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>

1 files changed, 8 insertions, 9 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) {