Re: [PATCH net 2/2] selftests/net: add SO_RESERVE_MEM test

Hi Eric,

Thank you for the new test.

On 25/09/2026 14:49, netdev-bot+sashiko@kernel.org wrote:

Thank you for your contribution! Sashiko AI review found 6 potential
issue(s) to consider.

(...)

quoted

+static void check_non_tcp_rejected(struct __test_metadata *_metadata,
+				   int domain, int type, int protocol,
+				   int val)
+{
+	int fd = socket(domain, type, protocol);
+
+	if (fd < 0) {
+		EXPECT_TRUE(errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT);
+		return;
+	}

[Severity: Medium]
Should ENOPROTOOPT be accepted here as well?

MPTCP can be built in but disabled with net.mptcp.enabled=0. In that case
socket creation fails here:

net/mptcp/protocol.c:mptcp_init_sock() {
	...
	if (!mptcp_is_enabled(net))
		return -ENOPROTOOPT;
	...
}

inet_create() passes that error back to userspace. As a result,
socket(AF_INET, SOCK_STREAM, IPPROTO_MPTCP) in non_tcp_rejected fails with
ENOPROTOOPT, and the EXPECT_TRUE fails the test.

The test doesn't unshare the network namespace, so it sees the host's
sysctl. Any other environment-specific socket() errno also becomes an
EXPECT failure rather than a skip.

Typically, we try to run the tests in a dedicated netns to avoid such
issues. (We also force net.mptcp.enabled=1 because it is still disabled
on RHEL, which is really a shame... but I don't think we really need to
support that here in the selftests.)

At the end, I don't think we need to care about all possible cases, but
using a netns is probably a good idea, at least not to "poison" other
tests. (If that's easy to put in place.)

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.