From: Oleg Nesterov <oleg@redhat.com>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Hyeoncheol Lee <cheol.lee@lge.com>,
"zhangwei(Jovi)" <jovi.zhangwei@huawei.com>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
Hemant Kumar <hkshaw@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
Namhyung Kim <namhyung.kim@lge.com>
Subject: Re: [PATCH 16/17] uprobes: Allocate ->utask before handler_chain() for tracing handlers
Date: Wed, 11 Dec 2013 19:11:55 +0100 [thread overview]
Message-ID: <20131211181155.GA25144@redhat.com> (raw)
In-Reply-To: <52A7C347.1060402@hitachi.com>
On 12/11, Masami Hiramatsu wrote:
>
> (2013/12/11 0:57), Oleg Nesterov wrote:
> > On 12/10, Masami Hiramatsu wrote:
> >>
> >> and isn't it better to increment
> >> miss-hit counter of the uprobe?
> >
> > What do you mean? This is not miss-hit and ->utask == NULL is quite normal.
>
> But it could skip the handler_chain silently. It could confuse users
> why their probe doesn't hit as expected.
No, we will restart the same (probed) instruction, handle_swbp()
will be called again, get_utask() will be called again.
Not to mention that (in practice) if GFP_KERNEL fails the task is
already killed.
> > For example, on ppc it can be always NULL because ppc likely emulates the
> > probed insn.
>
> Hmm, in that case, should uprobes handlers never be called on ppc with
> this change?
Why? With this change ppc will have ->utask != NULL even if it doesn't
need it at all.
Oleg.
next prev parent reply other threads:[~2013-12-11 18:11 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-09 6:19 [PATCHSET 00/17] tracing/uprobes: Add support for more fetch methods (v8) Namhyung Kim
2013-12-09 6:19 ` [PATCH 01/17] tracing/uprobes: Fix documentation of uprobe registration syntax Namhyung Kim
2013-12-09 6:19 ` [PATCH 02/17] tracing/probes: Fix basic print type functions Namhyung Kim
2013-12-09 6:19 ` [PATCH 03/17] tracing/kprobes: Factor out struct trace_probe Namhyung Kim
2013-12-09 6:19 ` [PATCH 04/17] tracing/uprobes: Convert to " Namhyung Kim
2013-12-09 6:19 ` [PATCH 05/17] tracing/kprobes: Move common functions to trace_probe.h Namhyung Kim
2013-12-09 6:19 ` [PATCH 06/17] tracing/probes: Integrate duplicate set_print_fmt() Namhyung Kim
2013-12-09 6:19 ` [PATCH 07/17] tracing/probes: Move fetch function helpers to trace_probe.h Namhyung Kim
2013-12-09 15:12 ` Masami Hiramatsu
2013-12-09 6:19 ` [PATCH 08/17] tracing/probes: Split [ku]probes_fetch_type_table Namhyung Kim
2013-12-09 15:09 ` Masami Hiramatsu
2013-12-10 1:05 ` Namhyung Kim
2013-12-10 4:41 ` Namhyung Kim
2013-12-10 9:14 ` Masami Hiramatsu
2013-12-09 6:19 ` [PATCH 09/17] tracing/probes: Implement 'stack' fetch method for uprobes Namhyung Kim
2013-12-09 6:19 ` [PATCH 10/17] tracing/probes: Move 'symbol' fetch method to kprobes Namhyung Kim
2013-12-10 10:12 ` Masami Hiramatsu
2013-12-11 1:05 ` Namhyung Kim
2013-12-11 1:26 ` Masami Hiramatsu
2013-12-09 6:19 ` [PATCH 11/17] tracing/probes: Add fetch{,_size} member into deref fetch method Namhyung Kim
2013-12-09 6:20 ` [PATCH 12/17] tracing/probes: Implement 'memory' fetch method for uprobes Namhyung Kim
2013-12-10 11:00 ` Masami Hiramatsu
2013-12-11 1:15 ` Namhyung Kim
2013-12-11 1:27 ` Masami Hiramatsu
2013-12-09 6:20 ` [PATCH 13/17] tracing/uprobes: Pass 'is_return' to traceprobe_parse_probe_arg() Namhyung Kim
2013-12-09 15:11 ` Masami Hiramatsu
2013-12-09 6:20 ` [PATCH 14/17] tracing/uprobes: Fetch args before reserving a ring buffer Namhyung Kim
2013-12-09 6:20 ` [PATCH 15/17] tracing/uprobes: Add support for full argument access methods Namhyung Kim
2013-12-09 6:20 ` [PATCH 16/17] uprobes: Allocate ->utask before handler_chain() for tracing handlers Namhyung Kim
2013-12-10 10:41 ` Masami Hiramatsu
2013-12-10 15:57 ` Oleg Nesterov
2013-12-11 1:30 ` Namhyung Kim
2013-12-11 1:43 ` Masami Hiramatsu
2013-12-11 18:11 ` Oleg Nesterov [this message]
2013-12-12 5:55 ` Masami Hiramatsu
2013-12-12 19:46 ` Oleg Nesterov
2013-12-13 1:57 ` Masami Hiramatsu
2013-12-13 1:58 ` Masami Hiramatsu
2013-12-09 6:20 ` [PATCH 17/17] tracing/uprobes: Add @+file_offset fetch method Namhyung Kim
-- strict thread matches above, loose matches on Subject: below --
2013-12-16 4:31 [PATCHSET 00/17] tracing/uprobes: Add support for more fetch methods (v9) Namhyung Kim
2013-12-16 4:32 ` [PATCH 16/17] uprobes: Allocate ->utask before handler_chain() for tracing handlers Namhyung Kim
2013-11-27 6:19 [PATCHSET 00/17] tracing/uprobes: Add support for more fetch methods (v7) Namhyung Kim
2013-11-27 6:20 ` [PATCH 16/17] uprobes: Allocate ->utask before handler_chain() for tracing handlers Namhyung Kim
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