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=-5.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED,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 C0CD8C433E0 for ; Sat, 27 Jun 2020 13:09:33 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9335421556 for ; Sat, 27 Jun 2020 13:09:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="Ql8e9lUt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9335421556 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 638CC86B18; Sat, 27 Jun 2020 13:09:33 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id EwsHJaZ0yg1p; Sat, 27 Jun 2020 13:09:32 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by whitealder.osuosl.org (Postfix) with ESMTP id 64907869D7; Sat, 27 Jun 2020 13:09:32 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 53815C0863; Sat, 27 Jun 2020 13:09:32 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 00648C016F for ; Sat, 27 Jun 2020 13:09:30 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id E9B5686C2E for ; Sat, 27 Jun 2020 13:09:30 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id b_11n1opWn_b for ; Sat, 27 Jun 2020 13:09:30 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from userp2120.oracle.com (userp2120.oracle.com [156.151.31.85]) by fraxinus.osuosl.org (Postfix) with ESMTPS id 3490685FFD for ; Sat, 27 Jun 2020 13:09:30 +0000 (UTC) Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 05RCwW3Q157642; Sat, 27 Jun 2020 13:09:25 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-2020-01-29; bh=y6Z3ndKwcdvb/o527oos0Vmmml29kOeFL0WHa87IivU=; b=Ql8e9lUtJMlfraXeMxmr7CbqCK9xuMbtf7EWIRx61zzfGC2opBP3kGLATC2sx1f0RDA2 d0Lvy+oGkcU29Lff/OVWhty22/vB9iokcaJ6FClpQ297FuDtl5L2ayJQDzxF7ZNUJmmv E0efY9Sop8sMj7xOUd25EAaXgcWhXaz9lpxi4auYpPgM6aHGFBgG/WaPE1HNt+Bf+UoY 5LFHxswr0Nv7qmXarlD7O7Bocr93+xlVe3um0N5oefhuS5x2pIEkyzqdCUFhcMDumXn1 hrpafsd3CKEf2aQ9rCHTQgUpIIQRcKEDTyGq285awLJVP5wytvkyghJUfa8F/Boo0Oup Ow== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by userp2120.oracle.com with ESMTP id 31wxrmru6e-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Sat, 27 Jun 2020 13:09:25 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 05RCvZxY049144; Sat, 27 Jun 2020 13:09:25 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userp3030.oracle.com with ESMTP id 31wu7s3k7j-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 27 Jun 2020 13:09:25 +0000 Received: from abhmp0013.oracle.com (abhmp0013.oracle.com [141.146.116.19]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 05RD9Mij009209; Sat, 27 Jun 2020 13:09:22 GMT Received: from kadam (/41.57.98.10) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sat, 27 Jun 2020 13:09:21 +0000 Date: Sat, 27 Jun 2020 16:09:15 +0300 From: Dan Carpenter To: Richard Weinberger Subject: Re: Passing NULL dev to dma_alloc_coherent() allowed or not? Message-ID: <20200627130915.GF2571@kadam> References: <1669515915.65540.1593258316061.JavaMail.zimbra@nod.at> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1669515915.65540.1593258316061.JavaMail.zimbra@nod.at> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9664 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 bulkscore=0 spamscore=0 malwarescore=0 adultscore=0 mlxscore=0 suspectscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006270095 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9664 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 mlxlogscore=999 priorityscore=1501 impostorscore=0 bulkscore=0 clxscore=1011 malwarescore=0 phishscore=0 adultscore=0 cotscore=-2147483648 lowpriorityscore=0 suspectscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006270095 Cc: linux-kernel@vger.kernel.org, sumit.semwal@linaro.org, iommu@lists.linux-foundation.org, robin.murphy@arm.com, hch@lst.de X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Sat, Jun 27, 2020 at 01:45:16PM +0200, Richard Weinberger wrote: > Hi! > > While porting on an old out-of-tree driver I noticed that dma_alloc_coherent() > was used with dev being NULL. > > commit 148a97d5a02a62f81b5d6176f871c94a65e1f3af > Author: Dan Carpenter > Date: Wed Apr 24 17:24:37 2019 +0300 > > dma-mapping: remove an unnecessary NULL check > > We already dereferenced "dev" when we called get_dma_ops() so this NULL > check is too late. We're not supposed to pass NULL "dev" pointers to > dma_alloc_attrs(). > > Signed-off-by: Dan Carpenter > Signed-off-by: Christoph Hellwig > > says that dma_alloc_attrs() with dev being NULL is not allowed, but in > include/linux/dma-mapping.h we have: > > static inline void *dma_alloc_coherent(struct device *dev, size_t size, > dma_addr_t *dma_handle, gfp_t gfp) > { > > return dma_alloc_attrs(dev, size, dma_handle, gfp, > (gfp & __GFP_NOWARN) ? DMA_ATTR_NO_WARN : 0); > } > > In Linus' tree I see at least three callers of dma_alloc_coherent() with a NULL device. > drivers/staging/emxx_udc/emxx_udc.c:2596: ep->virt_buf = dma_alloc_coherent(NULL, PAGE_SIZE, > drivers/tty/synclink.c:3667: info->buffer_list = dma_alloc_coherent(NULL, BUFFERLISTSIZE, &info->buffer_list_dma_addr, GFP_KERNEL); > drivers/tty/synclink.c:3777: BufferList[i].virt_addr = dma_alloc_coherent(NULL, DMABUFFERSIZE, &BufferList[i].dma_addr, GFP_KERNEL); > > I think these callers are wrong. > Can you please clarify? The are wrong. It was slightly worse when I originally sent the patch but we fixed comedi. https://lkml.org/lkml/2019/4/24/668 regards, dan carpenter _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu