From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH 01/18] drivers core: Add I/O ASID allocator Date: Tue, 9 Apr 2019 07:53:08 -0700 Message-ID: <20190409145308.GZ14111@linux.ibm.com> References: <1554767973-30125-1-git-send-email-jacob.jun.pan@linux.intel.com> <1554767973-30125-2-git-send-email-jacob.jun.pan@linux.intel.com> <20190409100049.GC9224@smile.fi.intel.com> <20190409100436.GA28683@infradead.org> <20190409103030.GK9224@smile.fi.intel.com> Reply-To: paulmck@linux.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190409103030.GK9224@smile.fi.intel.com> Sender: linux-kernel-owner@vger.kernel.org To: Andriy Shevchenko Cc: Christoph Hellwig , Jacob Pan , iommu@lists.linux-foundation.org, LKML , Joerg Roedel , David Woodhouse , Alex Williamson , Jean-Philippe Brucker , Yi Liu , "Tian, Kevin" , Raj Ashok , Lu Baolu List-Id: iommu@lists.linux-foundation.org On Tue, Apr 09, 2019 at 01:30:30PM +0300, Andriy Shevchenko wrote: > On Tue, Apr 09, 2019 at 03:04:36AM -0700, Christoph Hellwig wrote: > > On Tue, Apr 09, 2019 at 01:00:49PM +0300, Andriy Shevchenko wrote: > > > I think it makes sense to add a helper macro to rcupdate.h > > > (and we have several cases in kernel that can utilize it) > > > > > > #define kfree_non_null_rcu(ptr, rcu_head) \ > > > do { \ > > > if (ptr) \ > > > kfree_rcu(ptr, rcu_head); \ > > > } while (0) > > > > > > as a more common pattern for resource deallocators. > > > > I think that should move straight into kfree_rcu. > > Possible. I didn't dare to offer this due to lack of knowledge how it's used in > other places. > > > In general > > we expect *free* to deal with NULL pointers transparently, so we > > should do so here as well. > > Exactly my point, thanks. As shown below? And now that you mention it, it is a bit surprising that no one has complained before. ;-) Thanx, Paul ------------------------------------------------------------------------ commit 23ad938244968e9d2a8001a1c52887c113b182f6 Author: Paul E. McKenney Date: Tue Apr 9 07:48:18 2019 -0700 rcu: Make kfree_rcu() ignore NULL pointers This commit makes the kfree_rcu() macro's semantics be consistent with the likes of kfree() by adding a check for NULL pointers, so that kfree_rcu(NULL, ...) is a no-op. Reported-by: Andriy Shevchenko Reported-by: Christoph Hellwig Signed-off-by: Paul E. McKenney diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 922bb6848813..c68649b9bcec 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -828,9 +828,13 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) * The BUILD_BUG_ON check must not involve any function calls, hence the * checks are done in macros here. */ -#define kfree_rcu(ptr, rcu_head) \ - __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head)) - +#define kfree_rcu(ptr, rhf) \ +do { \ + typeof (ptr) ___p = (ptr); \ + \ + if (___p) \ + __kfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \ +} while (0) /* * Place this after a lock-acquisition primitive to guarantee that 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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=unavailable 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 B120AC10F0E for ; Tue, 9 Apr 2019 16:03:27 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 7D3A52084C for ; Tue, 9 Apr 2019 16:03:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7D3A52084C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 3FA5AFF6; Tue, 9 Apr 2019 16:03:27 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id CDEA6B8A for ; Tue, 9 Apr 2019 15:55:41 +0000 (UTC) X-Greylist: delayed 01:02:26 by SQLgrey-1.7.6 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 23CBD76D for ; Tue, 9 Apr 2019 15:55:41 +0000 (UTC) Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x39EeUQw073041 for ; Tue, 9 Apr 2019 10:53:14 -0400 Received: from e14.ny.us.ibm.com (e14.ny.us.ibm.com [129.33.205.204]) by mx0a-001b2d01.pphosted.com with ESMTP id 2rru3eqp2u-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 09 Apr 2019 10:53:14 -0400 Received: from localhost by e14.