On 13/04/2023 05.25, Song Yoong Siang wrote:
Introduce struct stmmac_xdp_buff as a preparation to support XDP Rx
metadata via kfuncs.
Reviewed-by: Jacob Keller <jacob.e.keller@xxxxxxxxx>
Signed-off-by: Song Yoong Siang <yoong.siang.song@xxxxxxxxx>
---
drivers/net/ethernet/stmicro/stmmac/stmmac.h | 4 ++++
.../net/ethernet/stmicro/stmmac/stmmac_main.c | 18 +++++++++---------
2 files changed, 13 insertions(+), 9 deletions(-)
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index 3d15e1e92e18..ac8ccf851708 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -92,6 +92,10 @@ struct stmmac_rx_buffer {
dma_addr_t sec_addr;
};
+struct stmmac_xdp_buff {
+ struct xdp_buff xdp;
+};
+
struct stmmac_rx_queue {
u32 rx_count_frames;
u32 queue_index;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index d7fcab057032..6ffce52ca837 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -5188,9 +5188,9 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
int status = 0, coe = priv->hw->rx_csum;
unsigned int next_entry = rx_q->cur_rx;
enum dma_data_direction dma_dir;
+ struct stmmac_xdp_buff ctx = {};
This code trick {} will zero out the struct.
Is this done purpose and really needed?
On x86_64 this unfortunately generates an asm instruction: rep stos
A repeated store string operation, for zeroing out memory, which is
slow. (Because[1] it supports be suspended by an exception or interrupt,
which requires it to store/restore CPU flags).
[1] https://www.felixcloutier.com/x86/rep:repe:repz:repne:repnz#tbl-4-22
unsigned int desc_size;
struct sk_buff *skb = NULL;
- struct xdp_buff xdp;
int xdp_status = 0;
int buf_sz;
@@ -5311,17 +5311,17 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
dma_sync_single_for_cpu(priv->device, buf->addr,
buf1_len, dma_dir);
- xdp_init_buff(&xdp, buf_sz, &rx_q->xdp_rxq);
- xdp_prepare_buff(&xdp, page_address(buf->page),
+ xdp_init_buff(&ctx.xdp, buf_sz, &rx_q->xdp_rxq);
+ xdp_prepare_buff(&ctx.xdp, page_address(buf->page),
buf->page_offset, buf1_len, false);
- pre_len = xdp.data_end - xdp.data_hard_start -
+ pre_len = ctx.xdp.data_end - ctx.xdp.data_hard_start -
buf->page_offset;
- skb = stmmac_xdp_run_prog(priv, &xdp);
+ skb = stmmac_xdp_run_prog(priv, &ctx.xdp);
/* Due xdp_adjust_tail: DMA sync for_device
* cover max len CPU touch
*/
- sync_len = xdp.data_end - xdp.data_hard_start -
+ sync_len = ctx.xdp.data_end - ctx.xdp.data_hard_start -
buf->page_offset;
sync_len = max(sync_len, pre_len);
@@ -5331,7 +5331,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
if (xdp_res & STMMAC_XDP_CONSUMED) {
page_pool_put_page(rx_q->page_pool,
- virt_to_head_page(xdp.data),
+ virt_to_head_page(ctx.xdp.data),
sync_len, true);
buf->page = NULL;
priv->dev->stats.rx_dropped++;
@@ -5359,7 +5359,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
if (!skb) {
/* XDP program may expand or reduce tail */
- buf1_len = xdp.data_end - xdp.data;
+ buf1_len = ctx.xdp.data_end - ctx.xdp.data;
skb = napi_alloc_skb(&ch->rx_napi, buf1_len);
if (!skb) {
@@ -5369,7 +5369,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
}
/* XDP program may adjust header */
- skb_copy_to_linear_data(skb, xdp.data, buf1_len);
+ skb_copy_to_linear_data(skb, ctx.xdp.data, buf1_len);
skb_put(skb, buf1_len);
/* Data payload copied into SKB, page ready for recycle */
