From: Andrii Nakryiko <andriin@fb.com>
Date: Wed, 11 Mar 2020 11:53:45 -0700
Subject: selftests/bpf: Guarantee that useep() calls nanosleep() syscall
Patch-mainline: v5.7-rc1
Git-commit: 2b5cf9fb74848fe5742a56e872e6847b79933c0b
References: bsc#1177028

Some implementations of C runtime library won't call nanosleep() syscall from
usleep(). But a bunch of kprobe/tracepoint selftests rely on nanosleep being
called to trigger them. To make this more reliable, "override" usleep
implementation and call nanosleep explicitly.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Julia Kartseva <hex@fb.com>
Link: https://lore.kernel.org/bpf/20200311185345.3874602-1-andriin@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Gary Lin <glin@suse.com>
---
 tools/testing/selftests/bpf/test_progs.c |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -29,6 +29,15 @@ struct prog_test_def {
 	int old_error_cnt;
 };
 
+/* Override C runtime library's usleep() implementation to ensure nanosleep()
+ * is always called. Usleep is frequently used in selftests as a way to
+ * trigger kprobe and tracepoints.
+ */
+int usleep(useconds_t usec)
+{
+	return syscall(__NR_nanosleep, usec * 1000UL);
+}
+
 static bool should_run(struct test_selector *sel, int num, const char *name)
 {
 	int i;