[PATCH] [ssdd] add ptrace tierdown for the tests

[Attila Fazekas <afazekas@redhat.com>]

Without tierdown the tracee can receive SIGTRAP
leading to multiple core dumps being created.
At higher concurrency you may also see

coredump: 11747(ssdd): over core_pipe_limit, skipping core dump

in the dmesg with
kernel.core_pattern = |/usr/lib/systemd/systemd-coredump %P %u %g %s %t %c %h %d %F
kernel.core_pipe_limit = 16

Signed-off-by: Attila Fazekas <afazekas@redhat.com>
---
 src/ssdd/ssdd.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/ssdd/ssdd.c b/src/ssdd/ssdd.c
index 63130cd..61aab84 100644
--- a/src/ssdd/ssdd.c
+++ b/src/ssdd/ssdd.c
@@ -312,9 +312,23 @@ static int forktests(int testid)
 		got_sigchld = 0;
 	}
 
-	/* There is no need for the tracer to kill the tracee. It will
-	 * automatically exit when its owner, ie, us, exits.
+	/* The tracee can receive SIGTRAP(dump) without detaching.
 	 */
+	pstatus = ptrace(PTRACE_DETACH, child, NULL, NULL);
+	if (pstatus == ~0l) {
+		printf("forktest#%d/%d: EXITING, ERROR: "
+		       "detach failed.  errno %d\n",
+		       testid, getpid(), errno);
+		exit(1);
+	}
+	pstatus = kill(child, SIGKILL);
+	if (pstatus != 0) {
+		printf("forktest#%d/%d: EXITING, ERROR: "
+		       "kill failed.  errno %d\n",
+                       testid, getpid(), errno);
+		exit(1);
+	}
+
 	if (!quiet)
 		printf("forktest#%d/%d: EXITING, no error\n", testid, parent);
 	exit(0);
-- 
2.52.0