tracing/kprobes: 'nmissed' not showed correctly for kretprobe

The 'nmissed' column of the 'kprobe_profile' file for kretprobe is
not showed correctly, kretprobe can be skipped by two reasons,
shortage of kretprobe_instance which is counted by tk->rp.nmissed,
and kprobe itself is missed by some reason, so to show the sum.

Link: https://lkml.kernel.org/r/[email protected]

Cc: [email protected]
Fixes: 4a846b4 ("tracing/kprobes: Cleanup kprobe tracer code")
Acked-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Xiangyang Zhang <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>

Author: shellbombs

kernel/trace/trace_kprobe.c

@@ -1170,15 +1170,18 @@ static int probes_profile_seq_show(struct seq_file *m, void *v)
 {
 	struct dyn_event *ev = v;
 	struct trace_kprobe *tk;
+	unsigned long nmissed;
 
 	if (!is_trace_kprobe(ev))
 		return 0;
 
 	tk = to_trace_kprobe(ev);
+	nmissed = trace_kprobe_is_return(tk) ?
+		tk->rp.kp.nmissed + tk->rp.nmissed : tk->rp.kp.nmissed;
 	seq_printf(m, "  %-44s %15lu %15lu\n",
 		   trace_probe_name(&tk->tp),
 		   trace_kprobe_nhit(tk),
-		   tk->rp.kp.nmissed);
+		   nmissed);
 
 	return 0;
 }