() waits for ataflop_probe_lock with major_names_lock held (i.e. AB-BA deadlock). __register_blkdev() needs to be called last in order to avoid calling ataflop_probe() when atari_floppy_init() is about to fail, for memory for completing already-started ataflop_probe() safely will be released as soon as atari_floppy_init() released ataflop_probe_lock mutex. As with commit 8b52d8be86d72308 ("loop: reorder loop_exit"), unregister_blkdev() needs to be called first in order to avoid calling ataflop_alloc_disk() from ataflop_probe() after del_gendisk() from atari_floppy_exit(). By relocating __register_blkdev() / unregister_blkdev() as explained above, we can remove ataflop_probe_lock mutex, for probe function and __exit function are serialized by major_names_lock mutex. Signed-off-by: Tetsuo Handa Fixes: bf9c0538e485b591 ("ataflop: use a separate gendisk for each media format") Reviewed-by: Luis Chamberlain Tested-by: Michael Schmitz Link: https://lore.kernel.org/r/20211103230437.1639990-11-mcgrof@kernel.org Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/ataflop.c | 47 +++++++++++++++++++++++------------------ 1 file changed, 27 insertions(+), 20 deletions(-) diff --git a/drivers/block/ataflop.c b/drivers/block/ataflop.c index 2d3a66362dcf9..3a29f1992d971 100644 --- a/drivers/block/ataflop.c +++ b/drivers/block/ataflop.c @@ -2016,8 +2016,6 @@ static int ataflop_alloc_disk(unsigned int drive, unsigned int type) return 0; } -static DEFINE_MUTEX(ataflop_probe_lock); - static void ataflop_probe(dev_t dev) { int drive = MINOR(dev) & 3; @@ -2025,14 +2023,32 @@ static void ataflop_probe(dev_t dev) if (drive >= FD_MAX_UNITS || type > NUM_DISK_MINORS) return; - mutex_lock(&ataflop_probe_lock); if (!unit[drive].disk[type]) { if (ataflop_alloc_disk(drive, type) == 0) { add_disk(unit[drive].disk[type]); unit[drive].registered[type] = true; } } - mutex_unlock(&ataflop_probe_lock); +} + +static void atari_floppy_cleanup(void) +{ + int i; + int type; + + for (i = 0; i < FD_MAX_UNITS; i++) { + for (type = 0; type < NUM_DISK_MINORS; type++) { + if (!unit[i].disk[type]) + continue; + del_gendisk(unit[i].disk[type]); + blk_cleanup_queue(unit[i].disk[type]->queue); + put_disk(unit[i].disk[type]); + } + blk_mq_free_tag_set(&unit[i].tag_set); + } + + del_timer_sync(&fd_timer); + atari_stram_free(DMABuffer); } static void atari_cleanup_floppy_disk(struct atari_floppy_struct *fs) @@ -2058,11 +2074,6 @@ static int __init atari_floppy_init (void) /* Amiga, Mac, ... don't have Atari-compatible floppy :-) */ return -ENODEV; - mutex_lock(&ataflop_probe_lock); - ret = __register_blkdev(FLOPPY_MAJOR, "fd", ataflop_probe); - if (ret) - goto out_unlock; - for (i = 0; i < FD_MAX_UNITS; i++) { memset(&unit[i].tag_set, 0, sizeof(unit[i].tag_set)); unit[i].tag_set.ops = &ataflop_mq_ops; @@ -2116,15 +2127,17 @@ static int __init atari_floppy_init (void) UseTrackbuffer ? "" : "no "); config_types(); - return 0; + ret = __register_blkdev(FLOPPY_MAJOR, "fd", ataflop_probe); + if (ret) { + printk(KERN_ERR "atari_floppy_init: cannot register block device\n"); + atari_floppy_cleanup(); + } + return ret; err: while (--i >= 0) atari_cleanup_floppy_disk(&unit[i]); - unregister_blkdev(FLOPPY_MAJOR, "fd"); -out_unlock: - mutex_unlock(&ataflop_probe_lock); return ret; } @@ -2169,14 +2182,8 @@ __setup("floppy=", atari_floppy_setup); static void __exit atari_floppy_exit(void) { - int i; - - for (i = 0; i < FD_MAX_UNITS; i++) - atari_cleanup_floppy_disk(&unit[i]); unregister_blkdev(FLOPPY_MAJOR, "fd"); - - del_timer_sync(&fd_timer); - atari_stram_free( DMABuffer ); + atari_floppy_cleanup(); } module_init(atari_floppy_init) -- 2.33.0