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From: Namhyung Kim <namhyung@kernel.org>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Oleg Nesterov <oleg@redhat.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	Tom Zanussi <tom.zanussi@linux.intel.com>,
	"zhangwei\(Jovi\)" <jovi.zhangwei@huawei.com>,
	linux-kernel@vger.kernel.org,
	"yrl.pp-manager.tt\@hitachi.com" <yrl.pp-manager.tt@hitachi.com>
Subject: Re: probe_event_disable()->synchronize_sched()
Date: Fri, 04 Jul 2014 17:01:47 +0900	[thread overview]
Message-ID: <87d2dl4kno.fsf@sejong.aot.lge.com> (raw)
In-Reply-To: <53B5FCC3.8010303@hitachi.com> (Masami Hiramatsu's message of "Fri, 04 Jul 2014 10:00:51 +0900")

Hi Masami,

On Fri, 04 Jul 2014 10:00:51 +0900, Masami Hiramatsu wrote:
> (2014/07/03 16:44), Namhyung Kim wrote:
>> Hi Masami,
>> 
>> On Thu, 03 Jul 2014 14:46:09 +0900, Masami Hiramatsu wrote:
>>> One possible scenario is here; someone disables an event and tries to remove
>>> it (both will be done by different syscalls). If we don't synchronize
>>> the first disabling, the event flag set disabled, but the event itself
>>> is not disabled. Thus event handler is still possible to be running
>>> somewhere when it is removed.
>> 
>> But, IIUC both of disable and remove path are protected by event_mutex.
>> So one cannot see the case of disabled event flag but enabled event, no?
>
> No, the flag is not protect the trace event handler itself.
> I meant that running handlers and the flag was not synchronized.

Ah, right.  Thanks for explanation. :)

Thanks,
Namhyung

  reply	other threads:[~2014-07-04  8:02 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-27 17:01 [PATCH 0/4] tracing/uprobes fixes Oleg Nesterov
2014-06-27 17:01 ` [PATCH 1/4] tracing/uprobes: Revert "Support mix of ftrace and perf" Oleg Nesterov
2014-06-30  5:49   ` Namhyung Kim
2014-06-30 18:48     ` Oleg Nesterov
2014-07-01 19:31       ` probe_event_disable()->synchronize_sched() (Was: tracing/uprobes: Revert "Support mix of ftrace and perf") Oleg Nesterov
2014-07-03  0:54         ` probe_event_disable()->synchronize_sched() Namhyung Kim
2014-07-03 15:41           ` probe_event_disable()->synchronize_sched() Oleg Nesterov
2014-07-03  5:35         ` probe_event_disable()->synchronize_sched() (Was: tracing/uprobes: Revert "Support mix of ftrace and perf") Masami Hiramatsu
2014-07-03  5:46         ` Masami Hiramatsu
2014-07-03  7:44           ` probe_event_disable()->synchronize_sched() Namhyung Kim
2014-07-04  1:00             ` probe_event_disable()->synchronize_sched() Masami Hiramatsu
2014-07-04  8:01               ` Namhyung Kim [this message]
2014-07-03 16:22           ` probe_event_disable()->synchronize_sched() (Was: tracing/uprobes: Revert "Support mix of ftrace and perf") Oleg Nesterov
2014-07-03 17:01             ` __trace_remove_event_dirs() leaks file->filter ? (Was: probe_event_disable()->synchronize_sched()) Oleg Nesterov
2014-07-04  5:21               ` Masami Hiramatsu
2014-07-04 19:38                 ` Oleg Nesterov
2014-07-04  4:46             ` probe_event_disable()->synchronize_sched() (Was: tracing/uprobes: Revert "Support mix of ftrace and perf") Masami Hiramatsu
2014-06-30 11:52   ` [PATCH 1/4] tracing/uprobes: Revert "Support mix of ftrace and perf" Masami Hiramatsu
2014-06-30 16:56   ` Srikar Dronamraju
2014-06-27 17:01 ` [PATCH 2/4] uprobes: Change unregister/apply to WARN() if uprobe/consumer is gone Oleg Nesterov
2014-06-30  5:50   ` Namhyung Kim
2014-06-30 16:57   ` Srikar Dronamraju
2014-06-27 17:01 ` [PATCH 3/4] tracing/uprobes: Kill the bogus UPROBE_HANDLER_REMOVE code in uprobe_dispatcher() Oleg Nesterov
2014-06-30  6:03   ` Namhyung Kim
2014-06-30 16:57   ` Srikar Dronamraju
2014-06-27 17:01 ` [PATCH 4/4] tracing/uprobes: Fix the usage of uprobe_buffer_enable() in probe_event_enable() Oleg Nesterov
2014-06-30  6:18   ` Namhyung Kim
2014-06-30 11:49   ` Masami Hiramatsu
2014-06-30 17:04   ` Srikar Dronamraju
2014-06-30 17:21     ` Steven Rostedt
2014-06-30 17:58       ` Oleg Nesterov
2014-06-30 18:22         ` Steven Rostedt
2014-06-30 17:50     ` Oleg Nesterov
2014-06-30 18:01       ` Steven Rostedt
2014-06-30 13:28 ` [PATCH 0/4] tracing/uprobes fixes Steven Rostedt

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