Magnus Karlsson wrote:
> When the need_wakeup flag was added to AF_XDP, the format of the
> XDP_MMAP_OFFSETS getsockopt was extended. Code was added to the kernel
> to take care of compatibility issues arrising from running
> applications using any of the two formats. However, libbpf was not
> extended to take care of the case when the application/libbpf uses the
> new format but the kernel only supports the old format. This patch
> adds support in libbpf for parsing the old format, before the
> need_wakeup flag was added, and emulating a set of static need_wakeup
> flags that will always work for the application.
>
> Fixes: a4500432c2587cb2a ("libbpf: add support for need_wakeup flag in AF_XDP part")
> Reported-by: Eloy Degen <degeneloy@xxxxxxxxx>
> Signed-off-by: Magnus Karlsson <magnus.karlsson@xxxxxxxxx>
> ---
> tools/lib/bpf/xsk.c | 109 +++++++++++++++++++++++++++++++++++++---------------
> 1 file changed, 78 insertions(+), 31 deletions(-)
>
> diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
> index a902838..46f9687 100644
> --- a/tools/lib/bpf/xsk.c
> +++ b/tools/lib/bpf/xsk.c
> @@ -44,6 +44,25 @@
> #define PF_XDP AF_XDP
> #endif
>
> +#define is_mmap_offsets_v1(optlen) \
> + ((optlen) == sizeof(struct xdp_mmap_offsets_v1))
> +
> +#define get_prod_off(ring) \
> + (is_mmap_offsets_v1(optlen) ? \
> + ((struct xdp_mmap_offsets_v1 *)&off)->ring.producer : \
> + off.ring.producer)
> +#define get_cons_off(ring) \
> + (is_mmap_offsets_v1(optlen) ? \
> + ((struct xdp_mmap_offsets_v1 *)&off)->ring.consumer : \
> + off.ring.consumer)
> +#define get_desc_off(ring) \
> + (is_mmap_offsets_v1(optlen) ? \
> + ((struct xdp_mmap_offsets_v1 *)&off)->ring.desc : off.ring.desc)
> +#define get_flags_off(ring) \
> + (is_mmap_offsets_v1(optlen) ? \
> + ((struct xdp_mmap_offsets_v1 *)&off)->ring.consumer + sizeof(u32) : \
> + off.ring.flags)
> +
It seems the only thing added was flags right? If so seems we
only need the last one there, get_flags_off(). I think it would
be a bit cleaner to just use the macros where its actually
needed IMO.
Thanks,
John
