From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751755AbaJSAc6 (ORCPT ); Sat, 18 Oct 2014 20:32:58 -0400 Received: from mx02b.posteo.de ([89.146.230.120]:57988 "EHLO mx02.posteo.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751589AbaJSAcz (ORCPT ); Sat, 18 Oct 2014 20:32:55 -0400 From: Martin Kepplinger To: gregkh@linuxfoundation.org Cc: arnd@arndb.de, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Martin Kepplinger Subject: [PATCH 1/3] misc: always assign miscdevice to file->private_data in open() Date: Sun, 19 Oct 2014 02:30:58 +0200 Message-Id: <1413678660-29669-1-git-send-email-martink@posteo.de> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <5442F3D0.3070203@posteo.de> References: <5442F3D0.3070203@posteo.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As of now, a miscdevice driver has to provide an implementation of the open() file operation if it wants to have misc_open() assign a pointer to struct miscdevice to file->private_data for other file operations to use (given the user calls open()). This leads to situations where a miscdevice driver that doesn't need internal operations during open() has to implement open() that only returns immediately, in order to use the data in private_data in other fops. This provides consistent behaviour for miscdevice developers and will always provide the pointer in private_data. A driver's open() fop would, of course, just overwrite it, when using private_data itself. Signed-off-by: Martin Kepplinger --- The mentioned warning is appearently unrelated here, and happens on mainline v3.17 awell -.- sorry for the confusion. This applies to 3.17 and is a call for review and opinions. Especially on the followup patches. drivers/char/misc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/char/misc.c b/drivers/char/misc.c index ffa97d2..205ad4c 100644 --- a/drivers/char/misc.c +++ b/drivers/char/misc.c @@ -142,8 +142,8 @@ static int misc_open(struct inode * inode, struct file * file) err = 0; replace_fops(file, new_fops); + file->private_data = c; if (file->f_op->open) { - file->private_data = c; err = file->f_op->open(inode,file); } fail: -- 1.7.10.4