The shared header to define SOCKMAP_MAX_ENTRIES is a bit overkill.

Dynamically allocate the sock_fd array based on bpf_map__max_entries
instead.

Suggested-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
---
 .../selftests/bpf/prog_tests/sockmap_basic.c  | 39 ++++++++++---------
 .../selftests/bpf/progs/bpf_iter_sockmap.c    |  5 +--
 .../selftests/bpf/progs/bpf_iter_sockmap.h    |  3 --
 3 files changed, 23 insertions(+), 24 deletions(-)
 delete mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_sockmap.h

Author: lmb

tools/testing/selftests/bpf/prog_tests/sockmap_basic.c

@@ -8,8 +8,6 @@
 #include "test_sockmap_invalid_update.skel.h"
 #include "bpf_iter_sockmap.skel.h"
 
-#include "progs/bpf_iter_sockmap.h"
-
 #define TCP_REPAIR		19	/* TCP sock is under repair right now */
 
 #define TCP_REPAIR_ON		1
@@ -179,9 +177,9 @@ static void test_sockmap_iter(enum bpf_map_type map_type)
 	DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);
 	int err, len, src_fd, iter_fd, duration = 0;
 	union bpf_iter_link_info linfo = {0};
-	__s64 sock_fd[SOCKMAP_MAX_ENTRIES];
-	__u32 i, num_sockets, max_elems;
+	__u32 i, num_sockets, num_elems;
 	struct bpf_iter_sockmap *skel;
+	__s64 *sock_fd = NULL;
 	struct bpf_link *link;
 	struct bpf_map *src;
 	char buf[64];
@@ -190,22 +188,26 @@ static void test_sockmap_iter(enum bpf_map_type map_type)
 	if (CHECK(!skel, "bpf_iter_sockmap__open_and_load", "skeleton open_and_load failed\n"))
 		return;
 
-	for (i = 0; i < ARRAY_SIZE(sock_fd); i++)
-		sock_fd[i] = -1;
-
-	/* Make sure we have at least one "empty" entry to test iteration of
-	 * an empty slot.
-	 */
-	num_sockets = ARRAY_SIZE(sock_fd) - 1;
-
 	if (map_type == BPF_MAP_TYPE_SOCKMAP) {
 		src = skel->maps.sockmap;
-		max_elems = bpf_map__max_entries(src);
+		num_elems = bpf_map__max_entries(src);
 	} else {
 		src = skel->maps.sockhash;
-		max_elems = num_sockets;
+		num_elems = bpf_map__max_entries(src) - 1;
 	}
 
+	/* Make sure we have at least one "empty" entry to test iteration of
+	 * an empty slot.
+	 */
+	num_sockets = bpf_map__max_entries(src) - 1;
+
+	sock_fd = calloc(num_sockets, sizeof(*sock_fd));
+	if (CHECK(!sock_fd, "calloc(sock_fd)", "failed to allocate\n"))
+		goto out;
+
+	for (i = 0; i < num_sockets; i++)
+		sock_fd[i] = -1;
+
 	src_fd = bpf_map__fd(src);
 
 	for (i = 0; i < num_sockets; i++) {
@@ -236,8 +238,8 @@ static void test_sockmap_iter(enum bpf_map_type map_type)
 		goto close_iter;
 
 	/* test results */
-	if (CHECK(skel->bss->elems != max_elems, "elems", "got %u expected %u\n",
-		  skel->bss->elems, max_elems))
+	if (CHECK(skel->bss->elems != num_elems, "elems", "got %u expected %u\n",
+		  skel->bss->elems, num_elems))
 		goto close_iter;
 
 	if (CHECK(skel->bss->socks != num_sockets, "socks", "got %u expected %u\n",
@@ -249,10 +251,11 @@ static void test_sockmap_iter(enum bpf_map_type map_type)
 free_link:
 	bpf_link__destroy(link);
 out:
-	for (i = 0; i < num_sockets; i++) {
+	for (i = 0; sock_fd && i < num_sockets; i++)
 		if (sock_fd[i] >= 0)
 			close(sock_fd[i]);
-	}
+	if (sock_fd)
+		free(sock_fd);
 	bpf_iter_sockmap__destroy(skel);
 }
 

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

@@ -2,7 +2,6 @@
 /* Copyright (c) 2020 Cloudflare */
 #include "bpf_iter.h"
 #include "bpf_tracing_net.h"
-#include "bpf_iter_sockmap.h"
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 #include <errno.h>
@@ -11,14 +10,14 @@ char _license[] SEC("license") = "GPL";
 
 struct {
 	__uint(type, BPF_MAP_TYPE_SOCKMAP);
-	__uint(max_entries, SOCKMAP_MAX_ENTRIES);
+	__uint(max_entries, 64);
 	__type(key, __u32);
 	__type(value, __u64);
 } sockmap SEC(".maps");
 
 struct {
 	__uint(type, BPF_MAP_TYPE_SOCKHASH);
-	__uint(max_entries, SOCKMAP_MAX_ENTRIES);
+	__uint(max_entries, 64);
 	__type(key, __u32);
 	__type(value, __u64);
 } sockhash SEC(".maps");