From: Oleg Nesterov <oleg@redhat.com>
To: Namhyung Kim <namhyung@gmail.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.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
Subject: Re: probe_event_disable()->synchronize_sched()
Date: Thu, 3 Jul 2014 17:41:31 +0200 [thread overview]
Message-ID: <20140703154131.GA5610@redhat.com> (raw)
In-Reply-To: <87pphn45y6.fsf@sejong.aot.lge.com>
On 07/03, Namhyung Kim wrote:
>
> On Tue, 1 Jul 2014 21:31:47 +0200, Oleg Nesterov wrote:
> >
> > And. I am puzzled by probe_event_disable()->synchronize_sched(). Why
> > do we need it? I mean, why we can't use call_rcu() ? The comment says
> > "synchronize with u{,ret}probe_trace_func" but it doesn't explain _why_
> > do we need to sync.
>
> It looks like the code was copied from trace_kprobe.c file. But IIUC,
> unlike kprobes, uprobe events are always called in a process context.
>
> Also u{,ret}probe_trace_func() call handlers under rcu_read_lock() not
> rcu_read_lock_sched() so I guess the synchronize_sched() can go.
Heh ;) I didn't even notice that "synchronize" and "lock" do not match.
So this should be fixed anyway. But lets discuss other issues first.
Oleg.
next prev parent reply other threads:[~2014-07-03 15:43 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 ` Oleg Nesterov [this message]
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 ` probe_event_disable()->synchronize_sched() Namhyung Kim
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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