From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932953AbaJVUO0 (ORCPT ); Wed, 22 Oct 2014 16:14:26 -0400 Received: from cantor2.suse.de ([195.135.220.15]:47027 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932841AbaJVUOU (ORCPT ); Wed, 22 Oct 2014 16:14:20 -0400 From: Jan Kara To: Al Viro Cc: hch@lst.de, linux-fsdevel@vger.kernel.org, LKML , Jan Kara Subject: [PATCH 2/4] chardev: Increment cdev reference count when i_cdev references it Date: Wed, 22 Oct 2014 22:14:11 +0200 Message-Id: <1414008853-13200-3-git-send-email-jack@suse.cz> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1414008853-13200-1-git-send-email-jack@suse.cz> References: <1414008853-13200-1-git-send-email-jack@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently i_cdev reference to a character device isn't accounted in the reference count of the character device. This then requires us to track all references through a list of all inodes referencing a character device which is somewhat clumsy and requires list_head in each inode in the system. So make i_cdev a reference like any other. Signed-off-by: Jan Kara --- fs/char_dev.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/fs/char_dev.c b/fs/char_dev.c index f77f7702fabe..21c210dbdba1 100644 --- a/fs/char_dev.c +++ b/fs/char_dev.c @@ -388,12 +388,13 @@ static int chrdev_open(struct inode *inode, struct file *filp) we dropped the lock. */ p = inode->i_cdev; if (!p) { + /* Use reference from kobj_lookup for i_cdev ref */ inode->i_cdev = p = new; list_add(&inode->i_devices, &p->list); new = NULL; - } else if (!cdev_get(p)) - ret = -ENXIO; - } else if (!cdev_get(p)) + } + } + if (!cdev_get(p)) ret = -ENXIO; spin_unlock(&cdev_lock); cdev_put(new); @@ -421,10 +422,15 @@ static int chrdev_open(struct inode *inode, struct file *filp) void cd_forget(struct inode *inode) { + struct cdev *cdev; + spin_lock(&cdev_lock); list_del_init(&inode->i_devices); + cdev = inode->i_cdev; inode->i_cdev = NULL; spin_unlock(&cdev_lock); + if (cdev) + cdev_put(cdev); } static void cdev_purge(struct cdev *cdev) -- 1.8.1.4