From: Geliang Tang <tanggeliang@kylinos.cn>

Replace /dev/urandom with getrandom() for initializing the RNG. This
simplifies the code and avoids potential failures from opening device
files while maintaining cryptographic quality randomness.

These codes are from mptcp_inq.c.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 .../selftests/net/mptcp/mptcp_sockopt.c       | 20 +++++++------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
index e934dd26a59d..2bd75f731dfd 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
@@ -20,6 +20,7 @@
 #include <sys/socket.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <sys/random.h>
 
 #include <netdb.h>
 #include <netinet/in.h>
@@ -815,21 +816,14 @@ static int rcheck(int wstatus, const char *what)
 
 static void init_rng(void)
 {
-	int fd = open("/dev/urandom", O_RDONLY);
+	unsigned int foo;
 
-	if (fd >= 0) {
-		unsigned int foo;
-		ssize_t ret;
-
-		/* can't fail */
-		ret = read(fd, &foo, sizeof(foo));
-		assert(ret == sizeof(foo));
-
-		close(fd);
-		srand(foo);
-	} else {
-		srand(time(NULL));
+	if (getrandom(&foo, sizeof(foo), 0) == -1) {
+		perror("getrandom");
+		exit(1);
 	}
+
+	srand(foo);
 }
 
 int main(int argc, char *argv[])
-- 
2.48.1