From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id DCBEF6B000C for ; Thu, 3 May 2018 10:57:27 -0400 (EDT) Received: by mail-pg0-f71.google.com with SMTP id s7-v6so12179022pgp.15 for ; Thu, 03 May 2018 07:57:27 -0700 (PDT) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id q4-v6si13792331plb.251.2018.05.03.07.57.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 03 May 2018 07:57:26 -0700 (PDT) Date: Thu, 3 May 2018 23:57:21 +0900 From: Masami Hiramatsu Subject: Re: [PATCH v3 8/9] trace_uprobe/sdt: Document about reference counter Message-Id: <20180503235721.d1dbc6f5bfdfc97e6200b7de@kernel.org> In-Reply-To: <20180417043244.7501-9-ravi.bangoria@linux.vnet.ibm.com> References: <20180417043244.7501-1-ravi.bangoria@linux.vnet.ibm.com> <20180417043244.7501-9-ravi.bangoria@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Ravi Bangoria Cc: oleg@redhat.com, peterz@infradead.org, srikar@linux.vnet.ibm.com, rostedt@goodmis.org, 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, jolsa@redhat.com, kan.liang@intel.com, kjlx@templeofstupid.com, kstewart@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, milian.wolff@kdab.com, mingo@redhat.com, namhyung@kernel.org, naveen.n.rao@linux.vnet.ibm.com, pc@us.ibm.com, tglx@linutronix.de, yao.jin@linux.intel.com, fengguang.wu@intel.com, jglisse@redhat.com, Ravi Bangoria On Tue, 17 Apr 2018 10:02:43 +0530 Ravi Bangoria wrote: > From: Ravi Bangoria > > 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 Looks good to me. Acked-by: Masami Hiramatsu Thanks! > --- > Documentation/trace/uprobetracer.txt | 16 +++++++++++++--- > kernel/trace/trace.c | 2 +- > 2 files changed, 14 insertions(+), 4 deletions(-) > > diff --git a/Documentation/trace/uprobetracer.txt b/Documentation/trace/uprobetracer.txt > index bf526a7c..cb6751d 100644 > --- a/Documentation/trace/uprobetracer.txt > +++ b/Documentation/trace/uprobetracer.txt > @@ -19,15 +19,25 @@ user to calculate the offset of the probepoint in the object. > > 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 300f4ea..d211937 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -4604,7 +4604,7 @@ 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: %, @
, @[+|-],\n" > -- > 1.8.3.1 > -- Masami Hiramatsu