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 2/4] tracing: trace_remove_event_call() should fail if call/file is in use
Date: Thu, 04 Jul 2013 21:48:41 +0900 [thread overview]
Message-ID: <51D56F29.2040700@hitachi.com> (raw)
In-Reply-To: <20130704034038.665930010@goodmis.org>
(2013/07/04 12:33), Steven Rostedt wrote:
> From: Oleg Nesterov <oleg@redhat.com>
>
> Change trace_remove_event_call(call) to return the error if this
> call is active. This is what the callers assume but can't verify
> outside of the tracing locks. Both trace_kprobe.c/trace_uprobe.c
> need the additional changes, unregister_trace_probe() should abort
> if trace_remove_event_call() fails.
>
> We also check TRACE_EVENT_FL_REF_MASK to ensure that nobody opened
> the files we are going to remove, these means that nobody can access
> the soon-to-be-freed ftrace_event_file/call via filp->private_data.
>
> Link: http://lkml.kernel.org/r/20130702222359.GA27629@redhat.com
This looks good for me ;)
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Thanks!
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
> include/linux/ftrace_event.h | 2 +-
> kernel/trace/trace_events.c | 33 +++++++++++++++++++++++++++++++--
> 2 files changed, 32 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
> index 72ff2c6..bdf6bdd 100644
> --- a/include/linux/ftrace_event.h
> +++ b/include/linux/ftrace_event.h
> @@ -338,7 +338,7 @@ extern int trace_define_field(struct ftrace_event_call *call, const char *type,
> const char *name, int offset, int size,
> int is_signed, int filter_type);
> extern int trace_add_event_call(struct ftrace_event_call *call);
> -extern void trace_remove_event_call(struct ftrace_event_call *call);
> +extern int trace_remove_event_call(struct ftrace_event_call *call);
>
> #define is_signed_type(type) (((type)(-1)) < (type)1)
>
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 90cf243..1a5547e 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -1766,16 +1766,45 @@ static void __trace_remove_event_call(struct ftrace_event_call *call)
> destroy_preds(call);
> }
>
> +static int probe_remove_event_call(struct ftrace_event_call *call)
> +{
> + struct trace_array *tr;
> + struct ftrace_event_file *file;
> +
> + if (call->flags & TRACE_EVENT_FL_REF_MASK)
> + return -EBUSY;
> +
> +#ifdef CONFIG_PERF_EVENTS
> + if (call->perf_refcount)
> + return -EBUSY;
> +#endif
> + do_for_each_event_file(tr, file) {
> + if (file->event_call != call)
> + continue;
> + if (file->flags & FTRACE_EVENT_FL_ENABLED)
> + return -EBUSY;
> + break;
> + } while_for_each_event_file();
> +
> + __trace_remove_event_call(call);
> +
> + return 0;
> +}
> +
> /* Remove an event_call */
> -void trace_remove_event_call(struct ftrace_event_call *call)
> +int trace_remove_event_call(struct ftrace_event_call *call)
> {
> + int ret;
> +
> mutex_lock(&trace_types_lock);
> mutex_lock(&event_mutex);
> down_write(&trace_event_sem);
> - __trace_remove_event_call(call);
> + ret = probe_remove_event_call(call);
> up_write(&trace_event_sem);
> mutex_unlock(&event_mutex);
> mutex_unlock(&trace_types_lock);
> +
> + return ret;
> }
>
> #define for_each_event(event, start, end) \
>
--
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 12:49 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 [this message]
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 ` [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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