From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755860AbdDPJxI (ORCPT ); Sun, 16 Apr 2017 05:53:08 -0400 Received: from mail-wr0-f196.google.com ([209.85.128.196]:35879 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932151AbdDPJv7 (ORCPT ); Sun, 16 Apr 2017 05:51:59 -0400 From: Nicolai Stange To: Greg Kroah-Hartman Cc: Johannes Berg , "Paul E.McKenney" , Nicolai Stange , linux-kernel@vger.kernel.org Subject: [RFC PATCH 7/9] debugfs: call debugfs_real_fops() only after debugfs_file_get() Date: Sun, 16 Apr 2017 11:51:35 +0200 Message-Id: <20170416095137.2784-8-nicstange@gmail.com> X-Mailer: git-send-email 2.12.2 In-Reply-To: <20170416095137.2784-1-nicstange@gmail.com> References: <871stdyg0u.fsf@gmail.com> <20170416095137.2784-1-nicstange@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The current implementation of debugfs_real_fops() relies on a debugfs_fsdata instance to be installed at ->d_fsdata. With future patches introducing lazy allocation of these, this requirement will be guaranteed to be fullfilled only inbetween a debugfs_file_get()/debugfs_file_put() pair. The full proxies' fops implemented by debugfs happen to be the only offenders. Fix them up by moving their debugfs_real_fops() calls past those to debugfs_file_get(). full_proxy_release() is special as it doesn't invoke debugfs_file_get() at all. Leave it alone for now. Signed-off-by: Nicolai Stange --- fs/debugfs/file.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index 7de733ccdf6c..d92038c5f131 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -144,13 +144,13 @@ const struct file_operations debugfs_open_proxy_file_operations = { static ret_type full_proxy_ ## name(proto) \ { \ struct dentry *dentry = F_DENTRY(filp); \ - const struct file_operations *real_fops = \ - debugfs_real_fops(filp); \ + const struct file_operations *real_fops; \ ret_type r; \ \ r = debugfs_file_get(dentry); \ if (unlikely(r)) \ return r; \ + real_fops = debugfs_real_fops(filp); \ r = real_fops->name(args); \ debugfs_file_put(dentry); \ return r; \ @@ -177,13 +177,14 @@ FULL_PROXY_FUNC(unlocked_ioctl, long, filp, static unsigned int full_proxy_poll(struct file *filp, struct poll_table_struct *wait) { - const struct file_operations *real_fops = debugfs_real_fops(filp); struct dentry *dentry = F_DENTRY(filp); unsigned int r = 0; + const struct file_operations *real_fops; if (debugfs_file_get(dentry)) return POLLHUP; + real_fops = debugfs_real_fops(filp); r = real_fops->poll(filp, wait); debugfs_file_put(dentry); return r; -- 2.12.2