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

BugLink: https://bugs.launchpad.net/bugs/1960566
commit dfea08a2116fe327f79d8f4d4b2cf6e0c88be11f upstream.

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/20220107150242.5019-1-xyz.sun.ok@gmail.com
Cc: stable@vger.kernel.org
Fixes: 4a846b443b4e ("tracing/kprobes: Cleanup kprobe tracer code")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Xiangyang Zhang <xyz.sun.ok@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 5de084dab4fa65dc30a663d57af86d73ef971581..13ccf2f28987e9d70b615f0692d7b924a3877218 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -999,15 +999,18 @@ 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;
 }