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| author | Teng Qin <qinteng@fb.com> | 2017-04-24 19:00:37 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-04-25 11:57:45 -0400 |
| commit | 8fe45924387be6b5c1be59a7eb330790c61d5d10 (patch) | |
| tree | 1879f4fd4d14907155b1ebb2fd85ff26aa89ebbe /kernel/bpf/hashtab.c | |
| parent | 472ecf084a7687347f79720c83881c07407bfd8b (diff) | |
| download | linux-8fe45924387be6b5c1be59a7eb330790c61d5d10.tar.gz | |
bpf: map_get_next_key to return first key on NULL
When iterating through a map, we need to find a key that does not exist in the map so map_get_next_key will give us the first key of the map. This often requires a lot of guessing in production systems. This patch makes map_get_next_key return the first key when the key pointer in the parameter is NULL. Signed-off-by: Teng Qin <qinteng@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf/hashtab.c')
| -rw-r--r-- | kernel/bpf/hashtab.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index bc80c038e430..004334ea13ba 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -540,12 +540,15 @@ static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key) struct hlist_nulls_head *head; struct htab_elem *l, *next_l; u32 hash, key_size; - int i; + int i = 0; WARN_ON_ONCE(!rcu_read_lock_held()); key_size = map->key_size; + if (!key) + goto find_first_elem; + hash = htab_map_hash(key, key_size); head = select_bucket(htab, hash); @@ -553,10 +556,8 @@ static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key) /* lookup the key */ l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets); - if (!l) { - i = 0; + if (!l) goto find_first_elem; - } /* key was found, get next key in the same bucket */ next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_next_rcu(&l->hash_node)), |