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Message-ID: <20200729040913.2815687-2-andriin@fb.com>
Date: Tue, 28 Jul 2020 21:09:13 -0700
From: Andrii Nakryiko <andriin@...com>
To: <bpf@...r.kernel.org>, <netdev@...r.kernel.org>, <ast@...com>,
<daniel@...earbox.net>
CC: <andrii.nakryiko@...il.com>, <kernel-team@...com>,
Andrii Nakryiko <andriin@...com>,
Song Liu <songliubraving@...com>, <stable@...r.kernel.org>
Subject: [PATCH v4 bpf 2/2] selftests/bpf: extend map-in-map selftest to detect memory leaks
Add test validating that all inner maps are released properly after skeleton
is destroyed. To ensure determinism, trigger kernel-side synchronize_rcu()
before checking map existence by their IDs.
Acked-by: Song Liu <songliubraving@...com>
Signed-off-by: Andrii Nakryiko <andriin@...com>
---
.../selftests/bpf/prog_tests/btf_map_in_map.c | 124 ++++++++++++++++--
1 file changed, 110 insertions(+), 14 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/btf_map_in_map.c b/tools/testing/selftests/bpf/prog_tests/btf_map_in_map.c
index f7ee8fa377ad..f6eee3fb933c 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf_map_in_map.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf_map_in_map.c
@@ -5,10 +5,60 @@
#include "test_btf_map_in_map.skel.h"
+static int duration;
+
+static __u32 bpf_map_id(struct bpf_map *map)
+{
+ struct bpf_map_info info;
+ __u32 info_len = sizeof(info);
+ int err;
+
+ memset(&info, 0, info_len);
+ err = bpf_obj_get_info_by_fd(bpf_map__fd(map), &info, &info_len);
+ if (err)
+ return 0;
+ return info.id;
+}
+
+/*
+ * Trigger synchronize_cpu() in kernel.
+ *
+ * ARRAY_OF_MAPS/HASH_OF_MAPS lookup/update operations trigger
+ * synchronize_rcu(), if looking up/updating non-NULL element. Use this fact
+ * to trigger synchronize_cpu(): create map-in-map, create a trivial ARRAY
+ * map, update map-in-map with ARRAY inner map. Then cleanup. At the end, at
+ * least one synchronize_rcu() would be called.
+ */
+static int kern_sync_rcu(void)
+{
+ int inner_map_fd, outer_map_fd, err, zero = 0;
+
+ inner_map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, 4, 4, 1, 0);
+ if (CHECK(inner_map_fd < 0, "inner_map_create", "failed %d\n", -errno))
+ return -1;
+
+ outer_map_fd = bpf_create_map_in_map(BPF_MAP_TYPE_ARRAY_OF_MAPS, NULL,
+ sizeof(int), inner_map_fd, 1, 0);
+ if (CHECK(outer_map_fd < 0, "outer_map_create", "failed %d\n", -errno)) {
+ close(inner_map_fd);
+ return -1;
+ }
+
+ err = bpf_map_update_elem(outer_map_fd, &zero, &inner_map_fd, 0);
+ if (err)
+ err = -errno;
+ CHECK(err, "outer_map_update", "failed %d\n", err);
+ close(inner_map_fd);
+ close(outer_map_fd);
+ return err;
+}
+
void test_btf_map_in_map(void)
{
- int duration = 0, err, key = 0, val;
- struct test_btf_map_in_map* skel;
+ int err, key = 0, val, i;
+ struct test_btf_map_in_map *skel;
+ int outer_arr_fd, outer_hash_fd;
+ int fd, map1_fd, map2_fd, map1_id, map2_id;
skel = test_btf_map_in_map__open_and_load();
if (CHECK(!skel, "skel_open", "failed to open&load skeleton\n"))
@@ -18,32 +68,78 @@ void test_btf_map_in_map(void)
if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
goto cleanup;
+ map1_fd = bpf_map__fd(skel->maps.inner_map1);
+ map2_fd = bpf_map__fd(skel->maps.inner_map2);
