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authorMartin KaFai Lau <kafai@fb.com>2017-03-22 20:00:34 +0300
committerDavid S. Miller <davem@davemloft.net>2017-03-23 01:45:45 +0300
commitbcc6b1b7ebf857a9fe56202e2be3361131588c15 (patch)
treebc23c28ffe4866226ca8d768f67e74ddd9721076 /include/linux/bpf.h
parent56f668dfe00dcf086734f1c42ea999398fad6572 (diff)
downloadlinux-bcc6b1b7ebf857a9fe56202e2be3361131588c15.tar.xz
bpf: Add hash of maps support
This patch adds hash of maps support (hashmap->bpf_map). BPF_MAP_TYPE_HASH_OF_MAPS is added. A map-in-map contains a pointer to another map and lets call this pointer 'inner_map_ptr'. Notes on deleting inner_map_ptr from a hash map: 1. For BPF_F_NO_PREALLOC map-in-map, when deleting an inner_map_ptr, the htab_elem itself will go through a rcu grace period and the inner_map_ptr resides in the htab_elem. 2. For pre-allocated htab_elem (!BPF_F_NO_PREALLOC), when deleting an inner_map_ptr, the htab_elem may get reused immediately. This situation is similar to the existing prealloc-ated use cases. However, the bpf_map_fd_put_ptr() calls bpf_map_put() which calls inner_map->ops->map_free(inner_map) which will go through a rcu grace period (i.e. all bpf_map's map_free currently goes through a rcu grace period). Hence, the inner_map_ptr is still safe for the rcu reader side. This patch also includes BPF_MAP_TYPE_HASH_OF_MAPS to the check_map_prealloc() in the verifier. preallocation is a must for BPF_PROG_TYPE_PERF_EVENT. Hence, even we don't expect heavy updates to map-in-map, enforcing BPF_F_NO_PREALLOC for map-in-map is impossible without disallowing BPF_PROG_TYPE_PERF_EVENT from using map-in-map first. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Acked-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 'include/linux/bpf.h')
-rw-r--r--include/linux/bpf.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 3f3cdf9b15e8..2ae39a3e9ead 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -277,6 +277,8 @@ int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value);
int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
void *key, void *value, u64 map_flags);
void bpf_fd_array_map_clear(struct bpf_map *map);
+int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
+ void *key, void *value, u64 map_flags);
/* memcpy that is used with 8-byte aligned pointers, power-of-8 size and
* forced to use 'long' read/writes to try to atomically copy long counters.