On 1/15/24 6:50 AM, Hou Tao wrote:
Hi,
On 1/15/2024 8:59 PM, Andrey Grafin wrote:
This patch allows to create BPF_MAP_TYPE_ARRAY_OF_MAPS and
BPF_MAP_TYPE_HASH_OF_MAPS with values of BPF_MAP_TYPE_PERF_EVENT_ARRAY.
Previous behaviour created a zero filled btf_map_def for inner maps and
tried to use it for a map creation but the linux kernel forbids to create
a BPF_MAP_TYPE_PERF_EVENT_ARRAY map with max_entries=0.
Signed-off-by: Andrey Grafin <conquistador@xxxxxxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 4 +++
.../selftests/bpf/progs/test_map_in_map.c | 23 +++++++++++++++
tools/testing/selftests/bpf/test_maps.c | 29 ++++++++++++++++++-
It would be better to move the selftest into a separated patch, so the
fix patch for libbpf could be backported alone.
+1. Please put the selftest into the second patch.
Also for the second patch commit message, please mention
the test run result. For example, command line './test_maps',
without the first patch:
...
err ...
with the first patch:
...
... // everything is okay
3 files changed, 55 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e067be95da3c..8f4d580187aa 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -70,6 +70,7 @@
static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
+static int map_set_def_max_entries(struct bpf_map *map);
static const char * const attach_type_name[] = {
[BPF_CGROUP_INET_INGRESS] = "cgroup_inet_ingress",
@@ -5212,6 +5213,9 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
if (bpf_map_type__is_map_in_map(def->type)) {
if (map->inner_map) {
+ err = map_set_def_max_entries(map->inner_map);
+ if (err)
+ return err;
err = bpf_object__create_map(obj, map->inner_map, true);
if (err) {
pr_warn("map '%s': failed to create inner map: %d\n",
diff --git a/tools/testing/selftests/bpf/progs/test_map_in_map.c b/tools/testing/selftests/bpf/progs/test_map_in_map.c
index f416032ba858..b393d2b8bd6f 100644
--- a/tools/testing/selftests/bpf/progs/test_map_in_map.c
+++ b/tools/testing/selftests/bpf/progs/test_map_in_map.c
@@ -21,6 +21,29 @@ struct {
__type(value, __u32);
} mim_hash SEC(".maps");
+struct perf_event_array {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __type(key, __u32);
+ __type(value, __u32);
+} inner_map0 SEC(".maps"), inner_map1 SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
+ __uint(max_entries, 2);
+ __type(key, __u32);
+ __array(values, struct perf_event_array);
+} mim_array_pe SEC(".maps") = {
+ .values = {&inner_map0, &inner_map1}};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH_OF_MAPS);
+ __uint(max_entries, 2);
+ __type(key, __u32);
+ __array(values, struct perf_event_array);
+} mim_hash_pe SEC(".maps") = {
+ .values = {&inner_map0, &inner_map1}};
This is tricky. I suggest to have max_entries to be
1 for BPF_MAP_TYPE_HASH_OF_MAPS and put only &inner_map0
in 'values'. If you have two buckets for the
hash table, actually it is not clear eventually
which map in which bucket.
+
+
SEC("xdp")
int xdp_mimtest0(struct xdp_md *ctx)
{
diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
index 7fc00e423e4d..03f4d448fd3b 100644
--- a/tools/testing/selftests/bpf/test_maps.c
+++ b/tools/testing/selftests/bpf/test_maps.c
@@ -1159,6 +1159,7 @@ static void test_map_in_map(void)
__u32 len = sizeof(info);
__u32 id = 0;
libbpf_print_fn_t old_print_fn;
+ int ret;
Why not use err instead ?
obj = bpf_object__open(MAPINMAP_PROG);
@@ -1190,7 +1191,11 @@ static void test_map_in_map(void)
goto out_map_in_map;
}
- bpf_object__load(obj);
+ ret = bpf_object__load(obj);
+ if (ret) {
+ printf("Failed to load test prog\n");
+ goto out_map_in_map;
+ }
map = bpf_object__find_map_by_name(obj, "mim_array");
if (!map) {
@@ -1226,6 +1231,28 @@ static void test_map_in_map(void)
goto out_map_in_map;
}
+ map = bpf_object__find_map_by_name(obj, "mim_array_pe");
+ if (!map) {
+ printf("Failed to load array of perf event array maps\n");
+ goto out_map_in_map;
+ }
+ mim_fd = bpf_map__fd(map);
+ if (mim_fd < 0) {
+ printf("Failed to get descriptor for array of perf event array maps\n");
+ goto out_map_in_map;
+ }
+
+ map = bpf_object__find_map_by_name(obj, "mim_hash_pe");
+ if (!map) {
+ printf("Failed to load hash of perf event array maps\n");
+ goto out_map_in_map;
+ }
+ mim_fd = bpf_map__fd(map);
+ if (mim_fd < 0) {
+ printf("Failed to get descriptor for array of perf event array maps\n");
array -> hash ?
+ goto out_map_in_map;
+ }
The above change is really not necessary. If program loading is successful, all the
maps should be created properly. I think your above bpf_object__load test should be
good enough.
+
close(fd);
fd = -1;
bpf_object__close(obj);
