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Date: Sat, 23 Dec 2023 03:55:33 +0100
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: Alexander Lobakin <aleksander.lobakin@...el.com>,
Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
Michal Kubiak <michal.kubiak@...el.com>,
Larysa Zaremba <larysa.zaremba@...el.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Willem de Bruijn <willemdebruijn.kernel@...il.com>,
intel-wired-lan@...ts.osuosl.org,
netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH RFC net-next 13/34] xdp: add generic xdp_build_skb_from_buff()
The code which builds an skb from an &xdp_buff keeps multiplying itself
around the drivers with almost no changes. Let's try to stop that by
adding a generic function.
There's __xdp_build_skb_from_frame() already, so just convert it to take
&xdp_buff instead, while making the original one a wrapper. The original
one always took an already allocated skb, allow both variants here -- if
no skb passed, which is expected when calling from a driver, pick one via
napi_build_skb().
Signed-off-by: Alexander Lobakin <aleksander.lobakin@...el.com>
---
include/net/xdp.h | 4 +++
net/core/xdp.c | 89 +++++++++++++++++++++++++++++++----------------
2 files changed, 63 insertions(+), 30 deletions(-)
diff --git a/include/net/xdp.h b/include/net/xdp.h
index a3dc0f39b437..4fcf0ac48345 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -276,6 +276,10 @@ xdp_update_skb_shared_info(struct sk_buff *skb, u8 nr_frags,
void xdp_warn(const char *msg, const char *func, const int line);
#define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__)
+struct sk_buff *__xdp_build_skb_from_buff(struct sk_buff *skb,
+ const struct xdp_buff *xdp);
+#define xdp_build_skb_from_buff(xdp) __xdp_build_skb_from_buff(NULL, xdp)
+
struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
struct sk_buff *skb,
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 03ebdb21ea62..ed73b97472b4 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -609,45 +609,77 @@ int xdp_alloc_skb_bulk(void **skbs, int n_skb, gfp_t gfp)
}
EXPORT_SYMBOL_GPL(xdp_alloc_skb_bulk);
-struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
- struct sk_buff *skb,
- struct net_device *dev)
+struct sk_buff *__xdp_build_skb_from_buff(struct sk_buff *skb,
+ const struct xdp_buff *xdp)
{
- struct skb_shared_info *sinfo = xdp_get_shared_info_from_frame(xdpf);
- unsigned int headroom, frame_size;
- void *hard_start;
- u8 nr_frags;
+ const struct xdp_rxq_info *rxq = xdp->rxq;
+ const struct skb_shared_info *sinfo;
+ u32 nr_frags = 0;
/* xdp frags frame */
- if (unlikely(xdp_frame_has_frags(xdpf)))
+ if (unlikely(xdp_buff_has_frags(xdp))) {
+ sinfo = xdp_get_shared_info_from_buff(xdp);
nr_frags = sinfo->nr_frags;
+ }
- /* Part of headroom was reserved to xdpf */
- headroom = sizeof(*xdpf) + xdpf->headroom;
+ net_prefetch(xdp->data_meta);
- /* Memory size backing xdp_frame data already have reserved
- * room for build_skb to place skb_shared_info in tailroom.
- */
- frame_size = xdpf->frame_sz;
+ if (!skb) {
+ skb = napi_build_skb(xdp->data_hard_start, xdp->frame_sz);
+ if (unlikely(!skb))
+ return NULL;
+ } else {
+ /* build_skb_around() can return NULL only when !skb, which
+ * is impossible here.
+ */
+ build_skb_around(skb, xdp->data_hard_start, xdp->frame_sz);
+ }
- hard_start = xdpf->data - headroom;
- skb = build_skb_around(skb, hard_start, frame_size);
- if (unlikely(!skb))
- return NULL;
+ skb_reserve(skb, xdp->data - xdp->data_hard_start);
+ __skb_put(skb, xdp->data_end - xdp->data);
+ if (xdp->data > xdp->data_meta)
+ skb_metadata_set(skb, xdp->data - xdp->data_meta);
+
+ if (rxq->mem.type == MEM_TYPE_PAGE_POOL)
+ skb_mark_for_recycle(skb);
- skb_reserve(skb, headroom);
- __skb_put(skb, xdpf->len);
- if (xdpf->metasize)
- skb_metadata_set(skb, xdpf->metasize);
+ /* __xdp_rxq_info_reg() sets these two together */
+ if (rxq->reg_state == REG_STATE_REGISTERED)
+ skb_record_rx_queue(skb, rxq->queue_index);
+
+ if (unlikely(nr_frags)) {
+ u32 truesize = sinfo->xdp_frags_truesize ? :
+ nr_frags * xdp->frame_sz;
- if (unlikely(xdp_frame_has_frags(xdpf)))
xdp_update_skb_shared_info(skb, nr_frags,
- sinfo->xdp_frags_size,
- nr_frags * xdpf->frame_sz,
- xdp_frame_is_frag_pfmemalloc(xdpf));
+ sinfo->xdp_frags_size, truesize,
+ xdp_buff_is_frag_pfmemalloc(xdp));
+ }
/* Essential SKB info: protocol and skb->dev */
- skb->protocol = eth_type_trans(skb, dev);
+ skb->protocol = eth_type_trans(skb, rxq->dev);
+
+ return skb;
+}
+EXPORT_SYMBOL_GPL(__xdp_build_skb_from_buff);
+
+struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
+ struct sk_buff *skb,
+ struct net_device *dev)
+{
+ struct xdp_rxq_info rxq = {
+ .dev = dev,
+ .mem = xdpf->mem,
+ };
+ struct xdp_buff xdp;
+
+ /* Check early instead of delegating it to build_skb_around() */
+ if (unlikely(!skb))
+ return NULL;
+
+ xdp.rxq = &rxq;
+ xdp_convert_frame_to_buff(xdpf, &xdp);
+ __xdp_build_skb_from_buff(skb, &xdp);
/* Optional SKB info, currently missing:
* - HW checksum info (skb->ip_summed)
@@ -655,9 +687,6 @@ struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
* - RX ring dev queue index (skb_record_rx_queue)
*/
- if (xdpf->mem.type == MEM_TYPE_PAGE_POOL)
- skb_mark_for_recycle(skb);
-
/* Allow SKB to reuse area used by xdp_frame */
xdp_scrub_frame(xdpf);
--
2.43.0
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