linux-kernel - [PATCH bpf-next 1/5] selftests/bpf: sockmap_redir: Simplify try

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Message-Id: <20250905-redir-test-pass-drop-v1-1-9d9e43ff40df@rbox.co>
Date: Fri, 05 Sep 2025 13:11:41 +0200
From: Michal Luczaj <mhal@...x.co>
To: Alexei Starovoitov <ast@...nel.org>, 
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, 
 Martin KaFai Lau <martin.lau@...ux.dev>, 
 Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
 Yonghong Song <yonghong.song@...ux.dev>, 
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, 
 Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
 Jiri Olsa <jolsa@...nel.org>, Mykola Lysenko <mykolal@...com>, 
 Shuah Khan <shuah@...nel.org>
Cc: bpf@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Michal Luczaj <mhal@...x.co>
Subject: [PATCH bpf-next 1/5] selftests/bpf: sockmap_redir: Simplify
 try_recv()

try_recv() was meant to support both @expect_success cases, but all the
callers use @expect_success=false anyway. Drop the unused logic and fold in
MSG_DONTWAIT. Adapt callers.

Subtle change here: recv() return value of 0 will also be considered (an
unexpected) success.

Signed-off-by: Michal Luczaj <mhal@...x.co>
---
 .../selftests/bpf/prog_tests/sockmap_redir.c       | 25 +++++++++-------------
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_redir.c b/tools/testing/selftests/bpf/prog_tests/sockmap_redir.c
index 9c461d93113db20de65ac353f92dfdbe32ffbd3b..c1bf1076e8152b7d83c3e07e2dce746b5a39cf7e 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockmap_redir.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_redir.c
@@ -144,17 +144,14 @@ static void get_redir_params(struct redir_spec *redir,
 		*redirect_flags = 0;
 }
 
-static void try_recv(const char *prefix, int fd, int flags, bool expect_success)
+static void fail_recv(const char *prefix, int fd, int more_flags)
 {
 	ssize_t n;
 	char buf;
 
-	errno = 0;
-	n = recv(fd, &buf, 1, flags);
-	if (n < 0 && expect_success)
-		FAIL_ERRNO("%s: unexpected failure: retval=%zd", prefix, n);
-	if (!n && !expect_success)
-		FAIL("%s: expected failure: retval=%zd", prefix, n);
+	n = recv(fd, &buf, 1, MSG_DONTWAIT | more_flags);
+	if (n >= 0)
+		FAIL("%s: unexpected success: retval=%zd", prefix, n);
 }
 
 static void handle_unsupported(int sd_send, int sd_peer, int sd_in, int sd_out,
@@ -188,13 +185,13 @@ static void handle_unsupported(int sd_send, int sd_peer, int sd_in, int sd_out,
 	}
 
 	/* Ensure queues are empty */
-	try_recv("bpf.recv(sd_send)", sd_send, MSG_DONTWAIT, false);
+	fail_recv("bpf.recv(sd_send)", sd_send, 0);
 	if (sd_in != sd_send)
-		try_recv("bpf.recv(sd_in)", sd_in, MSG_DONTWAIT, false);
+		fail_recv("bpf.recv(sd_in)", sd_in, 0);
 
-	try_recv("bpf.recv(sd_out)", sd_out, MSG_DONTWAIT, false);
+	fail_recv("bpf.recv(sd_out)", sd_out, 0);
 	if (sd_recv != sd_out)
-		try_recv("bpf.recv(sd_recv)", sd_recv, MSG_DONTWAIT, false);
+		fail_recv("bpf.recv(sd_recv)", sd_recv, 0);
 }
 
 static void test_send_redir_recv(int sd_send, int send_flags, int sd_peer,
@@ -257,15 +254,13 @@ static void test_send_redir_recv(int sd_send, int send_flags, int sd_peer,
 
 	if (send_flags & MSG_OOB) {
 		/* Fail reading OOB while in sockmap */
-		try_recv("bpf.recv(sd_out, MSG_OOB)", sd_out,
-			 MSG_OOB | MSG_DONTWAIT, false);
+		fail_recv("bpf.recv(sd_out, MSG_OOB)", sd_out, MSG_OOB);
 
 		/* Remove sd_out from sockmap */
 		xbpf_map_delete_elem(maps->out, &u32(0));
 
 		/* Check that OOB was dropped on redirect */
-		try_recv("recv(sd_out, MSG_OOB)", sd_out,
-			 MSG_OOB | MSG_DONTWAIT, false);
+		fail_recv("recv(sd_out, MSG_OOB)", sd_out, MSG_OOB);
 
 		goto del_in;
 	}

-- 
2.50.1