diff options
| author | Hou Tao <houtao1@huawei.com> | 2023-12-14 05:30:09 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-12-14 05:49:11 +0100 |
| commit | 8f82583f9527b3be9d70d9a5d1f33435e29d0480 (patch) | |
| tree | f295c8b23b7beead0a0bb9a2e880b7356299769d /kernel/bpf | |
| parent | bpf: Update the comments in maybe_wait_bpf_programs() (diff) | |
| download | linux-8f82583f9527b3be9d70d9a5d1f33435e29d0480.tar.xz linux-8f82583f9527b3be9d70d9a5d1f33435e29d0480.zip | |
bpf: Reduce the scope of rcu_read_lock when updating fd map
There is no rcu-read-lock requirement for ops->map_fd_get_ptr() or
ops->map_fd_put_ptr(), so doesn't use rcu-read-lock for these two
callbacks.
For bpf_fd_array_map_update_elem(), accessing array->ptrs doesn't need
rcu-read-lock because array->ptrs must still be allocated. For
bpf_fd_htab_map_update_elem(), htab_map_update_elem() only requires
rcu-read-lock to be held to avoid the WARN_ON_ONCE(), so only use
rcu_read_lock() during the invocation of htab_map_update_elem().
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231214043010.3458072-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/hashtab.c | 6 | ||||
| -rw-r--r-- | kernel/bpf/syscall.c | 4 |
2 files changed, 6 insertions, 4 deletions
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 5b9146fa825f..ec3bdcc6a3cf 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -2523,7 +2523,13 @@ int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file, if (IS_ERR(ptr)) return PTR_ERR(ptr); + /* The htab bucket lock is always held during update operations in fd + * htab map, and the following rcu_read_lock() is only used to avoid + * the WARN_ON_ONCE in htab_map_update_elem(). + */ + rcu_read_lock(); ret = htab_map_update_elem(map, key, &ptr, map_flags); + rcu_read_unlock(); if (ret) map->ops->map_fd_put_ptr(map, ptr, false); diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index d63c1ed42412..3fcf7741146a 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -184,15 +184,11 @@ static int bpf_map_update_value(struct bpf_map *map, struct file *map_file, err = bpf_percpu_cgroup_storage_update(map, key, value, flags); } else if (IS_FD_ARRAY(map)) { - rcu_read_lock(); err = bpf_fd_array_map_update_elem(map, map_file, key, value, flags); - rcu_read_unlock(); } else if (map->map_type == BPF_MAP_TYPE_HASH_OF_MAPS) { - rcu_read_lock(); err = bpf_fd_htab_map_update_elem(map, map_file, key, value, flags); - rcu_read_unlock(); } else if (map->map_type == BPF_MAP_TYPE_REUSEPORT_SOCKARRAY) { /* rcu_read_lock() is not needed */ err = bpf_fd_reuseport_array_update_elem(map, key, value, |