Free each probe event data structure asynchronously when
deleting probe events. But this finally synchronizes RCU
so that we make sure all event handlers have finished.
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
kernel/trace/trace_dynevent.c | 5 ++++
kernel/trace/trace_kprobe.c | 46 +++++++++++++++++++++++++++++++++++------
2 files changed, 44 insertions(+), 7 deletions(-)
diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index 89779eb84a07..2d5e8d457309 100644
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -70,6 +70,9 @@ int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type)
if (ret)
break;
}
+
+ /* Wait for running events because of async event unregistration */
+ synchronize_rcu();
mutex_unlock(&event_mutex);
return ret;
@@ -164,6 +167,8 @@ int dyn_events_release_all(struct dyn_event_operations *type)
if (ret)
break;
}
+ /* Wait for running events because of async event unregistration */
+ synchronize_rcu();
out:
mutex_unlock(&event_mutex);
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 906af1ffe2b2..f7e0370b10ae 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -551,7 +551,35 @@ static void __unregister_trace_kprobe(struct trace_kprobe *tk)
}
}
-/* Unregister a trace_probe and probe_event */
+static void free_trace_kprobe_cb(struct rcu_head *head)
+{
+ struct kprobe *kp = container_of(head, struct kprobe, rcu);
+ struct kretprobe *rp = container_of(kp, struct kretprobe, kp);
+ struct trace_kprobe *tk = container_of(rp, struct trace_kprobe, rp);
+
+ if (trace_kprobe_is_return(tk))
+ kretprobe_free_callback(head);
+ else
+ kprobe_free_callback(head);
+ free_trace_kprobe(tk);
+}
+
+static void __unregister_trace_kprobe_async(struct trace_kprobe *tk)
+{
+ if (trace_kprobe_is_registered(tk)) {
+ if (trace_kprobe_is_return(tk))
+ unregister_kretprobe_async(&tk->rp,
+ free_trace_kprobe_cb);
+ else
+ unregister_kprobe_async(&tk->rp.kp,
+ free_trace_kprobe_cb);
+ }
+}
+
+/*
+ * Unregister a trace_probe and probe_event asynchronously.
+ * Caller must wait for RCU.
+ */
static int unregister_trace_kprobe(struct trace_kprobe *tk)
{
/* If other probes are on the event, just unregister kprobe */
@@ -570,9 +598,17 @@ static int unregister_trace_kprobe(struct trace_kprobe *tk)
return -EBUSY;
unreg:
- __unregister_trace_kprobe(tk);
dyn_event_remove(&tk->devent);
+ /*
+ * This trace_probe_unlink() can free the trace_event_call linked to
+ * this probe.
+ * We can do this before unregistering because this probe is
+ * already disabled and the disabling process waits enough period
+ * for all handlers finished. IOW, the disabling process must wait
+ * RCU sync at least once before returning to its caller.
+ */
trace_probe_unlink(&tk->tp);
+ __unregister_trace_kprobe_async(tk);
return 0;
}
@@ -928,11 +964,7 @@ static int create_or_delete_trace_kprobe(int argc, char **argv)
static int trace_kprobe_release(struct dyn_event *ev)
{
struct trace_kprobe *tk = to_trace_kprobe(ev);
- int ret = unregister_trace_kprobe(tk);
-
- if (!ret)
- free_trace_kprobe(tk);
- return ret;
+ return unregister_trace_kprobe(tk);
}
static int trace_kprobe_show(struct seq_file *m, struct dyn_event *ev)
