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 395BC7DF90 for ; Wed, 20 Jun 2018 03:57:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754653AbeFTD5i (ORCPT ); Tue, 19 Jun 2018 23:57:38 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:48344 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754637AbeFTD5P (ORCPT ); Tue, 19 Jun 2018 23:57:15 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w5K3t7rs059207 for ; Tue, 19 Jun 2018 23:57:15 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2jqeeghvxa-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 19 Jun 2018 23:57:14 -0400 Received: from localhost by e06smtp02.uk.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) Wed, 20 Jun 2018 04:57:07 +0100 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w5K3v6lt31981800 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 20 Jun 2018 03:57:06 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D805FAE053; Wed, 20 Jun 2018 04:45:48 +0100 (BST) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 27928AE055; Wed, 20 Jun 2018 04:45:46 +0100 (BST) Received: from bangoria.in.ibm.com (unknown [9.124.31.59]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 20 Jun 2018 04:45:45 +0100 (BST) From: Ravi Bangoria To: oleg@redhat.com, srikar@linux.vnet.ibm.com, rostedt@goodmis.org, mhiramat@kernel.org Cc: 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, Ravi Bangoria Subject: [PATCH v4 8/9] Uprobes/sdt: Document about reference counter Date: Wed, 20 Jun 2018 09:26:28 +0530 X-Mailer: git-send-email 2.14.4 In-Reply-To: <20180620035629.7844-1-ravi.bangoria@linux.ibm.com> References: <20180620035629.7844-1-ravi.bangoria@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18062003-0008-0000-0000-00000249A67A X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18062003-0009-0000-0000-000021AFF540 Message-Id: <20180620035629.7844-9-ravi.bangoria@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-06-20_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=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1805220000 definitions=main-1806200044 Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Reference counter gate the invocation of probe. If present, by default reference count is 0. Kernel needs to increment it before tracing the probe and decrement it when done. This is identical to semaphore in Userspace Statically Defined Tracepoints (USDT). Document usage of reference counter. Signed-off-by: Ravi Bangoria Acked-by: Masami Hiramatsu --- Documentation/trace/uprobetracer.rst | 16 +++++++++++++--- kernel/trace/trace.c | 2 +- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/Documentation/trace/uprobetracer.rst b/Documentation/trace/uprobetracer.rst index 98d3f69..0c27c65 100644 --- a/Documentation/trace/uprobetracer.rst +++ b/Documentation/trace/uprobetracer.rst @@ -22,15 +22,25 @@ Synopsis of uprobe_tracer ------------------------- :: - p[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS] : Set a uprobe - r[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS] : Set a return uprobe (uretprobe) - -:[GRP/]EVENT : Clear uprobe or uretprobe event + p[:[GRP/]EVENT] PATH:OFFSET[(REF_CTR_OFFSET)] [FETCHARGS] + r[:[GRP/]EVENT] PATH:OFFSET[(REF_CTR_OFFSET)] [FETCHARGS] + -:[GRP/]EVENT + + p : Set a uprobe + r : Set a return uprobe (uretprobe) + - : Clear uprobe or uretprobe event GRP : Group name. If omitted, "uprobes" is the default value. EVENT : Event name. If omitted, the event name is generated based on PATH+OFFSET. PATH : Path to an executable or a library. OFFSET : Offset where the probe is inserted. + REF_CTR_OFFSET: Reference counter offset. Optional field. Reference count + gate the invocation of probe. If present, by default + reference count is 0. Kernel needs to increment it before + tracing the probe and decrement it when done. This is + identical to semaphore in Userspace Statically Defined + Tracepoints (USDT). FETCHARGS : Arguments. Each probe can have up to 128 args. %REG : Fetch register REG diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index c9336e9..08f3e75 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4613,7 +4613,7 @@ static int tracing_trace_options_open(struct inode *inode, struct file *file) "place (kretprobe): [:][+]|\n" #endif #ifdef CONFIG_UPROBE_EVENTS - "\t place: :\n" + " place (uprobe): :[(ref_ctr_offset)]\n" #endif "\t args: =fetcharg[:type]\n" "\t fetcharg: %, @
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