diff options
| author | Alexei Starovoitov <ast@kernel.org> | 2020-06-29 21:33:39 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-07-01 08:07:13 -0700 |
| commit | bba1dc0b55ac462d24ed1228ad49800c238cd6d7 (patch) | |
| tree | d83554930260fe70393ea2d74734357577035dce /kernel/bpf/hashtab.c | |
| parent | 8c18311067d0f0d5f332b9e1f3859eb15e23332d (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/hashtab.c')
| -rw-r--r-- | kernel/bpf/hashtab.c | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index acd06081d81d..d4378d7d442b 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -1290,12 +1290,10 @@ static void htab_map_free(struct bpf_map *map) { struct bpf_htab *htab = container_of(map, struct bpf_htab, 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 critical sections in - * these programs to complete + /* bpf_free_used_maps() or close(map_fd) will trigger this map_free callback. + * bpf_free_used_maps() is called after bpf prog is no longer executing. + * There is no need to synchronize_rcu() here to protect map elements. */ - synchronize_rcu(); /* some of free_htab_elem() callbacks for elements of this map may * not have executed. Wait for them. |