+ outer_arr_fd = bpf_map__fd(skel->maps.outer_arr);
+ outer_hash_fd = bpf_map__fd(skel->maps.outer_hash);
+
/* inner1 = input, inner2 = input + 1 */
- val = bpf_map__fd(skel->maps.inner_map1);
- bpf_map_update_elem(bpf_map__fd(skel->maps.outer_arr), &key, &val, 0);
- val = bpf_map__fd(skel->maps.inner_map2);
- bpf_map_update_elem(bpf_map__fd(skel->maps.outer_hash), &key, &val, 0);
+ map1_fd = bpf_map__fd(skel->maps.inner_map1);
+ bpf_map_update_elem(outer_arr_fd, &key, &map1_fd, 0);
+ map2_fd = bpf_map__fd(skel->maps.inner_map2);
+ bpf_map_update_elem(outer_hash_fd, &key, &map2_fd, 0);
skel->bss->input = 1;
usleep(1);
- bpf_map_lookup_elem(bpf_map__fd(skel->maps.inner_map1), &key, &val);
+ bpf_map_lookup_elem(map1_fd, &key, &val);
CHECK(val != 1, "inner1", "got %d != exp %d\n", val, 1);
- bpf_map_lookup_elem(bpf_map__fd(skel->maps.inner_map2), &key, &val);
+ bpf_map_lookup_elem(map2_fd, &key, &val);
CHECK(val != 2, "inner2", "got %d != exp %d\n", val, 2);
/* inner1 = input + 1, inner2 = input */
- val = bpf_map__fd(skel->maps.inner_map2);
- bpf_map_update_elem(bpf_map__fd(skel->maps.outer_arr), &key, &val, 0);
- val = bpf_map__fd(skel->maps.inner_map1);
- bpf_map_update_elem(bpf_map__fd(skel->maps.outer_hash), &key, &val, 0);
+ bpf_map_update_elem(outer_arr_fd, &key, &map2_fd, 0);
+ bpf_map_update_elem(outer_hash_fd, &key, &map1_fd, 0);
skel->bss->input = 3;
usleep(1);
- bpf_map_lookup_elem(bpf_map__fd(skel->maps.inner_map1), &key, &val);
+ bpf_map_lookup_elem(map1_fd, &key, &val);
CHECK(val != 4, "inner1", "got %d != exp %d\n", val, 4);
- bpf_map_lookup_elem(bpf_map__fd(skel->maps.inner_map2), &key, &val);
+ bpf_map_lookup_elem(map2_fd, &key, &val);
CHECK(val != 3, "inner2", "got %d != exp %d\n", val, 3);
+ for (i = 0; i < 5; i++) {
+ val = i % 2 ? map1_fd : map2_fd;
+ err = bpf_map_update_elem(outer_hash_fd, &key, &val, 0);
+ if (CHECK_FAIL(err)) {
+ printf("failed to update hash_of_maps on iter #%d\n", i);
+ goto cleanup;
+ }
+ err = bpf_map_update_elem(outer_arr_fd, &key, &val, 0);
+ if (CHECK_FAIL(err)) {
+ printf("failed to update hash_of_maps on iter #%d\n", i);
+ goto cleanup;
+ }
+ }
+
+ map1_id = bpf_map_id(skel->maps.inner_map1);
+ map2_id = bpf_map_id(skel->maps.inner_map2);
+ CHECK(map1_id == 0, "map1_id", "failed to get ID 1\n");
+ CHECK(map2_id == 0, "map2_id", "failed to get ID 2\n");
+
+ test_btf_map_in_map__destroy(skel);
+ skel = NULL;
+
+ /* we need to either wait for or force synchronize_rcu(), before
+ * checking for "still exists" condition, otherwise map could still be
+ * resolvable by ID, causing false positives.
+ *
+ * Older kernels (5.8 and earlier) freed map only after two
+ * synchronize_rcu()s, so trigger two, to be entirely sure.
+ */
+ CHECK(kern_sync_rcu(), "sync_rcu", "failed\n");
+ CHECK(kern_sync_rcu(), "sync_rcu", "failed\n");
+
+ fd = bpf_map_get_fd_by_id(map1_id);
+ if (CHECK(fd >= 0, "map1_leak", "inner_map1 leaked!\n")) {
+ close(fd);
+ goto cleanup;
+ }
+ fd = bpf_map_get_fd_by_id(map2_id);
+ if (CHECK(fd >= 0, "map2_leak", "inner_map2 leaked!\n")) {
+ close(fd);
+ goto cleanup;
+ }
+
cleanup:
test_btf_map_in_map__destroy(skel);
}
--
2.24.1
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