From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4509AC00523 for ; Fri, 3 Jan 2020 08:51:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1778E21734 for ; Fri, 3 Jan 2020 08:51:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="kPalE5uc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727227AbgACIvE (ORCPT ); Fri, 3 Jan 2020 03:51:04 -0500 Received: from userp2130.oracle.com ([156.151.31.86]:32788 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725972AbgACIvE (ORCPT ); Fri, 3 Jan 2020 03:51:04 -0500 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 0038ht9v138539; Fri, 3 Jan 2020 08:50:14 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2019-08-05; bh=tzuXPE/Pks4hujfIYPzNgVGPbsKo4j/Ts3ZzA5B7ZZs=; b=kPalE5ucdFXLKZ/tpsrqgDQDYHOLQNdrC6ttTw+laxN2MOpmdp4wtGW3AnGnk4uQLHnS Z4t4Jzo/SvFmpkxNqE7gf1c8FRLwxYshO8Gw8uHdTg3kLX+7t/aRUoIWx2al3k33H2K9 heO5i/qeEz+fyZzF2WMmxCx1yfHZGBLpMQ4t7sHWVjk+8BjJjaCwx3JRYSLl68unTgDv 59BCqr+Lb6ddVOzjF4KwmU6LZAbYjGn9l5FnIwbvRvxbbJQVF9Bxo5MwNt/bvMBkBoUJ 7NCDgRZ4sZfkP9PvagVyCutXdZj1+vSn61f/8NmtQo0YpEBdPxRTCDSLrUomkSouLKAH cA== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by userp2130.oracle.com with ESMTP id 2x5xftucc4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 03 Jan 2020 08:50:13 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 0038nF2L105835; Fri, 3 Jan 2020 08:50:13 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3020.oracle.com with ESMTP id 2x8guw81xv-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 03 Jan 2020 08:50:12 +0000 Received: from abhmp0002.oracle.com (abhmp0002.oracle.com [141.146.116.8]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 0038o94j018279; Fri, 3 Jan 2020 08:50:09 GMT Received: from kadam (/129.205.23.165) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 03 Jan 2020 00:50:08 -0800 Date: Fri, 3 Jan 2020 11:49:59 +0300 From: Dan Carpenter To: Aditya Pakki Cc: Greg Kroah-Hartman , devel@driverdev.osuosl.org, Harsh Jain , Vandana BN , kjlu@umn.edu, linux-kernel@vger.kernel.org, Simon =?iso-8859-1?Q?Sandstr=F6m?= Subject: Re: [PATCH] staging: kpc2000: replace assertion with recovery code Message-ID: <20200103084959.GA3911@kadam> References: <20191215181243.31519-1-pakki001@umn.edu> <20191215182814.GA859066@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191215182814.GA859066@kroah.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9488 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001030083 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9488 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001030083 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Dec 15, 2019 at 07:28:14PM +0100, Greg Kroah-Hartman wrote: > On Sun, Dec 15, 2019 at 12:12:37PM -0600, Aditya Pakki wrote: > > In kpc_dma_transfer, if either priv or ldev is NULL, crashing the > > process is excessive and is not needed. Instead of asserting, by > > passing the error upstream, the error can be handled. > > > > Signed-off-by: Aditya Pakki > > --- > > drivers/staging/kpc2000/kpc_dma/fileops.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c > > index cb52bd9a6d2f..1c4633267cc1 100644 > > --- a/drivers/staging/kpc2000/kpc_dma/fileops.c > > +++ b/drivers/staging/kpc2000/kpc_dma/fileops.c > > @@ -49,9 +49,11 @@ static int kpc_dma_transfer(struct dev_private_data *priv, > > u64 dma_addr; > > u64 user_ctl; > > > > - BUG_ON(priv == NULL); > > + if (!priv) > > + return -EINVAL; > > How can prive ever be NULL here? Can you track back to all callers to > verify this? If so, just remove the check. > Smatch says that "priv" can't be NULL. Also if you have a NULL dereference the kernel prints a nice stack trace. Normally just doing the NULL dereference and Oopsing is better than doing a BUG_ON(). The one exception would be when the Oops leads to filesystem corruption. regards, dan carpenter