Commit 509db283 authored Oct 09, 2018 by Prashant Bhole Committed by Alexei Starovoitov Oct 09, 2018

bpf: error handling when map_lookup_elem isn't supported



The error value returned by map_lookup_elem doesn't differentiate
whether lookup was failed because of invalid key or lookup is not
supported.

Lets add handling for -EOPNOTSUPP return value of map_lookup_elem()
method of map, with expectation from map's implementation that it
should return -EOPNOTSUPP if lookup is not supported.

The errno for bpf syscall for BPF_MAP_LOOKUP_ELEM command will be set
to EOPNOTSUPP if map lookup is not supported.

Signed-off-by: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent 8af03d1a

kernel/bpf/syscall.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -719,10 +719,15 @@ static int map_lookup_elem(union bpf_attr *attr)
		} else {
		rcu_read_lock();
		ptr = map->ops->map_lookup_elem(map, key);
		if (ptr)
		if (IS_ERR(ptr)) {
		err = PTR_ERR(ptr);
		} else if (!ptr) {
		err = -ENOENT;
		} else {
		err = 0;
		memcpy(value, ptr, value_size);
		}
		rcu_read_unlock();
		err = ptr ? 0 : -ENOENT;
		}

		if (err)