Merge branch 'bpf-btf-for-htab-lru'

Yonghong Song says:

====================
Commit a26ca7c982cb ("bpf: btf: Add pretty print support to
the basic arraymap") added pretty print support to array map.
This patch adds pretty print for hash and lru_hash maps.

The following example shows the pretty-print result of a pinned
hashmap. Without this patch set, user will get an error instead.

    struct map_value {
            int count_a;
            int count_b;
    };

    cat /sys/fs/bpf/pinned_hash_map:

    87907: {87907,87908}
    57354: {37354,57355}
    76625: {76625,76626}
    ...

Patch #1 fixed a bug in bpffs map_seq_next() function so that
all elements in the hash table will be traversed.
Patch #2 implemented map_seq_show_elem() and map_check_btf()
callback functions for hash and lru hash maps.
Patch #3 enhanced tools/testing/selftests/bpf/test_btf.c to
test bpffs hash and lru hash map pretty print.
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 5 insertions, 3 deletions

diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 76efe9a183f5..fc5b103512e7 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -196,19 +196,21 @@ static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos)
 {
 	struct bpf_map *map = seq_file_to_map(m);
 	void *key = map_iter(m)->key;
+	void *prev_key;
 
 	if (map_iter(m)->done)
 		return NULL;
 
 	if (unlikely(v == SEQ_START_TOKEN))
-		goto done;
+		prev_key = NULL;
+	else
+		prev_key = key;
 
-	if (map->ops->map_get_next_key(map, key, key)) {
+	if (map->ops->map_get_next_key(map, prev_key, key)) {
 		map_iter(m)->done = true;
 		return NULL;
 	}
 
-done:
 	++(*pos);
 	return key;
 }