On 6/30/20 8:15 AM, Andrii Nakryiko wrote:
BPF ringbuf assumes the size to be a multiple of page size and the power of
2 value. The latter is important to avoid division while calculating position
inside the ring buffer and using (N-1) mask instead. This patch fixes omission
to enforce power-of-2 size rule.
Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it")
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
Lgtm, applied, thanks!
[...]
@@ -166,9 +157,16 @@ static struct bpf_map *ringbuf_map_alloc(union bpf_attr *attr)
return ERR_PTR(-EINVAL);
if (attr->key_size || attr->value_size ||
- attr->max_entries == 0 || !PAGE_ALIGNED(attr->max_entries))
+ !is_power_of_2(attr->max_entries) ||
+ !PAGE_ALIGNED(attr->max_entries))
Technically !IS_ALIGNED(attr->max_entries, PAGE_SIZE) might have been a bit cleaner
since PAGE_ALIGNED() is only intended for pointers, though, not wrong here given
max_entries is u32.
Thanks,
Daniel
