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 3/4] tracing/kprobes: Fail to unregister if probe event files are open
Date: Tue, 30 Jul 2013 17:15:42 +0900 [thread overview]
Message-ID: <51F7762E.7010906@hitachi.com> (raw)
In-Reply-To: <20130704034038.819592356@goodmis.org>
(2013/07/04 12:33), Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
>
> When one of the event files is opened, we need to prevent them from
> being removed. Modules do with with the module owner set (automated
> from the VFS layer). The ftrace buffer instances have a ref count added
> to the trace_array when the enabled file is opened (the others are not
> that big of a deal, as they only reference the event calls which
> still exist when an instance disappears). But kprobes and uprobes
> do not have any protection.
>
> # 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
>
> Have the unregister probe fail when the event files are open, in use
> are used by perf.
>
Now, since the commit a232e270d makes sure that disable_trace_probe()
waits until all running handlers are done, this patch has no problem.
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Thank you!
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
> kernel/trace/trace_kprobe.c | 21 +++++++++++++++------
> 1 file changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 7ed6976..ffcaf42 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -95,7 +95,7 @@ static __kprobes bool trace_probe_is_on_module(struct trace_probe *tp)
> }
>
> static int register_probe_event(struct trace_probe *tp);
> -static void unregister_probe_event(struct trace_probe *tp);
> +static int unregister_probe_event(struct trace_probe *tp);
>
> static DEFINE_MUTEX(probe_lock);
> static LIST_HEAD(probe_list);
> @@ -340,9 +340,12 @@ static int unregister_trace_probe(struct trace_probe *tp)
> if (trace_probe_is_enabled(tp))
> return -EBUSY;
>
> + /* Will fail if probe is being used by ftrace or perf */
> + if (unregister_probe_event(tp))
> + return -EBUSY;
> +
> __unregister_trace_probe(tp);
> list_del(&tp->list);
> - unregister_probe_event(tp);
>
> return 0;
> }
> @@ -621,7 +624,9 @@ static int release_all_trace_probes(void)
> /* TODO: Use batch unregistration */
> while (!list_empty(&probe_list)) {
> tp = list_entry(probe_list.next, struct trace_probe, list);
> - unregister_trace_probe(tp);
> + ret = unregister_trace_probe(tp);
> + if (ret)
> + goto end;
> free_trace_probe(tp);
> }
>
> @@ -1242,11 +1247,15 @@ static int register_probe_event(struct trace_probe *tp)
> return ret;
> }
>
> -static void unregister_probe_event(struct trace_probe *tp)
> +static int unregister_probe_event(struct trace_probe *tp)
> {
> + int ret;
> +
> /* tp->event is unregistered in trace_remove_event_call() */
> - trace_remove_event_call(&tp->call);
> - kfree(tp->call.print_fmt);
> + ret = trace_remove_event_call(&tp->call);
> + if (!ret)
> + kfree(tp->call.print_fmt);
> + return ret;
> }
>
> /* Make a debugfs interface for controlling probe points */
>
--
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:[~2013-07-30 8:15 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 ` Masami Hiramatsu [this message]
2013-07-31 19:49 ` [RFC][PATCH 3/4] tracing/kprobes: Fail to unregister if probe event files are open 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 ` [RFC][PATCH 0/4] tracing/kprobes/uprobes: Fix race between opening probe event files and deleting probe Masami Hiramatsu
2013-07-04 6:14 ` 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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