[PATCH v14 bpf-next 02/18] xdp: introduce flags field in xdp_buff/xdp_frame

From: Lorenzo Bianconi <lorenzo@kernel.org>
To: bpf@vger.kernel.org, netdev@vger.kernel.org
Cc: lorenzo.bianconi@redhat.com, davem@davemloft.net,
	kuba@kernel.org, ast@kernel.org, daniel@iogearbox.net,
	shayagr@amazon.com, john.fastabend@gmail.com, dsahern@kernel.org,
	brouer@redhat.com, echaudro@redhat.com, jasowang@redhat.com,
	alexander.duyck@gmail.com, saeed@kernel.org,
	maciej.fijalkowski@intel.com, magnus.karlsson@intel.com,
	tirthendu.sarkar@intel.com, toke@redhat.com
Subject: [PATCH v14 bpf-next 02/18] xdp: introduce flags field in xdp_buff/xdp_frame
Date: Fri, 10 Sep 2021 18:14:08 +0200	[thread overview]
Message-ID: <b74dac5c5bfe5115dd777d0eafcb0c3c21853348.1631289870.git.lorenzo@kernel.org> (raw)
In-Reply-To: <cover.1631289870.git.lorenzo@kernel.org>

Introduce flags field in xdp_frame and xdp_buffer data structures
to define additional buffer features. At the moment the only
supported buffer feature is multi-buffer bit (mb). Multi-buffer bit
is used to specify if this is a linear buffer (mb = 0) or a multi-buffer
frame (mb = 1). In the latter case the driver is expected to initialize
the skb_shared_info structure at the end of the first buffer to link
together subsequent buffers belonging to the same frame.

Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 include/net/xdp.h | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/include/net/xdp.h b/include/net/xdp.h
index ad5b02dcb6f4..fd31cc33aa4f 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -66,6 +66,10 @@ struct xdp_txq_info {
 	struct net_device *dev;
 };
 
+enum xdp_buff_flags {
+	XDP_FLAGS_MULTI_BUFF	= BIT(0), /* non-linear xdp buff */
+};
+
 struct xdp_buff {
 	void *data;
 	void *data_end;
@@ -74,13 +78,30 @@ struct xdp_buff {
 	struct xdp_rxq_info *rxq;
 	struct xdp_txq_info *txq;
 	u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/
+	u32 flags; /* supported values defined in xdp_buff_flags */
 };
 
+static __always_inline bool xdp_buff_is_mb(struct xdp_buff *xdp)
+{
+	return !!(xdp->flags & XDP_FLAGS_MULTI_BUFF);
+}
+
+static __always_inline void xdp_buff_set_mb(struct xdp_buff *xdp)
+{
+	xdp->flags |= XDP_FLAGS_MULTI_BUFF;
+}
+
+static __always_inline void xdp_buff_clear_mb(struct xdp_buff *xdp)
+{
+	xdp->flags &= ~XDP_FLAGS_MULTI_BUFF;
+}
+
 static __always_inline void
 xdp_init_buff(struct xdp_buff *xdp, u32 frame_sz, struct xdp_rxq_info *rxq)
 {
 	xdp->frame_sz = frame_sz;
 	xdp->rxq = rxq;
+	xdp->flags = 0;
 }
 
 static __always_inline void
@@ -122,8 +143,14 @@ struct xdp_frame {
 	 */
 	struct xdp_mem_info mem;
 	struct net_device *dev_rx; /* used by cpumap */
+	u32 flags; /* supported values defined in xdp_buff_flags */
 };
 
+static __always_inline bool xdp_frame_is_mb(struct xdp_frame *frame)
+{
+	return !!(frame->flags & XDP_FLAGS_MULTI_BUFF);
+}
+
 #define XDP_BULK_QUEUE_SIZE	16
 struct xdp_frame_bulk {
 	int count;
@@ -180,6 +207,7 @@ void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
 	xdp->data_end = frame->data + frame->len;
 	xdp->data_meta = frame->data - frame->metasize;
 	xdp->frame_sz = frame->frame_sz;
+	xdp->flags = frame->flags;
 }
 
 static inline
@@ -206,6 +234,7 @@ int xdp_update_frame_from_buff(struct xdp_buff *xdp,
 	xdp_frame->headroom = headroom - sizeof(*xdp_frame);
 	xdp_frame->metasize = metasize;
 	xdp_frame->frame_sz = xdp->frame_sz;
+	xdp_frame->flags = xdp->flags;
 
 	return 0;
 }
-- 
2.31.1

