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=-5.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI 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 094097DF93 for ; Wed, 4 Jul 2018 09:17:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934382AbeGDJR2 (ORCPT ); Wed, 4 Jul 2018 05:17:28 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:55278 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S934617AbeGDJRF (ORCPT ); Wed, 4 Jul 2018 05:17:05 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w6499Eoe043958 for ; Wed, 4 Jul 2018 05:17:04 -0400 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0b-001b2d01.pphosted.com with ESMTP id 2k0qae9y66-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 04 Jul 2018 05:17:04 -0400 Received: from localhost by e06smtp01.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 4 Jul 2018 10:17:02 +0100 Received: from b06cxnps4074.portsmouth.uk.ibm.com (9.149.109.196) by e06smtp01.uk.ibm.com (192.168.101.131) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 4 Jul 2018 10:16:57 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w649Guwv36176018 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 4 Jul 2018 09:16:56 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7DF6411C04C; Wed, 4 Jul 2018 12:17:21 +0100 (BST) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 83FC811C054; Wed, 4 Jul 2018 12:17:18 +0100 (BST) Received: from linux.vnet.ibm.com (unknown [9.40.192.68]) by d06av25.portsmouth.uk.ibm.com (Postfix) with SMTP; Wed, 4 Jul 2018 12:17:18 +0100 (BST) Date: Wed, 4 Jul 2018 02:16:52 -0700 From: Srikar Dronamraju To: Ravi Bangoria Cc: Oleg Nesterov , rostedt@goodmis.org, mhiramat@kernel.org, peterz@infradead.org, mingo@redhat.com, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org, linux-kernel@vger.kernel.org, corbet@lwn.net, linux-doc@vger.kernel.org, ananth@linux.vnet.ibm.com, alexis.berlemont@gmail.com, naveen.n.rao@linux.vnet.ibm.com, linux-arm-kernel@lists.infradead.org, linux-mips@linux-mips.org, linux@armlinux.org.uk, ralf@linux-mips.org, paul.burton@mips.com Subject: Re: [PATCH v5 06/10] Uprobes: Support SDT markers having reference count (semaphore) Reply-To: Srikar Dronamraju References: <20180628052209.13056-1-ravi.bangoria@linux.ibm.com> <20180628052209.13056-7-ravi.bangoria@linux.ibm.com> <20180701210935.GA14404@redhat.com> <0c543791-f3b7-5a4b-f002-e1c76bb430c0@linux.ibm.com> <20180702180156.GA31400@redhat.com> <20180703061612.GG65296@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-TM-AS-GCONF: 00 x-cbid: 18070409-4275-0000-0000-0000029504A0 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18070409-4276-0000-0000-0000379C87A5 Message-Id: <20180704091652.GA21902@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-07-04_03:,, 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 mlxscore=0 impostorscore=0 mlxlogscore=952 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1806210000 definitions=main-1807040109 Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org > > I'm not sure if I get your concerns but let me try to explain what happens > in such cases. please let me know if I misunderstood your point. > > 1. Install a probe using perf. > # ./perf probe sdt_tick:loop2 > > > > Does this explain your concerns? > No, this was not my concern. My concern is with two users on the same USDT. 1. First user enables the probe point but doesn't increment the ref_cnt. via uprobe_register 2. Second user tries to enable the probe point and also increments the ref_cnt via uprobe_register_refctr. 3. If the second user now removes the probe point via uprobe_unregister. 4. What is the state of the ref_cnt? -- Thanks and Regards Srikar -- 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