From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>,
"zhangwei(Jovi)" <jovi.zhangwei@huawei.com>,
Jiri Olsa <jolsa@redhat.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC][PATCH 0/4] tracing/kprobes/uprobes: Fix race between opening probe event files and deleting probe
Date: Thu, 04 Jul 2013 13:00:55 +0900 [thread overview]
Message-ID: <51D4F377.6080002@hitachi.com> (raw)
In-Reply-To: <20130704033347.807661713@goodmis.org>
(2013/07/04 12:33), Steven Rostedt wrote:
> Currently there exists a race with deleting a kprobe or uprobe and
> a user opening the probe event file or using perf events.
>
> The problem stems from not being able to take the probe_lock from the
> unregister code because we may have the event_mutex at the time, and
> the event mutex may be taken with the probe_lock held.
>
> To solve this, the events get a ref count (using the flags field), where
> when an event file is opened, the ftrace_event_call ref count increments.
> Then this is checked under event_mutex and if set, the unregistering
> of the probe will fail.
>
> Here's a test that shows how things break:
>
> # cd /sys/kernel/debug/tracing
> # echo 'p:sigprocmask sigprocmask' > kprobe_events || exit -1
> # enable_probe() {
> sleep 10
> echo 1
> }
> # file=events/kprobes/sigprocmask/enable
> # enable_probe > $file &
> > kprobe_events
>
> The above will corrupt the kprobe system, as the write to the enable
> file will happen after the kprobe was deleted.
>
> Trying to create the probe again fails:
>
> # echo 'p:sigprocmask sigprocmask' > kprobe_events
> # cat kprobe_events
> p:kprobes/sigprocmask sigprocmask
> # ls events/kprobes/
> enable filter
>
> After applying these patches, the "> kprobe_events" fails due to the
> event being busy.
>
> Masami, please review these patches and give your ack.
Thanks Steven!
> Oleg Nesterov (1):
> tracing: trace_remove_event_call() should fail if call/file is in use
>
> Steven Rostedt (Red Hat) (3):
> tracing: Add ref count to ftrace_event_call
> tracing/kprobes: Fail to unregister if probe event files are open
> tracing/uprobes: Fail to unregister if probe event files are open
I just started to look into the series, but the 3/4 and 4/4 seems same...
Which one is good to go?
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
next prev parent reply other threads:[~2013-07-04 4:01 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-04 3:33 [RFC][PATCH 0/4] tracing/kprobes/uprobes: Fix race between opening probe event files and deleting probe Steven Rostedt
2013-07-04 3:33 ` [RFC][PATCH 1/4] tracing: Add ref count to ftrace_event_call Steven Rostedt
2013-07-04 4:22 ` Masami Hiramatsu
2013-07-04 11:55 ` [RFC PATCH] tracing: Atomically get refcounts of event_call and trace_array Masami Hiramatsu
2013-07-04 12:12 ` Masami Hiramatsu
2013-07-04 12:23 ` Steven Rostedt
2013-07-05 0:32 ` Oleg Nesterov
2013-07-05 2:32 ` Masami Hiramatsu
2013-07-09 7:55 ` [RFC PATCH V2] tracing: Check f_dentry before accessing event_file/call in inode->i_private Masami Hiramatsu
2013-07-15 18:16 ` Oleg Nesterov
2013-07-17 2:10 ` Masami Hiramatsu
2013-07-17 14:51 ` Oleg Nesterov
2013-07-18 2:20 ` Masami Hiramatsu
2013-07-18 14:51 ` Oleg Nesterov
2013-07-19 5:21 ` Masami Hiramatsu
2013-07-19 13:33 ` Oleg Nesterov
2013-07-22 9:57 ` Masami Hiramatsu
2013-07-22 17:04 ` Oleg Nesterov
2013-07-23 21:04 ` Oleg Nesterov
2013-07-04 3:33 ` [RFC][PATCH 2/4] tracing: trace_remove_event_call() should fail if call/file is in use Steven Rostedt
2013-07-04 12:48 ` Masami Hiramatsu
2013-07-04 3:33 ` [RFC][PATCH 3/4] tracing/kprobes: Fail to unregister if probe event files are open Steven Rostedt
2013-07-04 12:45 ` Masami Hiramatsu
2013-07-04 18:48 ` Oleg Nesterov
2013-07-05 2:53 ` Masami Hiramatsu
2013-07-05 17:26 ` Oleg Nesterov
2013-07-08 2:36 ` Masami Hiramatsu
2013-07-08 14:25 ` Oleg Nesterov
2013-07-09 8:01 ` [RFC PATCH] tracing/kprobe: Wait for disabling all running kprobe handlers Masami Hiramatsu
2013-07-09 8:07 ` Peter Zijlstra
2013-07-09 8:20 ` Masami Hiramatsu
2013-07-09 8:21 ` Peter Zijlstra
2013-07-09 8:50 ` Masami Hiramatsu
2013-07-09 9:35 ` [RFC PATCH V2] " Masami Hiramatsu
2013-07-15 18:20 ` Oleg Nesterov
2013-07-18 12:07 ` Masami Hiramatsu
2013-07-18 14:35 ` Steven Rostedt
2013-07-30 8:15 ` [RFC][PATCH 3/4] tracing/kprobes: Fail to unregister if probe event files are open Masami Hiramatsu
2013-07-31 19:49 ` Steven Rostedt
2013-07-31 20:40 ` Oleg Nesterov
2013-07-31 22:42 ` Steven Rostedt
2013-08-01 2:07 ` Steven Rostedt
2013-08-01 2:50 ` Steven Rostedt
2013-08-01 3:48 ` Masami Hiramatsu
2013-08-01 13:34 ` Oleg Nesterov
2013-08-01 13:49 ` Oleg Nesterov
2013-08-01 14:17 ` Steven Rostedt
2013-08-01 14:33 ` Oleg Nesterov
2013-08-01 14:45 ` Steven Rostedt
2013-08-01 14:46 ` Oleg Nesterov
2013-08-02 4:57 ` Masami Hiramatsu
2013-08-01 13:10 ` Oleg Nesterov
2013-07-04 3:33 ` [RFC][PATCH 4/4] tracing/uprobes: " Steven Rostedt
2013-08-01 3:40 ` Steven Rostedt
2013-08-01 14:08 ` Oleg Nesterov
2013-08-01 14:25 ` Steven Rostedt
2013-07-04 4:00 ` Masami Hiramatsu [this message]
2013-07-04 6:14 ` Re: [RFC][PATCH 0/4] tracing/kprobes/uprobes: Fix race between opening probe event files and deleting probe Masami Hiramatsu
2013-07-12 13:09 ` Masami Hiramatsu
2013-07-12 17:53 ` Oleg Nesterov
2013-07-15 18:01 ` Oleg Nesterov
2013-07-16 16:38 ` Oleg Nesterov
2013-07-16 19:10 ` Steven Rostedt
2013-07-16 19:22 ` Oleg Nesterov
2013-07-16 19:38 ` Steven Rostedt
2013-07-17 16:03 ` Steven Rostedt
2013-07-17 17:37 ` Oleg Nesterov
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