From: Haiyang Zhang <haiyangz@microsoft.com>

Date: Fri, 28 Jan 2022 18:03:38 -0800

Patch-mainline: v5.18-rc1

Subject: net: mana: Reuse XDP dropped page

Git-commit: a6bf5703f17bdbd775c0e6837dd2d5b1c344e28c

References: bsc#1195651

Reuse the dropped page in RX path to save page allocation

overhead.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>

Signed-off-by: David S. Miller <davem@davemloft.net>

Acked-by: Olaf Hering <ohering@suse.de>

---

 drivers/net/ethernet/microsoft/mana/mana.h    |  1 +

 drivers/net/ethernet/microsoft/mana/mana_en.c | 15 +++++++++++++--

 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/microsoft/mana/mana.h b/drivers/net/ethernet/microsoft/mana/mana.h

--- a/drivers/net/ethernet/microsoft/mana/mana.h

+++ b/drivers/net/ethernet/microsoft/mana/mana.h

@@ -310,6 +310,7 @@ struct mana_rxq {

 	struct bpf_prog __rcu *bpf_prog;

 	struct xdp_rxq_info xdp_rxq;

+	struct page *xdp_save_page;

 	/* MUST BE THE LAST MEMBER:

 	 * Each receive buffer has an associated mana_recv_buf_oob.

diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c

--- a/drivers/net/ethernet/microsoft/mana/mana_en.c

+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c

@@ -1059,7 +1059,9 @@ drop_xdp:

 	u64_stats_update_end(&rx_stats->syncp);

 drop:

-	free_page((unsigned long)buf_va);

+	WARN_ON_ONCE(rxq->xdp_save_page);

+	rxq->xdp_save_page = virt_to_page(buf_va);

+

 	++ndev->stats.rx_dropped;

 	return;

@@ -1116,7 +1118,13 @@ static void mana_process_rx_cqe(struct mana_rxq *rxq, struct mana_cq *cq,

 	rxbuf_oob = &rxq->rx_oobs[curr];

 	WARN_ON_ONCE(rxbuf_oob->wqe_inf.wqe_size_in_bu != 1);

-	new_page = alloc_page(GFP_ATOMIC);

+	/* Reuse XDP dropped page if available */

+	if (rxq->xdp_save_page) {

+		new_page = rxq->xdp_save_page;

+		rxq->xdp_save_page = NULL;

+	} else {

+		new_page = alloc_page(GFP_ATOMIC);

+	}

 	if (new_page) {

 		da = dma_map_page(dev, new_page, XDP_PACKET_HEADROOM, rxq->datasize,

@@ -1403,6 +1411,9 @@ static void mana_destroy_rxq(struct mana_port_context *apc,

 	mana_deinit_cq(apc, &rxq->rx_cq);

+	if (rxq->xdp_save_page)

+		__free_page(rxq->xdp_save_page);

+

 	for (i = 0; i < rxq->num_rx_buf; i++) {

 		rx_oob = &rxq->rx_oobs[i];