From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422729Ab2LFWZz (ORCPT ); Thu, 6 Dec 2012 17:25:55 -0500 Received: from www.hansjkoch.de ([178.63.77.200]:51533 "EHLO www.hansjkoch.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755682Ab2LFWZy (ORCPT ); Thu, 6 Dec 2012 17:25:54 -0500 Date: Thu, 6 Dec 2012 23:25:53 +0100 From: "Hans J. Koch" To: Benedikt Spranger Cc: linux-kernel@vger.kernel.org, hjk@hansjkoch.de, gregkh@linuxfoundation.org, Alexander.Frank@eberspaecher.com Subject: Re: [PATCH 2/2] uio: avoid module unloding of in module created UIO devices Message-ID: <20121206222552.GC2611@local> References: <1354797897-23423-1-git-send-email-b.spranger@linutronix.de> <1354797897-23423-3-git-send-email-b.spranger@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1354797897-23423-3-git-send-email-b.spranger@linutronix.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 06, 2012 at 01:44:57PM +0100, Benedikt Spranger wrote: > A kernel module can create a uio device. Get a reference to the module, if the > UIO device is in use. Otherwise the device can be removed and a uio write or an > access to am mmaped memory can cause a kernel Oops or other strange effects. > > Signed-off-by: Benedikt Spranger > --- > drivers/uio/uio.c | 8 ++++++++ > include/linux/uio_driver.h | 1 + > 2 files changed, 9 insertions(+) > > diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c > index b96499a..3b62da0 100644 > --- a/drivers/uio/uio.c > +++ b/drivers/uio/uio.c > @@ -446,6 +446,7 @@ static void uio_release_listener(struct kref *kref) > idev->info->release(idev->info); > > module_put(idev->owner); > + module_put(idev->info->owner); > kfree(listener); > } > > @@ -468,6 +469,11 @@ static int uio_open(struct inode *inode, struct file *filep) > goto out; > } > > + if (!try_module_get(idev->info->owner)) { > + ret = -ENODEV; > + goto err_get_module; > + } > + > listener = kmalloc(sizeof(*listener), GFP_KERNEL); > if (!listener) { > ret = -ENOMEM; > @@ -493,6 +499,8 @@ err_infoopen: > > err_alloc_listener: > module_put(idev->owner); > +err_get_module: > + module_put(idev->owner); > > out: > return ret; > diff --git a/include/linux/uio_driver.h b/include/linux/uio_driver.h > index 1bc6493..2862de23 100644 > --- a/include/linux/uio_driver.h > +++ b/include/linux/uio_driver.h > @@ -95,6 +95,7 @@ struct uio_info { > int (*open)(struct uio_info *info); > void (*release)(struct uio_info *info); > int (*irqcontrol)(struct uio_info *info, s32 irq_on); > + struct module *owner; Where is that needed? I won't add a new element to struct uio_info without an in-kernel user. Thanks, Hans