[PATCH bpf-next v2] selftests/bpf: Add F_SETFL for fcntl

[Geliang Tang <geliang@kernel.org>]

From: Geliang Tang <tanggeliang@kylinos.cn>

Incorrect arguments are passed to fcntl() in test_sockmap.c when invoking
it to set file status flags. If O_NONBLOCK is used as 2nd argument and
passed into fcntl, -EINVAL will be returned (See do_fcntl() in fs/fcntl.c).
The correct approach is to use F_SETFL as 2nd argument, and O_NONBLOCK as
3rd one.

In nonblock mode, if EWOULDBLOCK is received, receive again, otherwise some
subtests of test_sockmap will fail.

Fixes: 16962b2404ac ("bpf: sockmap, add selftests")
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 v2:
 - fix errors:
# 6/ 7  sockmap::txmsg test skb:FAIL
#21/ 7 sockhash::txmsg test skb:FAIL
#36/ 7 sockhash:ktls:txmsg test skb:FAIL
Pass: 42 Fail: 3
---
 tools/testing/selftests/bpf/test_sockmap.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/test_sockmap.c b/tools/testing/selftests/bpf/test_sockmap.c
index 024a0faafb3b..bbc3fd57f349 100644
--- a/tools/testing/selftests/bpf/test_sockmap.c
+++ b/tools/testing/selftests/bpf/test_sockmap.c
@@ -603,7 +603,7 @@ static int msg_loop(int fd, int iov_count, int iov_length, int cnt,
 		struct timeval timeout;
 		fd_set w;
 
-		fcntl(fd, fd_flags);
+		fcntl(fd, F_SETFL, fd_flags);
 		/* Account for pop bytes noting each iteration of apply will
 		 * call msg_pop_data helper so we need to account for this
 		 * by calculating the number of apply iterations. Note user
@@ -671,12 +671,15 @@ static int msg_loop(int fd, int iov_count, int iov_length, int cnt,
 				flags = 0;
 			}
 
+again:
 			recv = recvmsg(fd, &msg, flags);
 			if (recv < 0) {
 				if (errno != EWOULDBLOCK) {
 					clock_gettime(CLOCK_MONOTONIC, &s->end);
 					perror("recv failed()");
 					goto out_errno;
+				} else {
+					goto again;
 				}
 			}
 
-- 
2.40.1