task_finder2: fix -ESRCH and -EALREADY registration errors

14313f350c7206e71e30a81dbc13a518f4bd1df9.patch

From 14313f350c7206e71e30a81dbc13a518f4bd1df9 Mon Sep 17 00:00:00 2001
From: Sultan Alsawaf <sultan@openresty.com>
Date: Wed, 30 Sep 2020 21:34:09 -0700
Subject: [PATCH] task_finder2: fix -ESRCH and -EALREADY registration errors

These errors appear to be non-fatal in this context. This fixes the
following errors:
ERROR: probe process("/usr/local/openresty/nginx/sbin/nginx").begin registration error (rc -114)
ERROR: probe process("/usr/local/openresty/nginx/sbin/nginx").begin registration error (rc -3)
---
 runtime/linux/task_finder2.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/runtime/linux/task_finder2.c b/runtime/linux/task_finder2.c
index 917ec46f1..d5662005c 100644
--- a/runtime/linux/task_finder2.c
+++ b/runtime/linux/task_finder2.c
@@ -569,6 +569,8 @@ __stp_utrace_attach(struct task_struct *tsk,
 		else if (rc != -ESRCH && rc != -EALREADY)
 			_stp_error("utrace_set_events2 returned error %d on pid %d",
 				   rc, (int)tsk->pid);
+		else
+			rc = 0;
 		utrace_engine_put(engine);
 	}
 	return rc;