netdev - [PATCH bpf-next 04/13] ice: use the xsk batched rx allocation interface

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Date:   Wed, 22 Sep 2021 09:56:04 +0200
From:   Magnus Karlsson <magnus.karlsson@...il.com>
To:     magnus.karlsson@...el.com, bjorn@...nel.org, ast@...nel.org,
        daniel@...earbox.net, netdev@...r.kernel.org,
        maciej.fijalkowski@...el.com, ciara.loftus@...el.com
Cc:     jonathan.lemon@...il.com, bpf@...r.kernel.org,
        anthony.l.nguyen@...el.com
Subject: [PATCH bpf-next 04/13] ice: use the xsk batched rx allocation interface

From: Magnus Karlsson <magnus.karlsson@...el.com>

Use the new xsk batched rx allocation interface for the zero-copy data
path. As the array of struct xdp_buff pointers kept by the driver is
really a ring that wraps, the allocation routine is modified to detect
a wrap and in that case call the allocation function twice. The
allocation function cannot deal with wrapped rings, only arrays. As we
now know exactly how many buffers we get and that there is no
wrapping, the allocation function can be simplified even more as all
if-statements in the allocation loop can be removed, improving
performance.

Signed-off-by: Magnus Karlsson <magnus.karlsson@...el.com>
---
 drivers/net/ethernet/intel/ice/ice_xsk.c | 44 ++++++++++--------------
 1 file changed, 19 insertions(+), 25 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c
index f4ab5259a56c..7682eaa9a9ec 100644
--- a/drivers/net/ethernet/intel/ice/ice_xsk.c
+++ b/drivers/net/ethernet/intel/ice/ice_xsk.c
@@ -365,44 +365,38 @@ bool ice_alloc_rx_bufs_zc(struct ice_ring *rx_ring, u16 count)
 	union ice_32b_rx_flex_desc *rx_desc;
 	u16 ntu = rx_ring->next_to_use;
 	struct xdp_buff **xdp;
-	bool ok = true;
+	u32 nb_buffs, i;
 	dma_addr_t dma;
 
-	if (!count)
-		return true;
-
 	rx_desc = ICE_RX_DESC(rx_ring, ntu);
 	xdp = &rx_ring->xdp_buf[ntu];
 
-	do {
-		*xdp = xsk_buff_alloc(rx_ring->xsk_pool);
-		if (!xdp) {
-			ok = false;
-			break;
-		}
+	nb_buffs = min_t(u16, count, rx_ring->count - ntu);
+	nb_buffs = xsk_buff_alloc_batch(rx_ring->xsk_pool, xdp, nb_buffs);
+	if (!nb_buffs)
+		return false;
 
+	i = nb_buffs;
+	while (i--) {
 		dma = xsk_buff_xdp_get_dma(*xdp);
 		rx_desc->read.pkt_addr = cpu_to_le64(dma);
-		rx_desc->wb.status_error0 = 0;
 
 		rx_desc++;
 		xdp++;
-		ntu++;
-
-		if (unlikely(ntu == rx_ring->count)) {
-			rx_desc = ICE_RX_DESC(rx_ring, 0);
-			xdp = rx_ring->xdp_buf;
-			ntu = 0;
-		}
-	} while (--count);
+	}
 
-	if (rx_ring->next_to_use != ntu) {
-		/* clear the status bits for the next_to_use descriptor */
-		rx_desc->wb.status_error0 = 0;
-		ice_release_rx_desc(rx_ring, ntu);
+	ntu += nb_buffs;
+	if (ntu == rx_ring->count) {
+		rx_desc = ICE_RX_DESC(rx_ring, 0);
+		xdp = rx_ring->xdp_buf;
+		ntu = 0;
 	}
 
-	return ok;
+	/* clear the status bits for the next_to_use descriptor */
+	rx_desc->wb.status_error0 = 0;
+	ice_release_rx_desc(rx_ring, ntu);
+
+	return count == nb_buffs ? true : false;
 }
 
 /**
@@ -545,7 +539,7 @@ int ice_clean_rx_irq_zc(struct ice_ring *rx_ring, int budget)
 			break;
 
 		xdp = &rx_ring->xdp_buf[rx_ring->next_to_clean];
-		(*xdp)->data_end = (*xdp)->data + size;
+		xsk_buff_set_size(*xdp, size);
 		xsk_buff_dma_sync_for_cpu(*xdp, rx_ring->xsk_pool);
 
 		xdp_res = ice_run_xdp_zc(rx_ring, *xdp);
-- 
2.29.0