From 9edb3e1bebd4387eeb00aefc7ea4486989d5dbc6 Mon Sep 17 00:00:00 2001
From: Javier Honduvilla Coto <javierhonduco@gmail.com>
Date: Mon, 25 Mar 2019 23:35:41 +0000
Subject: [PATCH] usdt: add hint when pid is not running

---
 src/list.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/list.cpp b/src/list.cpp
index cdadddf90f0..3a27ff1a4d9 100644
--- a/src/list.cpp
+++ b/src/list.cpp
@@ -1,3 +1,4 @@
+#include <signal.h>
 #include <sys/types.h>
 #include <dirent.h>
 #include <fstream>
@@ -148,6 +149,9 @@ void list_probes(const std::string &search_input, int pid)
     void *ctx = bcc_usdt_new_frompid(pid, nullptr);
     if (ctx == nullptr) {
       std::cerr << "failed to initialize usdt context for pid: " << pid << std::endl;
+      if (kill(pid, 0) == -1 && errno == ESRCH) {
+        std::cerr << "hint: process not running" << std::endl;
+      }
       return;
     }
     bcc_usdt_foreach(ctx, usdt_each);