From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-4.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_HI,T_RP_MATCHES_RCVD autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 2B6E47E66E for ; Fri, 16 Mar 2018 09:28:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750793AbeCPJ24 (ORCPT ); Fri, 16 Mar 2018 05:28:56 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:33322 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751022AbeCPJ2z (ORCPT ); Fri, 16 Mar 2018 05:28:55 -0400 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w2G9R6qZ121271 for ; Fri, 16 Mar 2018 05:28:55 -0400 Received: from e06smtp15.uk.ibm.com (e06smtp15.uk.ibm.com [195.75.94.111]) by mx0a-001b2d01.pphosted.com with ESMTP id 2gr924wc3v-1 (version=TLSv1.2 cipher=AES256-SHA256 bits=256 verify=NOT) for ; Fri, 16 Mar 2018 05:28:54 -0400 Received: from localhost by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Fri, 16 Mar 2018 09:28:48 -0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w2G9Smji32178288; Fri, 16 Mar 2018 09:28:48 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E8062A4040; Fri, 16 Mar 2018 09:21:35 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 099BDA405D; Fri, 16 Mar 2018 09:21:27 +0000 (GMT) Received: from [9.79.219.128] (unknown [9.79.219.128]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 16 Mar 2018 09:21:26 +0000 (GMT) Subject: Re: [PATCH 5/8] trace_uprobe: Support SDT markers having reference count (semaphore) To: Oleg Nesterov Cc: mhiramat@kernel.org, peterz@infradead.org, srikar@linux.vnet.ibm.com, acme@kernel.org, ananth@linux.vnet.ibm.com, akpm@linux-foundation.org, alexander.shishkin@linux.intel.com, alexis.berlemont@gmail.com, corbet@lwn.net, dan.j.williams@intel.com, gregkh@linuxfoundation.org, huawei.libin@huawei.com, hughd@google.com, jack@suse.cz, jglisse@redhat.com, jolsa@redhat.com, kan.liang@intel.com, kirill.shutemov@linux.intel.com, kjlx@templeofstupid.com, kstewart@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, milian.wolff@kdab.com, mingo@redhat.com, namhyung@kernel.org, naveen.n.rao@linux.vnet.ibm.com, pc@us.ibm.com, pombredanne@nexb.com, rostedt@goodmis.org, tglx@linutronix.de, tmricht@linux.vnet.ibm.com, willy@infradead.org, yao.jin@linux.intel.com, fengguang.wu@intel.com, Ravi Bangoria References: <20180313125603.19819-1-ravi.bangoria@linux.vnet.ibm.com> <20180313125603.19819-6-ravi.bangoria@linux.vnet.ibm.com> <20180315150156.GA19767@redhat.com> From: Ravi Bangoria Date: Fri, 16 Mar 2018 15:01:05 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180315150156.GA19767@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 18031609-0020-0000-0000-00000405DDE2 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18031609-0021-0000-0000-00004299E987 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-03-16_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1803160115 Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 03/15/2018 08:31 PM, Oleg Nesterov wrote: > On 03/13, Ravi Bangoria wrote: >> +sdt_update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d) >> +{ >> + void *kaddr; >> + struct page *page; >> + struct vm_area_struct *vma; >> + int ret = 0; >> + unsigned short orig = 0; >> + >> + if (vaddr == 0) >> + return -EINVAL; >> + >> + ret = get_user_pages_remote(NULL, mm, vaddr, 1, >> + FOLL_FORCE | FOLL_WRITE, &page, &vma, NULL); >> + if (ret <= 0) >> + return ret; >> + >> + kaddr = kmap_atomic(page); >> + memcpy(&orig, kaddr + (vaddr & ~PAGE_MASK), sizeof(orig)); >> + orig += d; >> + memcpy(kaddr + (vaddr & ~PAGE_MASK), &orig, sizeof(orig)); >> + kunmap_atomic(kaddr); > Hmm. Why memcpy? You could simply do > > kaddr = kmap_atomic(); > unsigned short *ptr = kaddr + (vaddr & ~PAGE_MASK); > *ptr += d; > kunmap_atomic(); Yes, that should work. Will change it. Thanks for the review, Ravi -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html