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=unavailable 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 726F77D072 for ; Thu, 28 Jun 2018 05:23:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933130AbeF1FXG (ORCPT ); Thu, 28 Jun 2018 01:23:06 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:58756 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932930AbeF1FXE (ORCPT ); Thu, 28 Jun 2018 01:23:04 -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 w5S5J8Ue144854 for ; Thu, 28 Jun 2018 01:23:04 -0400 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2jvs5gryym-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 28 Jun 2018 01:23:04 -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) Thu, 28 Jun 2018 06:22:56 +0100 Received: from d06av24.portsmouth.uk.ibm.com (d06av24.portsmouth.uk.ibm.com [9.149.105.60]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w5S5Mttm27328746 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 28 Jun 2018 05:22:55 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0AFA942042; Thu, 28 Jun 2018 06:22:46 +0100 (BST) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BA37A42049; Thu, 28 Jun 2018 06:22:42 +0100 (BST) Received: from bangoria.in.ibm.com (unknown [9.124.31.233]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 28 Jun 2018 06:22:42 +0100 (BST) From: Ravi Bangoria To: srikar@linux.vnet.ibm.com, oleg@redhat.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, linux-arm-kernel@lists.infradead.org, linux-mips@linux-mips.org, linux@armlinux.org.uk, ralf@linux-mips.org, paul.burton@mips.com, Ravi Bangoria Subject: [PATCH v5 09/10] Uprobes/sdt: Document about reference counter Date: Thu, 28 Jun 2018 10:52:08 +0530 X-Mailer: git-send-email 2.14.4 In-Reply-To: <20180628052209.13056-1-ravi.bangoria@linux.ibm.com> References: <20180628052209.13056-1-ravi.bangoria@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18062805-0008-0000-0000-0000024CAA51 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18062805-0009-0000-0000-000021B3222D Message-Id: <20180628052209.13056-10-ravi.bangoria@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-06-28_02:,, 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=8.0.1-1806210000 definitions=main-1806280059 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 98d3f692957a..0c27c654a21f 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 a0079b4c7a49..a46268e2aa6a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4609,7 +4609,7 @@ static const char readme_msg[] = "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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