Commit ef8c84ef authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Alexei Starovoitov
Browse files

selftests/bpf: De-flake test_tcpbpf 



It looks like BPF program that handles BPF_SOCK_OPS_STATE_CB state
can race with the bpf_map_lookup_elem("global_map"); I sometimes
see the failures in this test and re-running helps.

Since we know that we expect the callback to be called 3 times (one
time for listener socket, two times for both ends of the connection),
let's export this number and add simple retry logic around that.

Also, let's make EXPECT_EQ() not return on failure, but continue
evaluating all conditions; that should make potential debugging
easier.

With this fix in place I don't observe the flakiness anymore.

Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Cc: Lawrence Brakmo <brakmo@fb.com>
Link: https://lore.kernel.org/bpf/20191204190955.170934-1-sdf@google.com
parent 6bf6affe

tools/testing/selftests/bpf/progs/test_tcpbpf_kern.c

+1 −0
Original line number Diff line number Diff line
@@ -131,6 +131,7 @@ int bpf_testcb(struct bpf_sock_ops *skops) 
				g.bytes_received = skops->bytes_received;

				g.bytes_acked = skops->bytes_acked;

			}

			g.num_close_events++;

			bpf_map_update_elem(&global_map, &key, &g,

					    BPF_ANY);

		}

tools/testing/selftests/bpf/test_tcpbpf.h

+1 −0
Original line number Diff line number Diff line
@@ -13,5 +13,6 @@ struct tcpbpf_globals { 
	__u64 bytes_received;

	__u64 bytes_acked;

	__u32 num_listen;

	__u32 num_close_events;

};

#endif

tools/testing/selftests/bpf/test_tcpbpf_user.c

+18 −7
Original line number Diff line number Diff line
@@ -16,6 +16,9 @@ 


#include "test_tcpbpf.h"



/* 3 comes from one listening socket + both ends of the connection */

#define EXPECTED_CLOSE_EVENTS		3



#define EXPECT_EQ(expected, actual, fmt)			\

	do {							\

		if ((expected) != (actual)) {			\
@@ -23,13 +26,14 @@ 
			       "    Actual: %" fmt "\n"		\

			       "  Expected: %" fmt "\n",	\

			       (actual), (expected));		\

			goto err;				\

			ret--;					\

		}						\

	} while (0)



int verify_result(const struct tcpbpf_globals *result)

{

	__u32 expected_events;

	int ret = 0;



	expected_events = ((1 << BPF_SOCK_OPS_TIMEOUT_INIT) |

			   (1 << BPF_SOCK_OPS_RWND_INIT) |
@@ -48,15 +52,15 @@ int verify_result(const struct tcpbpf_globals *result) 
	EXPECT_EQ(0x80, result->bad_cb_test_rv, PRIu32);

	EXPECT_EQ(0, result->good_cb_test_rv, PRIu32);

	EXPECT_EQ(1, result->num_listen, PRIu32);

	EXPECT_EQ(EXPECTED_CLOSE_EVENTS, result->num_close_events, PRIu32);



	return 0;

err:

	return -1;

	return ret;

}



int verify_sockopt_result(int sock_map_fd)

{

	__u32 key = 0;

	int ret = 0;

	int res;

	int rv;
@@ -69,9 +73,7 @@ int verify_sockopt_result(int sock_map_fd) 
	rv = bpf_map_lookup_elem(sock_map_fd, &key, &res);

	EXPECT_EQ(0, rv, "d");

	EXPECT_EQ(1, res, "d");

	return 0;

err:

	return -1;

	return ret;

}



static int bpf_find_map(const char *test, struct bpf_object *obj,
@@ -96,6 +98,7 @@ int main(int argc, char **argv) 
	int error = EXIT_FAILURE;

	struct bpf_object *obj;

	int cg_fd = -1;

	int retry = 10;

	__u32 key = 0;

	int rv;
@@ -134,12 +137,20 @@ int main(int argc, char **argv) 
	if (sock_map_fd < 0)

		goto err;



retry_lookup:

	rv = bpf_map_lookup_elem(map_fd, &key, &g);

	if (rv != 0) {

		printf("FAILED: bpf_map_lookup_elem returns %d\n", rv);

		goto err;

	}



	if (g.num_close_events != EXPECTED_CLOSE_EVENTS && retry--) {

		printf("Unexpected number of close events (%d), retrying!\n",

		       g.num_close_events);

		usleep(100);

		goto retry_lookup;

	}



	if (verify_result(&g)) {

		printf("FAILED: Wrong stats\n");

		goto err;

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