[LTP] [PATCH 1/1] lib: Retry safe_clone() on ENOSPC|EUSERS

[Petr Vorel]

In some tests we are creating the namespaces faster than they are being
asynchronously cleaned up in the kernel. Thus retrying the clone() on
ENOSPC (or EUSERS for kernel < 4.9).

Before:
$ sudo ./userns08 -i 10
userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:65: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:36: TBROK: clone3 failed: ENOSPC (28)

With fix:
$ sudo ./userns08 -i 10
userns08.c:67: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:67: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:67: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:67: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:67: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:38: TINFO: clone3() failed => retrying: ENOSPC (28)
userns08.c:67: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:67: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:67: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:67: TPASS: Denied write access to ./restricted : EACCES (13)
userns08.c:67: TPASS: Denied write access to ./restricted : EACCES (13)

Suggested-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
 lib/tst_test.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/lib/tst_test.c b/lib/tst_test.c
index 384c73e163..527d265d0a 100644
--- a/lib/tst_test.c
+++ b/lib/tst_test.c
@@ -446,6 +446,14 @@ pid_t safe_clone(const char *file, const int lineno,
 
 	pid = tst_clone(args);
 
+	/* too fast creating namespaces => retrying */
+	if (pid < 0 && (errno == ENOSPC || errno == EUSERS)) {
+		tst_res_(file, lineno, TINFO | TERRNO, "%s() failed => retrying",
+				 pid == -2 ? "clone" : "clone3");
+		usleep(100000);
+		pid = tst_clone(args);
+	}
+
 	switch (pid) {
 	case -1:
 		tst_brk_(file, lineno, TBROK | TERRNO, "clone3 failed");
-- 
2.35.1