[RESEND PATCH v2 bpf-next 09/12] selftests/bpf: Make ehash buckets configurable in socket iterator tests

[Jordan Rife <jordan@jrife.io>]

Prepare for bucket resume tests for established TCP sockets by making
the number of ehash buckets configurable. Subsequent patches force all
established sockets into the same bucket by setting ehash_buckets to
one.

Signed-off-by: Jordan Rife <jordan@jrife.io>
---
 .../bpf/prog_tests/sock_iter_batch.c          | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/sock_iter_batch.c b/tools/testing/selftests/bpf/prog_tests/sock_iter_batch.c
index afe0f55ead75..4c145c5415f1 100644
--- a/tools/testing/selftests/bpf/prog_tests/sock_iter_batch.c
+++ b/tools/testing/selftests/bpf/prog_tests/sock_iter_batch.c
@@ -6,6 +6,7 @@
 #include "sock_iter_batch.skel.h"
 
 #define TEST_NS "sock_iter_batch_netns"
+#define TEST_CHILD_NS "sock_iter_batch_child_netns"
 
 static const int init_batch_size = 16;
 static const int nr_soreuse = 4;
@@ -304,6 +305,7 @@ struct test_case {
 		     int *socks, int socks_len, struct sock_count *counts,
 		     int counts_len, struct bpf_link *link, int iter_fd);
 	const char *description;
+	int ehash_buckets;
 	int init_socks;
 	int max_socks;
 	int sock_type;
@@ -410,13 +412,25 @@ static struct test_case resume_tests[] = {
 static void do_resume_test(struct test_case *tc)
 {
 	struct sock_iter_batch *skel = NULL;
+	struct sock_count *counts = NULL;
 	static const __u16 port = 10001;
+	struct nstoken *nstoken = NULL;
 	struct bpf_link *link = NULL;
-	struct sock_count *counts;
 	int err, iter_fd = -1;
 	const char *addr;
 	int *fds = NULL;
 
+	if (tc->ehash_buckets) {
+		SYS_NOFAIL("ip netns del " TEST_CHILD_NS);
+		SYS(done, "sysctl -w net.ipv4.tcp_child_ehash_entries=%d",
+		    tc->ehash_buckets);
+		SYS(done, "ip netns add %s", TEST_CHILD_NS);
+		SYS(done, "ip -net %s link set dev lo up", TEST_CHILD_NS);
+		nstoken = open_netns(TEST_CHILD_NS);
+		if (!ASSERT_OK_PTR(nstoken, "open_child_netns"))
+			goto done;
+	}
+
 	counts = calloc(tc->max_socks, sizeof(*counts));
 	if (!ASSERT_OK_PTR(counts, "counts"))
 		goto done;
@@ -453,6 +467,9 @@ static void do_resume_test(struct test_case *tc)
 	tc->test(tc->family, tc->sock_type, addr, port, fds, tc->init_socks,
 		 counts, tc->max_socks, link, iter_fd);
 done:
+	close_netns(nstoken);
+	SYS_NOFAIL("ip netns del " TEST_CHILD_NS);
+	SYS_NOFAIL("sysctl -w net.ipv4.tcp_child_ehash_entries=0");
 	free(counts);
 	free_fds(fds, tc->init_socks);
 	if (iter_fd >= 0)
-- 
2.43.0