From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933108AbcE0SEJ (ORCPT ); Fri, 27 May 2016 14:04:09 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:33607 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933070AbcE0SEH (ORCPT ); Fri, 27 May 2016 14:04:07 -0400 From: Nicolai Stange To: Greg Kroah-Hartman Cc: Gustavo Padovan , =?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= , Riley Andrews , devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, Nicolai Stange Subject: [PATCH] staging/android: sync_debug: unproxify debugfs files' fops Date: Fri, 27 May 2016 20:03:54 +0200 Message-Id: <1464372234-13431-1-git-send-email-nicstange@gmail.com> X-Mailer: git-send-email 2.8.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since commit 49d200deaa68 ("debugfs: prevent access to removed files' private data"), a debugfs file's file_operations methods get proxied through lifetime aware wrappers. However, only a certain subset of the file_operations members is supported by debugfs and ->compat_ioctl isn't among them -- it appears to be NULL from the VFS layer's perspective. This behaviour breaks the /sys/kernel/debug/sync/sw_sync file introduced concurrently with commit a44eb74cd413 ("staging/android: move SW_SYNC_USER to a debugfs file"). Since that file never gets removed, there is no file removal race and thus, a lifetime checking proxy isn't needed. Avoid the proxying for /sys/kernel/debug/sync/sw_sync by creating it via debugfs_create_file_unsafe() rather than debugfs_create_file(). For consistency, do the same for /sys/kernel/debug/sync/info. Fixes: 49d200deaa68 ("debugfs: prevent access to removed files' private data") Fixes: a44eb74cd413 ("staging/android: move SW_SYNC_USER to a debugfs file") Signed-off-by: Nicolai Stange --- Applicable to linux-next-20160527. x86_64 allmodconfig build succeeds w/o any new warnings. Related discussion can be found here: http://lkml.kernel.org/g/878tz22peb.fsf@gmail.com drivers/staging/android/sync_debug.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/staging/android/sync_debug.c b/drivers/staging/android/sync_debug.c index 5f57499..1197f9e 100644 --- a/drivers/staging/android/sync_debug.c +++ b/drivers/staging/android/sync_debug.c @@ -326,9 +326,15 @@ static __init int sync_debugfs_init(void) { dbgfs = debugfs_create_dir("sync", NULL); - debugfs_create_file("info", 0444, dbgfs, NULL, &sync_info_debugfs_fops); - debugfs_create_file("sw_sync", 0644, dbgfs, NULL, - &sw_sync_debugfs_fops); + /* + * The debugfs files won't ever get removed and thus, there is + * no need to protect it against removal races. The use of + * debugfs_create_file_unsafe() is actually safe here. + */ + debugfs_create_file_unsafe("info", 0444, dbgfs, NULL, + &sync_info_debugfs_fops); + debugfs_create_file_unsafe("sw_sync", 0644, dbgfs, NULL, + &sw_sync_debugfs_fops); return 0; } -- 2.8.2