On Fri, Jan 19, 2018 at 05:45:48PM -0800, Lawrence Brakmo wrote:

Added a selftest for tcpbpf (sock_ops) that checks that the appropriate
callbacks occured and that it can access tcp_sock fields and that their
values are correct.

Run with command: ./test_tcpbpf_user

Signed-off-by: Lawrence Brakmo <redacted>

...

+	__u32 key = 0;
+	struct tcpbpf_globals g, *gp;
+
+	gp = bpf_map_lookup_elem(&global_map, &key);
+	if (gp == NULL) {
+		struct tcpbpf_globals g = {0, 0, 0, 0, 0, 0, 0, 0};
+
+		g.event_map |= (1 << event);
+		bpf_map_update_elem(&global_map, &key, &g,
+			    BPF_ANY);
+	} else {
+		g = *gp;
+		g.event_map |= (1 << event);
+		bpf_map_update_elem(&global_map, &key, &g,
+			    BPF_ANY);

...

+			__u32 key = 0;
+			struct tcpbpf_globals g, *gp;
+
+			gp = bpf_map_lookup_elem(&global_map, &key);
+			if (!gp)
+				break;
+			g = *gp;
+			g.bad_cb_test_rv = bad_call_rv;
+			g.good_cb_test_rv = good_call_rv;
+			bpf_map_update_elem(&global_map, &key, &g,
+					    BPF_ANY);

since 'g' is an array of one element and the tests designed
for single flow anyway, there is no need to use map_update_elem.
the program can directly assign into fields like:
	gp->bad_cb_test_rv = bad_call_rv;
	gp->good_cb_test_rv = good_call_rv;
probably not worth respining just for that. Mainly fyi.
Acked-by: Alexei Starovoitov <ast@kernel.org>