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authorAlexei Starovoitov <ast@kernel.org>2020-06-29 21:33:39 -0700
committerAlexei Starovoitov <ast@kernel.org>2020-07-01 08:07:13 -0700
commitbba1dc0b55ac462d24ed1228ad49800c238cd6d7 (patch)
treed83554930260fe70393ea2d74734357577035dce /kernel/bpf/arraymap.c
parent8c18311067d0f0d5f332b9e1f3859eb15e23332d (diff)
bpf: Remove redundant synchronize_rcu.
bpf_free_used_maps() or close(map_fd) will trigger map_free callback. bpf_free_used_maps() is called after bpf prog is no longer executing: bpf_prog_put->call_rcu->bpf_prog_free->bpf_free_used_maps. Hence there is no need to call synchronize_rcu() to protect map elements. Note that hash_of_maps and array_of_maps update/delete inner maps via sys_bpf() that calls maybe_wait_bpf_programs() and synchronize_rcu(). Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Paul E. McKenney <paulmck@kernel.org> Link: https://lore.kernel.org/bpf/20200630043343.53195-2-alexei.starovoitov@gmail.com
Diffstat (limited to 'kernel/bpf/arraymap.c')
-rw-r--r--kernel/bpf/arraymap.c9
1 files changed, 0 insertions, 9 deletions
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index ec5cd11032aa..c66e8273fccd 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -386,13 +386,6 @@ static void array_map_free(struct bpf_map *map)
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
- /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
- * so the programs (can be more than one that used this map) were
- * disconnected from events. Wait for outstanding programs to complete
- * and free the array
- */
- synchronize_rcu();
-
if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
bpf_array_free_percpu(array);
@@ -546,8 +539,6 @@ static void fd_array_map_free(struct bpf_map *map)
struct bpf_array *array = container_of(map, struct bpf_array, map);
int i;
- synchronize_rcu();
-
/* make sure it's empty */
for (i = 0; i < array->map.max_entries; i++)
BUG_ON(array->ptrs[i] != NULL);