From: Lorenzo Bianconi <lorenzo@kernel.org>
Date: Fri, 21 Jan 2022 11:09:46 +0100
Subject: net: mvneta: update frags bit before passing the xdp buffer to eBPF
 layer
Patch-mainline: v5.18-rc1
Git-commit: 76a676947b56710097b755d37fd7d5cea09d6e7d
References: jsc#PED-1377

Update frags bit (XDP_FLAGS_HAS_FRAGS) in xdp_buff to notify
XDP/eBPF layer and XDP remote drivers if this is a "non-linear"
XDP buffer. Access skb_shared_info only if XDP_FLAGS_HAS_FRAGS flag
is set in order to avoid possible cache-misses.

Acked-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/c00a73097f8a35860d50dae4a36e6cc9ef7e172f.1642758637.git.lorenzo@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
 drivers/net/ethernet/marvell/mvneta.c |   23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -2037,9 +2037,14 @@ mvneta_xdp_put_buff(struct mvneta_port *
 {
 	int i;
 
+	if (likely(!xdp_buff_has_frags(xdp)))
+		goto out;
+
 	for (i = 0; i < sinfo->nr_frags; i++)
 		page_pool_put_full_page(rxq->page_pool,
 					skb_frag_page(&sinfo->frags[i]), true);
+
+out:
 	page_pool_put_page(rxq->page_pool, virt_to_head_page(xdp->data),
 			   sync_len, true);
 }
@@ -2241,7 +2246,6 @@ mvneta_swbm_rx_frame(struct mvneta_port
 	int data_len = -MVNETA_MH_SIZE, len;
 	struct net_device *dev = pp->dev;
 	enum dma_data_direction dma_dir;
-	struct skb_shared_info *sinfo;
 
 	if (*size > MVNETA_MAX_RX_BUF_SIZE) {
 		len = MVNETA_MAX_RX_BUF_SIZE;
@@ -2261,11 +2265,9 @@ mvneta_swbm_rx_frame(struct mvneta_port
 
 	/* Prefetch header */
 	prefetch(data);
+	xdp_buff_clear_frags_flag(xdp);
 	xdp_prepare_buff(xdp, data, pp->rx_offset_correction + MVNETA_MH_SIZE,
 			 data_len, false);
-
-	sinfo = xdp_get_shared_info_from_buff(xdp);
-	sinfo->nr_frags = 0;
 }
 
 static void
@@ -2299,6 +2301,9 @@ mvneta_swbm_add_rx_fragment(struct mvnet
 		skb_frag_off_set(frag, pp->rx_offset_correction);
 		skb_frag_size_set(frag, data_len);
 		__skb_frag_set_page(frag, page);
+
+		if (!xdp_buff_has_frags(xdp))
+			xdp_buff_set_frags_flag(xdp);
 	} else {
 		page_pool_put_full_page(rxq->page_pool, page, true);
 	}
@@ -2320,8 +2325,12 @@ mvneta_swbm_build_skb(struct mvneta_port
 		      struct xdp_buff *xdp, u32 desc_status)
 {
 	struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
-	int i, num_frags = sinfo->nr_frags;
 	struct sk_buff *skb;
+	u8 num_frags;
+	int i;
+
+	if (unlikely(xdp_buff_has_frags(xdp)))
+		num_frags = sinfo->nr_frags;
 
 	skb = build_skb(xdp->data_hard_start, PAGE_SIZE);
 	if (!skb)
@@ -2333,6 +2342,9 @@ mvneta_swbm_build_skb(struct mvneta_port
 	skb_put(skb, xdp->data_end - xdp->data);
 	skb->ip_summed = mvneta_rx_csum(pp, desc_status);
 
+	if (likely(!xdp_buff_has_frags(xdp)))
+		goto out;
+
 	for (i = 0; i < num_frags; i++) {
 		skb_frag_t *frag = &sinfo->frags[i];
 
@@ -2341,6 +2353,7 @@ mvneta_swbm_build_skb(struct mvneta_port
 				skb_frag_size(frag), PAGE_SIZE);
 	}
 
+out:
 	return skb;
 }