netdev - [PATCH v23 bpf-next 02/23] xdp: introduce flags field in xdp_buff/xdp

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Message-Id: <e389f14f3a162c0a5bc6a2e1aa8dd01a90be117d.1642758637.git.lorenzo@kernel.org>
Date:   Fri, 21 Jan 2022 11:09:45 +0100
From:   Lorenzo Bianconi <lorenzo@...nel.org>
To:     bpf@...r.kernel.org, netdev@...r.kernel.org
Cc:     lorenzo.bianconi@...hat.com, davem@...emloft.net, kuba@...nel.org,
        ast@...nel.org, daniel@...earbox.net, shayagr@...zon.com,
        john.fastabend@...il.com, dsahern@...nel.org, brouer@...hat.com,
        echaudro@...hat.com, jasowang@...hat.com,
        alexander.duyck@...il.com, saeed@...nel.org,
        maciej.fijalkowski@...el.com, magnus.karlsson@...el.com,
        tirthendu.sarkar@...el.com, toke@...hat.com,
        andrii.nakryiko@...il.com
Subject: [PATCH v23 bpf-next 02/23] xdp: introduce flags field in xdp_buff/xdp_frame

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 frags bit (XDP_FLAGS_HAS_FRAGS).
frags bit is used to specify if this is a linear buffer
(XDP_FLAGS_HAS_FRAGS not set) or a frags frame (XDP_FLAGS_HAS_FRAGS
set). 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: Toke Hoiland-Jorgensen <toke@...hat.com>
Acked-by: John Fastabend <john.fastabend@...il.com>
Acked-by: Jesper Dangaard Brouer <brouer@...hat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
---
 include/net/xdp.h | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/include/net/xdp.h b/include/net/xdp.h
index 8f0812e4996d..485e9495a690 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_HAS_FRAGS	= 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_has_frags(struct xdp_buff *xdp)
+{
+	return !!(xdp->flags & XDP_FLAGS_HAS_FRAGS);
+}
+
+static __always_inline void xdp_buff_set_frags_flag(struct xdp_buff *xdp)
+{
+	xdp->flags |= XDP_FLAGS_HAS_FRAGS;
+}
+
+static __always_inline void xdp_buff_clear_frags_flag(struct xdp_buff *xdp)
+{
+	xdp->flags &= ~XDP_FLAGS_HAS_FRAGS;
+}
+
 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_has_frags(struct xdp_frame *frame)
+{
+	return !!(frame->flags & XDP_FLAGS_HAS_FRAGS);
+}
+
 #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;
 }
-- 
2.34.1