Some tests, like tc_tunnel or tc_edt, sporadically fail in CI with the
following logs:

  (network_helpers.c:309: errno: Operation now in progress) \
    Failed to connect to server
  send_and_test_data:FAIL:connect to server unexpected error: -115

This is due to SO_RCVTIMEO and SO_SNDTIMEO being set on the client
socket (see settimeo() in client_socket()), allowing connect() to return
an error and to set errno to EINPROGRESS instead of ETIMEDOUT.
Increasing the timeout value for those tests is likely not a good
solution (and it has already been done by commit 2790db208b44
("selftests/bpf: Improve tc_tunnel test reliability")): some tests
expect some data transfer to fail, and so the timeout value would
increase overall test execution duration again (not only the connection,
but any socket operation).

Another solution is to allocate a timeout budget specific to the
connection: we can apply a larger timeout only for connections, and once
the connection is established, set back the timeout configured through
opts->timeout_ms; this would allow connection to succeed under heavy CI
load, while keeping timeout reasonable for the rest of the test traffic.

Create a dedicated connect helper that sets a large timeout for the
connect step, tries to connect, and if successful, finally sets the
timeout value to the one configured by the test.

Fixes: 99126abec5e5 ("bpf: selftests: A few improvements to network_helpers.c")
Acked-by: Ihor Solodrai <[email protected]>
Signed-off-by: Alexis LothorĂ© (eBPF Foundation) <[email protected]>
---
Hello,
this is the v5 of the series aiming to reduce the flakyness of
tc_tunnel/tc_edt tests in CI. This revision refactor a bit the new
connect timeout logic, and makes sure to apply the new logic to the
other connect() call in connect_fd_to_fd, as suggested by Daniel.
---
Changes in v6:
- Factor settimeo/connect/settimeo in a dedicated helper
- Apply the same strategy to connect_fd_to_fd
- drop comment-style updated patch, applied separately by Daniel
- Link to v5: 
https://patch.msgid.link/[email protected]

Changes in v5:
- reformat multi-line comments
- collect Ihor's Acked-by
- Link to v4: 
https://patch.msgid.link/[email protected]

Changes in v4:
- dropped the polling loop in favor of a larger, connect-specific timeout
- drop timeout configuration from tc_edt test
- Link to v3: 
https://patch.msgid.link/[email protected]

Changes in v3:
- set errno before logging errors
- respect time budget set by
- respect opts->timeout_ms when polling: only poll for the remaining
  time not already consume by connect()
- keep polling if poll returns with EINTR
- reorder early returns and add intermediate variables to clarify code
  flow
- Link to v2: 
https://patch.msgid.link/[email protected]

Changes in v2:
- drop unneeded initialization
- add back error message for immediate connection failure, and slightly
  reword the async connection failure error message
- Link to v1: 
https://patch.msgid.link/[email protected]

To: Alexei Starovoitov <[email protected]>
To: Daniel Borkmann <[email protected]>
To: Andrii Nakryiko <[email protected]>
To: Eduard Zingerman <[email protected]>
To: Kumar Kartikeya Dwivedi <[email protected]>
To: Martin KaFai Lau <[email protected]>
To: Song Liu <[email protected]>
To: Yonghong Song <[email protected]>
To: Jiri Olsa <[email protected]>
To: Emil Tsalapatis <[email protected]>
To: Ihor Solodrai <[email protected]>
To: Shuah Khan <[email protected]>
Cc: [email protected]
Cc: Bastien Curutchet <[email protected]>
Cc: Thomas Petazzoni <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
 tools/testing/selftests/bpf/network_helpers.c | 48 +++++++++++++++++++++------
 1 file changed, 37 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/bpf/network_helpers.c 
b/tools/testing/selftests/bpf/network_helpers.c
index cdf2d7d3ab32..9f6abc4dd273 100644
--- a/tools/testing/selftests/bpf/network_helpers.c
+++ b/tools/testing/selftests/bpf/network_helpers.c
@@ -49,6 +49,8 @@
                        errno = __save;                                 \
 })
 
+#define CONNECT_MIN_TIMEOUT_MS 5000
+
 struct ipv4_packet pkt_v4 = {
        .eth.h_proto = __bpf_constant_htons(ETH_P_IP),
        .iph.ihl = 5,
@@ -291,6 +293,37 @@ int client_socket(int family, int type,
        return -1;
 }
 
+static int connect_with_timeout(int fd, const struct sockaddr_storage *addr,
+                               socklen_t addrlen, int timeout_ms)
+{
+       int connect_timeout_ms = MAX(timeout_ms, CONNECT_MIN_TIMEOUT_MS);
+
+       /*
+        * Override timeout configuration with a larger value for the
+        * connection
+        */
+       if (settimeo(fd, connect_timeout_ms)) {
+               log_err("Failed to set connect timeout");
+               return -1;
+       }
+
+       if (connect(fd, (const struct sockaddr *)addr, addrlen)) {
+               log_err("Failed to connect");
+               return -1;
+       }
+
+       /*
+        * If the timeout configured by the test is different from the
+        * connect timeout, restore it
+        */
+       if (timeout_ms != connect_timeout_ms && settimeo(fd, timeout_ms)) {
+               log_err("Failed to set timeout for connected socket");
+               return -1;
+       }
+
+       return 0;
+}
+
 int connect_to_addr(int type, const struct sockaddr_storage *addr, socklen_t 
addrlen,
                    const struct network_helper_opts *opts)
 {
@@ -305,8 +338,7 @@ int connect_to_addr(int type, const struct sockaddr_storage 
*addr, socklen_t add
                return -1;
        }
 
-       if (connect(fd, (const struct sockaddr *)addr, addrlen)) {
-               log_err("Failed to connect to server");
+       if (connect_with_timeout(fd, addr, addrlen, opts->timeout_ms)) {
                save_errno_close(fd);
                return -1;
        }
@@ -376,20 +408,14 @@ int connect_fd_to_fd(int client_fd, int server_fd, int 
timeout_ms)
        struct sockaddr_storage addr;
        socklen_t len = sizeof(addr);
 
-       if (settimeo(client_fd, timeout_ms))
-               return -1;
-
        if (getsockname(server_fd, (struct sockaddr *)&addr, &len)) {
                log_err("Failed to get server addr");
                return -1;
        }
 
-       if (connect(client_fd, (const struct sockaddr *)&addr, len)) {
-               log_err("Failed to connect to server");
-               return -1;
-       }
-
-       return 0;
+       return connect_with_timeout(client_fd,
+                                   &addr, len,
+                                   timeout_ms);
 }
 
 int make_sockaddr(int family, const char *addr_str, __u16 port,

---
base-commit: 23ff631b3b8b1452dfe933ee21f96321a9c5e209
change-id: 20260710-tc_tunnel_flaky-27e9a191bd03

Best regards,
--  
Alexis LothorĂ© (eBPF Foundation) <[email protected]>


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