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authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>2013-07-09 18:35:26 +0900
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-29 09:47:32 -0700
commite899e7e4f83ecd606e85d355410d724ec76542cb (patch)
treeeca9720c6879e4726969b1e597271c0eb56e8821
parentb0cfaffa7e183719436a7a2b1b814afb5748c05c (diff)
downloadvexpress-lsk-e899e7e4f83ecd606e85d355410d724ec76542cb.tar.gz
tracing/kprobe: Wait for disabling all running kprobe handlers
commit a232e270dcb55a70ad3241bc6fc160fd9b5c9e6c 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>
-rw-r--r--kernel/trace/trace_kprobe.c21
1 files changed, 17 insertions, 4 deletions
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 9f46e98ba8f..c209c6ec34c 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -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;
}