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 9 Apr 2019 15:53:09 +0100 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x39Er8Jn27787270 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 9 Apr 2019 14:53:08 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2C382B2067; Tue, 9 Apr 2019 14:53:08 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0D4CBB2068; Tue, 9 Apr 2019 14:53:08 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.70.82.188]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 9 Apr 2019 14:53:07 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id 04B7016C34AA; Tue, 9 Apr 2019 07:53:08 -0700 (PDT) Date: Tue, 9 Apr 2019 07:53:08 -0700 From: "Paul E. McKenney" To: Andriy Shevchenko Subject: Re: [PATCH 01/18] drivers core: Add I/O ASID allocator References: <1554767973-30125-1-git-send-email-jacob.jun.pan@linux.intel.com> <1554767973-30125-2-git-send-email-jacob.jun.pan@linux.intel.com> <20190409100049.GC9224@smile.fi.intel.com> <20190409100436.GA28683@infradead.org> <20190409103030.GK9224@smile.fi.intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190409103030.GK9224@smile.fi.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 19040914-0052-0000-0000-000003A99DE3 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010896; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000284; SDB=6.01186624; UDB=6.00621496; IPR=6.00967384; MB=3.00026363; MTD=3.00000008; XFM=3.00000015; UTC=2019-04-09 14:53:12 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19040914-0053-0000-0000-0000606FB512 Message-Id: <20190409145308.GZ14111@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-04-09_06:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 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=8.0.1-1810050000 definitions=main-1904090094 X-Mailman-Approved-At: Tue, 09 Apr 2019 16:03:26 +0000 Cc: "Tian, Kevin" , Alex Williamson , Raj Ashok , Jean-Philippe Brucker , LKML , iommu@lists.linux-foundation.org, David Woodhouse X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: paulmck@linux.ibm.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org Message-ID: <20190409145308.WcMD9-O8UPWhQ9SpXAfSCP1vDGmq27BmbDndSVhXi3U@z> On Tue, Apr 09, 2019 at 01:30:30PM +0300, Andriy Shevchenko wrote: > On Tue, Apr 09, 2019 at 03:04:36AM -0700, Christoph Hellwig wrote: > > On Tue, Apr 09, 2019 at 01:00:49PM +0300, Andriy Shevchenko wrote: > > > I think it makes sense to add a helper macro to rcupdate.h > > > (and we have several cases in kernel that can utilize it) > > > > > > #define kfree_non_null_rcu(ptr, rcu_head) \ > > > do { \ > > > if (ptr) \ > > > kfree_rcu(ptr, rcu_head); \ > > > } while (0) > > > > > > as a more common pattern for resource deallocators. > > > > I think that should move straight into kfree_rcu. > > Possible. I didn't dare to offer this due to lack of knowledge how it's used in > other places. > > > In general > > we expect *free* to deal with NULL pointers transparently, so we > > should do so here as well. > > Exactly my point, thanks. As shown below? And now that you mention it, it is a bit surprising that no one has complained before. ;-) Thanx, Paul ------------------------------------------------------------------------ commit 23ad938244968e9d2a8001a1c52887c113b182f6 Author: Paul E. McKenney Date: Tue Apr 9 07:48:18 2019 -0700 rcu: Make kfree_rcu() ignore NULL pointers This commit makes the kfree_rcu() macro's semantics be consistent with the likes of kfree() by adding a check for NULL pointers, so that kfree_rcu(NULL, ...) is a no-op. Reported-by: Andriy Shevchenko Reported-by: Christoph Hellwig Signed-off-by: Paul E. McKenney diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 922bb6848813..c68649b9bcec 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -828,9 +828,13 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) * The BUILD_BUG_ON check must not involve any function calls, hence the * checks are done in macros here. */ -#define kfree_rcu(ptr, rcu_head) \ - __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head)) - +#define kfree_rcu(ptr, rhf) \ +do { \ + typeof (ptr) ___p = (ptr); \ + \ + if (___p) \ + __kfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \ +} while (0) /* * Place this after a lock-acquisition primitive to guarantee that _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu