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[RESEND,bpf,v3,2/8] selftests/bpf: Retry for EAGAIN in udp_redir_to_connected()

Message ID 20210615021342.7416-3-xiyou.wangcong@gmail.com (mailing list archive)
State Accepted
Commit a7e65fe7d8201527129206754db1a2db6a6b2fde
Delegated to: BPF
Headers show
Series sock_map: some bug fixes and improvements | expand


Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
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netdev/tree_selection success Clearly marked for bpf
netdev/subject_prefix success Link
netdev/cc_maintainers fail 1 blamed authors not CCed: ast@kernel.org; 8 maintainers not CCed: linux-kselftest@vger.kernel.org yhs@fb.com kpsingh@kernel.org andrii@kernel.org kafai@fb.com ast@kernel.org songliubraving@fb.com shuah@kernel.org
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
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netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 21 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success Link

Commit Message

Cong Wang June 15, 2021, 2:13 a.m. UTC
From: Cong Wang <cong.wang@bytedance.com>

We use non-blocking sockets for testing sockmap redirections,
and got some random EAGAIN errors from UDP tests.

There is no guarantee the packet would be immediately available
to receive as soon as it is sent out, even on the local host.
For UDP, this is especially true because it does not lock the
sock during BH (unlike the TCP path). This is probably why we
only saw this error in UDP cases.

No matter how hard we try to make the queue empty check accurate,
it is always possible for recvmsg() to beat ->sk_data_ready().
Therefore, we should just retry in case of EAGAIN.

Fixes: d6378af615275 ("selftests/bpf: Add a test case for udp sockmap")
Reported-by: Jiang Wang <jiang.wang@bytedance.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
 tools/testing/selftests/bpf/prog_tests/sockmap_listen.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
diff mbox series


diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c b/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c
index 648d9ae898d2..01ab11259809 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c
@@ -1610,6 +1610,7 @@  static void udp_redir_to_connected(int family, int sotype, int sock_mapfd,
 	struct sockaddr_storage addr;
 	int c0, c1, p0, p1;
 	unsigned int pass;
+	int retries = 100;
 	socklen_t len;
 	int err, n;
 	u64 value;
@@ -1686,9 +1687,13 @@  static void udp_redir_to_connected(int family, int sotype, int sock_mapfd,
 	if (pass != 1)
 		FAIL("%s: want pass count 1, have %d", log_prefix, pass);
 	n = read(mode == REDIR_INGRESS ? p0 : c0, &b, 1);
-	if (n < 0)
+	if (n < 0) {
+		if (errno == EAGAIN && retries--)
+			goto again;
 		FAIL_ERRNO("%s: read", log_prefix);
+	}
 	if (n == 0)
 		FAIL("%s: incomplete read", log_prefix);