From bba1dc0b55ac462d24ed1228ad49800c238cd6d7 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 29 Jun 2020 21:33:39 -0700 Subject: 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 Acked-by: Andrii Nakryiko Acked-by: Paul E. McKenney Link: https://lore.kernel.org/bpf/20200630043343.53195-2-alexei.starovoitov@gmail.com --- kernel/bpf/arraymap.c | 9 --------- 1 file changed, 9 deletions(-) (limited to 'kernel/bpf/arraymap.c') 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); -- cgit v1.2.3-59-g8ed1b