4 files changed, 133 insertions, 8 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index b2509cd0b930..bb2b751d274a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -608,11 +608,19 @@ 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 */
-	void *		destructor_arg;
+	union {
+		struct {
+			u32		xdp_frags_size;
+			u32		xdp_frags_truesize;
+		};
+
+		/*
+		 * Intermediate layers must ensure that destructor_arg
+		 * remains valid until skb destructor.
+		 */
+		void		*destructor_arg;
+	};
 
 	/* must be last field, see pskb_expand_head() */
 	skb_frag_t	frags[MAX_SKB_FRAGS];
diff --git a/include/net/page_pool/helpers.h b/include/net/page_pool/helpers.h
index 776a3008ac28..543f54fa3020 100644
--- a/include/net/page_pool/helpers.h
+++ b/include/net/page_pool/helpers.h
@@ -144,6 +144,15 @@ static inline netmem_ref page_pool_alloc_netmem(struct page_pool *pool,
 	return netmem;
 }
 
+static inline netmem_ref page_pool_dev_alloc_netmem(struct page_pool *pool,
+						    unsigned int *offset,
+						    unsigned int *size)
+{
+	gfp_t gfp = GFP_ATOMIC | __GFP_NOWARN;
+
+	return page_pool_alloc_netmem(pool, offset, size, gfp);
+}
+
 static inline struct page *page_pool_alloc(struct page_pool *pool,
 					   unsigned int *offset,
 					   unsigned int *size, gfp_t gfp)
diff --git a/include/net/xdp.h b/include/net/xdp.h
index d2089cfecefd..6da0e746cf75 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -167,6 +167,93 @@ out:
 	return len;
 }
 
+void xdp_return_frag(netmem_ref netmem, const struct xdp_buff *xdp);
+
+/**
+ * __xdp_buff_add_frag - attach frag to &xdp_buff
+ * @xdp: XDP buffer to attach the frag to
+ * @netmem: network memory containing the frag
+ * @offset: offset at which the frag starts
+ * @size: size of the frag
+ * @truesize: total memory size occupied by the frag
+ * @try_coalesce: whether to try coalescing the frags (not valid for XSk)
+ *
+ * Attach frag to the XDP buffer. If it currently has no frags attached,
+ * initialize the related fields, otherwise check that the frag number
+ * didn't reach the limit of ``MAX_SKB_FRAGS``. If possible, try coalescing
+ * the frag with the previous one.
+ * The function doesn't check/update the pfmemalloc bit. Please use the
+ * non-underscored wrapper in drivers.
+ *
+ * Return: true on success, false if there's no space for the frag in
+ * the shared info struct.
+ */
+static inline bool __xdp_buff_add_frag(struct xdp_buff *xdp, netmem_ref netmem,
+				       u32 offset, u32 size, u32 truesize,
+				       bool try_coalesce)
+{
+	struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
+	skb_frag_t *prev;
+	u32 nr_frags;
+
+	if (!xdp_buff_has_frags(xdp)) {
+		xdp_buff_set_frags_flag(xdp);
+
+		nr_frags = 0;
+		sinfo->xdp_frags_size = 0;
+		sinfo->xdp_frags_truesize = 0;
+
+		goto fill;
+	}
+
+	nr_frags = sinfo->nr_frags;
+	prev = &sinfo->frags[nr_frags - 1];
+
+	if (try_coalesce && netmem == skb_frag_netmem(prev) &&
+	    offset == skb_frag_off(prev) + skb_frag_size(prev)) {
+		skb_frag_size_add(prev, size);
+		/* Guaranteed to only decrement the refcount */
+		xdp_return_frag(netmem, xdp);
+	} else if (unlikely(nr_frags == MAX_SKB_FRAGS)) {
+		return false;
+	} else {
+fill:
+		__skb_fill_netmem_desc_noacc(sinfo, nr_frags++, netmem,
+					     offset, size);
+	}
+
+	sinfo->nr_frags = nr_frags;
+	sinfo->xdp_frags_size += size;
+	sinfo->xdp_frags_truesize += truesize;
+
+	return true;
+}
+
+/**
+ * xdp_buff_add_frag - attach frag to &xdp_buff
+ * @xdp: XDP buffer to attach the frag to
+ * @netmem: network memory containing the frag
+ * @offset: offset at which the frag starts
+ * @size: size of the frag
+ * @truesize: total memory size occupied by the frag
+ *
+ * Version of __xdp_buff_add_frag() which takes care of the pfmemalloc bit.
+ *
+ * Return: true on success, false if there's no space for the frag in
+ * the shared info struct.
+ */
+static inline bool xdp_buff_add_frag(struct xdp_buff *xdp, netmem_ref netmem,
+				     u32 offset, u32 size, u32 truesize)
+{
+	if (!__xdp_buff_add_frag(xdp, netmem, offset, size, truesize, true))
+		return false;
+
+	if (unlikely(netmem_is_pfmemalloc(netmem)))
+		xdp_buff_set_frag_pfmemalloc(xdp);
+
+	return true;
+}
+
 struct xdp_frame {
 	void *data;
 	u32 len;
@@ -230,7 +317,14 @@ xdp_update_skb_shared_info(struct sk_buff *skb, u8 nr_frags,
 			   unsigned int size, unsigned int truesize,
 			   bool pfmemalloc)
 {
-	skb_shinfo(skb)->nr_frags = nr_frags;
+	struct skb_shared_info *sinfo = skb_shinfo(skb);
+
+	sinfo->nr_frags = nr_frags;
+	/*
+	 * ``destructor_arg`` is unionized with ``xdp_frags_{,true}size``,
+	 * reset it after that these fields aren't used anymore.
+	 */
+	sinfo->destructor_arg = NULL;
 
 	skb->len += size;
 	skb->data_len += size;
@@ -242,6 +336,8 @@ 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(const struct xdp_buff *xdp);
+struct sk_buff *xdp_build_skb_from_zc(struct xdp_buff *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/include/net/xdp_sock_drv.h b/include/net/xdp_sock_drv.h
index f3175a5d28f7..86620c818965 100644
--- a/include/net/xdp_sock_drv.h
+++ b/include/net/xdp_sock_drv.h
@@ -136,11 +136,21 @@ out:
 	xp_free(xskb);
 }
 
-static inline void xsk_buff_add_frag(struct xdp_buff *xdp)
+static inline bool xsk_buff_add_frag(struct xdp_buff *head,
+				     struct xdp_buff *xdp)
 {
-	struct xdp_buff_xsk *frag = container_of(xdp, struct xdp_buff_xsk, xdp);
+	const void *data = xdp->data;
+	struct xdp_buff_xsk *frag;
+
+	if (!__xdp_buff_add_frag(head, virt_to_netmem(data),
+				 offset_in_page(data), xdp->data_end - data,
+				 xdp->frame_sz, false))
+		return false;
 
+	frag = container_of(xdp, struct xdp_buff_xsk, xdp);
 	list_add_tail(&frag->list_node, &frag->pool->xskb_list);
+
+	return true;
 }
 
 static inline struct xdp_buff *xsk_buff_get_frag(const struct xdp_buff *first)
@@ -357,8 +367,10 @@ static inline void xsk_buff_free(struct xdp_buff *xdp)
 {
 }
 
-static inline void xsk_buff_add_frag(struct xdp_buff *xdp)
+static inline bool xsk_buff_add_frag(struct xdp_buff *head,
+				     struct xdp_buff *xdp)
 {
+	return false;
 }
 
 static inline struct xdp_buff *xsk_buff_get_frag(const struct xdp_buff *first)