samples/bpf: load_bpf.c make callback fixup more flexible

Do this change before others start to use this callback.
Change map_perf_test_user.c which seems to be the only user.

This patch extends capabilities of commit 9fd63d05f3e8 ("bpf:
Allow bpf sample programs (*_user.c) to change bpf_map_def").

Give fixup callback access to struct bpf_map_data, instead of
only stuct bpf_map_def.  This add flexibility to allow userspace
to reassign the map file descriptor.  This is very useful when
wanting to share maps between several bpf programs.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 23 insertions, 18 deletions

diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
index fedec29c7817..74456b3eb89a 100644
--- a/samples/bpf/bpf_load.c
+++ b/samples/bpf/bpf_load.c
@@ -39,13 +39,6 @@ int event_fd[MAX_PROGS];
 int prog_cnt;
 int prog_array_fd = -1;
 
-/* Keeping relevant info on maps */
-struct bpf_map_data {
-        int fd;
-        char *name;
-        size_t elf_offset;
-        struct bpf_map_def def;
-};
 struct bpf_map_data map_data[MAX_MAPS];
 int map_data_count = 0;
 
@@ -202,8 +195,14 @@ static int load_maps(struct bpf_map_data *maps, int nr_maps,
         int i;
 
         for (i = 0; i < nr_maps; i++) {
-                if (fixup_map)
-                        fixup_map(&maps[i].def, maps[i].name, i);
+                if (fixup_map) {
+                        fixup_map(&maps[i], i);
+                        /* Allow userspace to assign map FD prior to creation */
+                        if (maps[i].fd != -1) {
+                                map_fd[i] = maps[i].fd;
+                                continue;
+                        }
+                }
 
                 if (maps[i].def.type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
                     maps[i].def.type == BPF_MAP_TYPE_HASH_OF_MAPS) {
diff --git a/samples/bpf/bpf_load.h b/samples/bpf/bpf_load.h
index 05822f83173a..4d4fd4678a64 100644
--- a/samples/bpf/bpf_load.h
+++ b/samples/bpf/bpf_load.h
@@ -15,8 +15,14 @@ struct bpf_map_def {
         unsigned int inner_map_idx;
 };
 
-typedef void (*fixup_map_cb)(struct bpf_map_def *map, const char *map_name,
-                             int idx);
+struct bpf_map_data {
+        int fd;
+        char *name;
+        size_t elf_offset;
+        struct bpf_map_def def;
+};
+
+typedef void (*fixup_map_cb)(struct bpf_map_data *map, int idx);
 
 extern int map_fd[MAX_MAPS];
 extern int prog_fd[MAX_PROGS];
diff --git a/samples/bpf/map_perf_test_user.c b/samples/bpf/map_perf_test_user.c
index 6ac778153315..1a8894b5ac51 100644
--- a/samples/bpf/map_perf_test_user.c
+++ b/samples/bpf/map_perf_test_user.c
@@ -320,21 +320,21 @@ static void fill_lpm_trie(void)
         assert(!r);
 }
 
-static void fixup_map(struct bpf_map_def *map, const char *name, int idx)
+static void fixup_map(struct bpf_map_data *map, int idx)
 {
         int i;
 
-        if (!strcmp("inner_lru_hash_map", name)) {
+        if (!strcmp("inner_lru_hash_map", map->name)) {
                 inner_lru_hash_idx = idx;
-                inner_lru_hash_size = map->max_entries;
+                inner_lru_hash_size = map->def.max_entries;
         }
 
-        if (!strcmp("array_of_lru_hashs", name)) {
+        if (!strcmp("array_of_lru_hashs", map->name)) {
                 if (inner_lru_hash_idx == -1) {
                         printf("inner_lru_hash_map must be defined before array_of_lru_hashs\n");
                         exit(1);
                 }
-                map->inner_map_idx = inner_lru_hash_idx;
+                map->def.inner_map_idx = inner_lru_hash_idx;
                 array_of_lru_hashs_idx = idx;
         }
 
@@ -345,9 +345,9 @@ static void fixup_map(struct bpf_map_def *map, const char *name, int idx)
 
         /* Only change the max_entries for the enabled test(s) */
         for (i = 0; i < NR_TESTS; i++) {
-                if (!strcmp(test_map_names[i], name) &&
+                if (!strcmp(test_map_names[i], map->name) &&
                     (check_test_flags(i))) {
-                        map->max_entries = num_map_entries;
+                        map->def.max_entries = num_map_entries;
                 }
         }
 }