On Wed, Dec 20, 2023 at 01:45:02PM -0800, Mina Almasry wrote:
> Use netmem_ref instead of page in skb_frag_t. Currently netmem_ref
> is always a struct page underneath, but the abstraction allows efforts
> to add support for skb frags not backed by pages.
>
> There is unfortunately 1 instance where the skb_frag_t is assumed to be
> a bio_vec in kcm. For this case, add a debug assert that the skb frag is
> indeed backed by a page, and do a cast.
>
> Add skb[_frag]_fill_netmem_*() and skb_add_rx_frag_netmem() helpers so
> that the API can be used to create netmem skbs.
>
> Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx>
...
> diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
> index 65d1f6755f98..3180a54b2c68 100644
> --- a/net/kcm/kcmsock.c
> +++ b/net/kcm/kcmsock.c
> @@ -636,9 +636,15 @@ static int kcm_write_msgs(struct kcm_sock *kcm)
> for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
> msize += skb_shinfo(skb)->frags[i].bv_len;
>
> + /* The cast to struct bio_vec* here assumes the frags are
> + * struct page based. WARN if there is no page in this skb.
> + */
> + DEBUG_NET_WARN_ON_ONCE(
> + !skb_frag_page(&skb_shinfo(skb)->frags[0]));
> +
> iov_iter_bvec(&msg.msg_iter, ITER_SOURCE,
> - skb_shinfo(skb)->frags, skb_shinfo(skb)->nr_frags,
> - msize);
> + (const struct bio_vec *)skb_shinfo(skb)->frags,
> + skb_shinfo(skb)->nr_frags, msize);
> iov_iter_advance(&msg.msg_iter, txm->frag_offset);
>
> do {
Hi Mina,
something isn't quite right here.
...//kcmsock.c:637:39: error: no member named 'bv_len' in 'struct skb_frag'
637 | msize += skb_shinfo(skb)->frags[i].bv_len;
| ~~~~~~~~~~~~~~~~~~~~~~~~~ ^
--
pw-bot: changes-requested
