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tracing/kprobe: Wait for disabling all running kprobe handlers

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commit a232e270dc upstream.

Wait for disabling all running kprobe handlers when a kprobe
event is disabled, since the caller, trace_remove_event_call()
supposes that a removing event is disabled completely by
disabling the event.
With this change, ftrace can ensure that there is no running
event handlers after disabling it.

Link: http://lkml.kernel.org/r/20130709093526.20138.93100.stgit@mhiramat-M0-7522

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Masami Hiramatsu 2013-07-09 18:35:26 +09:00 • committed by Greg Kroah-Hartman
commit e899e7e4f8
1 changed files with 17 additions and 4 deletions
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21
kernel/trace/trace_kprobe.c
View file

@ -281,6 +281,8 @@ trace_probe_file_index(struct trace_probe *tp, struct ftrace_event_file *file)
static int
disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
{
struct ftrace_event_file **old = NULL;
int wait = 0;
int ret = 0;
mutex_lock(&probe_enable_lock);
@ -314,10 +316,7 @@ disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
}
rcu_assign_pointer(tp->files, new);
/* Make sure the probe is done with old files */
synchronize_sched();
kfree(old);
wait = 1;
} else
tp->flags &= ~TP_FLAG_PROFILE;
@ -326,11 +325,25 @@ disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
disable_kretprobe(&tp->rp);
else
disable_kprobe(&tp->rp.kp);
wait = 1;
}
out_unlock:
mutex_unlock(&probe_enable_lock);
if (wait) {
/*
* Synchronize with kprobe_trace_func/kretprobe_trace_func
* to ensure disabled (all running handlers are finished).
* This is not only for kfree(), but also the caller,
* trace_remove_event_call() supposes it for releasing
* event_call related objects, which will be accessed in
* the kprobe_trace_func/kretprobe_trace_func.
*/
synchronize_sched();
kfree(old); /* Ignored if link == NULL */
}
return ret;
}