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 18FFBC433EF for ; Wed, 11 May 2022 06:34:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235384AbiEKGeo (ORCPT ); Wed, 11 May 2022 02:34:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34472 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232428AbiEKGen (ORCPT ); Wed, 11 May 2022 02:34:43 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23CF8239B11; Tue, 10 May 2022 23:34:42 -0700 (PDT) Received: from dggpemm500024.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KylVd3ldFzhZ4p; Wed, 11 May 2022 14:34:01 +0800 (CST) Received: from [10.174.179.0] (10.174.179.0) by dggpemm500024.china.huawei.com (7.185.36.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 11 May 2022 14:34:40 +0800 Message-ID: Date: Wed, 11 May 2022 14:34:28 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 To: CC: , , , , From: "zhanghongtao (A)" Subject: [PATCH] drivers:uio: Fix system crashes during driver switchover Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.179.0] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemm500024.china.huawei.com (7.185.36.203) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org From: Hongtao Zhang Switch the driver of the SPDK program that is being read and written from the uio_pci_generic driver to the NVMe driver (Unbind the UIO driver from the device and bind the NVMe driver to the device.) ,the system crashes and restarts. Bug reproduction: When the SPDK is reading or writing data, run the following command: /opt/spdk/setup.sh reset The one with a higher probability of occurrence is as follows: PANIC: "BUG: unable to handle kernel NULL pointer dereference at 0000000000000008" [exception RIP: _raw_spin_lock_irqsave+30] RIP: ffffffff836a1cae RSP: ffff8bca9ecc3f20 RFLAGS: 00010046 RAX: 0000000000000000 RBX: 0000000000000246 RCX: 0000000000000017 RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000008 RBP: 0000000000000000 R8: 000000afb34e50f9 R9: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8bca9ecc3f50 R13: 0000000000000004 R14: 0000000000000004 R15: 0000000000000000 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 #7 [ffff8bca9ecc3f28] complete at ffffffff82f09bb8 reason:After the driver switchover, the upper-layer program can still access the bar space of the NVMe disk controller and knock the doorbell. To solve this problem, a reference counting is added to prevent unbind execution before the application is closed or exited. Signed-off-by: Hongtao Zhang Reviewed-by: Weifeng Su --- drivers/uio/uio.c | 13 +++++++++++++ include/linux/uio_driver.h | 1 + 2 files changed, 14 insertions(+) diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index 43afbb7c5ab9..cb8ed29a8648 100644 --- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c @@ -31,6 +31,7 @@ static int uio_major; static struct cdev *uio_cdev; static DEFINE_IDR(uio_idr); static const struct file_operations uio_fops; +static DECLARE_WAIT_QUEUE_HEAD(refc_wait); /* Protect idr accesses */ static DEFINE_MUTEX(minor_lock); @@ -501,6 +502,7 @@ static int uio_open(struct inode *inode, struct file *filep) mutex_unlock(&idev->info_lock); if (ret) goto err_infoopen; + refcount_inc(&idev->dev_refc); return 0; @@ -536,6 +538,9 @@ static int uio_release(struct inode *inode, struct file *filep) ret = idev->info->release(idev->info, inode); mutex_unlock(&idev->info_lock); + if (refcount_dec_and_test(&idev->dev_refc)) + wake_up(&refc_wait); + module_put(idev->owner); kfree(listener); put_device(&idev->dev); @@ -937,6 +942,7 @@ int __uio_register_device(struct module *owner, idev->owner = owner; idev->info = info; + refcount_set(&idev->dev_refc, 0); mutex_init(&idev->info_lock); init_waitqueue_head(&idev->wait); atomic_set(&idev->event, 0); @@ -1045,6 +1051,7 @@ void uio_unregister_device(struct uio_info *info) { struct uio_device *idev; unsigned long minor; + unsigned int dref_count; if (!info || !info->uio_dev) return; @@ -1052,6 +1059,12 @@ void uio_unregister_device(struct uio_info *info) idev = info->uio_dev; minor = idev->minor; + dref_count = refcount_read(&idev->dev_refc); + if (dref_count > 0) { + dev_err(&idev->dev, "The device is in use, please close the file descriptor or kill the occupied process\n"); + wait_event(refc_wait, !refcount_read(&idev->dev_refc)); + } + mutex_lock(&idev->info_lock); uio_dev_del_attributes(idev); diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h index 47c5962b876b..28301dcc4d31 100644 --- a/include/linux/uio_driver.h +++ b/include/linux/uio_driver.h @@ -77,6 +77,7 @@ struct uio_device { struct mutex info_lock; struct kobject *map_dir; struct kobject *portio_dir; + refcount_t dev_refc; }; /** -- 2.27.0