net: skbuff: add size metadata to skb_shared_info for xdp

Introduce xdp_frags_size field in skb_shared_info data structure
to store xdp_buff/xdp_frame frame paged size (xdp_frags_size will
be used in xdp frags support). In order to not increase
skb_shared_info size we will use a hole due to skb_shared_info
alignment.

Acked-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/8a849819a3e0a143d540f78a3a5add76e17e980d.1642758637.git.lorenzo@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index bf11e1f..8131d0d 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -557,6 +557,7 @@ struct skb_shared_info {
         * Warning : all fields before dataref are cleared in __alloc_skb()
         */
        atomic_t        dataref;
+       unsigned int    xdp_frags_size;
 
        /* Intermediate layers must ensure that destructor_arg
         * remains valid until skb destructor */