Merge branch 'mvneta-access-skb_shared_info-only-on-last-frag'

Lorenzo Bianconi says:

====================
mvneta: access skb_shared_info only on last frag

Build skb_shared_info on mvneta_rx_swbm stack and sync it to xdp_buff
skb_shared_info area only on the last fragment.
Avoid avoid unnecessary xdp_buff initialization in mvneta_rx_swbm routine.
This a preliminary series to complete xdp multi-buff in mvneta driver.
====================

Link: https://lore.kernel.org/r/cover.1605889258.git.lorenzo@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/marvell/mvneta.c

@@ -2033,16 +2033,16 @@ int mvneta_rx_refill_queue(struct mvneta_port *pp, struct mvneta_rx_queue *rxq)
 
 static void
 mvneta_xdp_put_buff(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
-		    struct xdp_buff *xdp, int sync_len, bool napi)
+		    struct xdp_buff *xdp, struct skb_shared_info *sinfo,
+		    int sync_len)
 {
-	struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
 	int i;
 
 	for (i = 0; i < sinfo->nr_frags; i++)
 		page_pool_put_full_page(rxq->page_pool,
-					skb_frag_page(&sinfo->frags[i]), napi);
+					skb_frag_page(&sinfo->frags[i]), true);
 	page_pool_put_page(rxq->page_pool, virt_to_head_page(xdp->data),
-			   sync_len, napi);
+			   sync_len, true);
 }
 
 static int
@@ -2179,6 +2179,7 @@ mvneta_run_xdp(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
 	       struct bpf_prog *prog, struct xdp_buff *xdp,
 	       u32 frame_sz, struct mvneta_stats *stats)
 {
+	struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
 	unsigned int len, data_len, sync;
 	u32 ret, act;
 
@@ -2199,7 +2200,7 @@ mvneta_run_xdp(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
 
 		err = xdp_do_redirect(pp->dev, xdp, prog);
 		if (unlikely(err)) {
-			mvneta_xdp_put_buff(pp, rxq, xdp, sync, true);
+			mvneta_xdp_put_buff(pp, rxq, xdp, sinfo, sync);
 			ret = MVNETA_XDP_DROPPED;
 		} else {
 			ret = MVNETA_XDP_REDIR;
@@ -2210,7 +2211,7 @@ mvneta_run_xdp(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
 	case XDP_TX:
 		ret = mvneta_xdp_xmit_back(pp, xdp);
 		if (ret != MVNETA_XDP_TX)
-			mvneta_xdp_put_buff(pp, rxq, xdp, sync, true);
+			mvneta_xdp_put_buff(pp, rxq, xdp, sinfo, sync);
 		break;
 	default:
 		bpf_warn_invalid_xdp_action(act);
@@ -2219,7 +2220,7 @@ mvneta_run_xdp(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
 		trace_xdp_exception(pp->dev, prog, act);
 		fallthrough;
 	case XDP_DROP:
-		mvneta_xdp_put_buff(pp, rxq, xdp, sync, true);
+		mvneta_xdp_put_buff(pp, rxq, xdp, sinfo, sync);
 		ret = MVNETA_XDP_DROPPED;
 		stats->xdp_drop++;
 		break;
@@ -2277,9 +2278,9 @@ mvneta_swbm_add_rx_fragment(struct mvneta_port *pp,
 			    struct mvneta_rx_desc *rx_desc,
 			    struct mvneta_rx_queue *rxq,
 			    struct xdp_buff *xdp, int *size,
+			    struct skb_shared_info *xdp_sinfo,
 			    struct page *page)
 {
-	struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp);
 	struct net_device *dev = pp->dev;
 	enum dma_data_direction dma_dir;
 	int data_len, len;
@@ -2297,13 +2298,22 @@ mvneta_swbm_add_rx_fragment(struct mvneta_port *pp,
 				len, dma_dir);
 	rx_desc->buf_phys_addr = 0;
 
-	if (data_len > 0 && sinfo->nr_frags < MAX_SKB_FRAGS) {
-		skb_frag_t *frag = &sinfo->frags[sinfo->nr_frags];
+	if (data_len > 0 && xdp_sinfo->nr_frags < MAX_SKB_FRAGS) {
+		skb_frag_t *frag = &xdp_sinfo->frags[xdp_sinfo->nr_frags++];
 
 		skb_frag_off_set(frag, pp->rx_offset_correction);
 		skb_frag_size_set(frag, data_len);
 		__skb_frag_set_page(frag, page);
-		sinfo->nr_frags++;
+
+		/* last fragment */
+		if (len == *size) {
+			struct skb_shared_info *sinfo;
+
+			sinfo = xdp_get_shared_info_from_buff(xdp);
+			sinfo->nr_frags = xdp_sinfo->nr_frags;
+			memcpy(sinfo->frags, xdp_sinfo->frags,
+			       sinfo->nr_frags * sizeof(skb_frag_t));
+		}
 	} else {
 		page_pool_put_full_page(rxq->page_pool, page, true);
 	}
@@ -2347,13 +2357,17 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
 {
 	int rx_proc = 0, rx_todo, refill, size = 0;
 	struct net_device *dev = pp->dev;
-	struct xdp_buff xdp_buf = {
-		.frame_sz = PAGE_SIZE,
-		.rxq = &rxq->xdp_rxq,
-	};
+	struct skb_shared_info sinfo;
 	struct mvneta_stats ps = {};
 	struct bpf_prog *xdp_prog;
 	u32 desc_status, frame_sz;
+	struct xdp_buff xdp_buf;
+
+	xdp_buf.data_hard_start = NULL;
+	xdp_buf.frame_sz = PAGE_SIZE;
+	xdp_buf.rxq = &rxq->xdp_rxq;
+
+	sinfo.nr_frags = 0;
 
 	/* Get number of received packets */
 	rx_todo = mvneta_rxq_busy_desc_num_get(pp, rxq);
@@ -2393,11 +2407,11 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
 				rx_desc->buf_phys_addr = 0;
 				page_pool_put_full_page(rxq->page_pool, page,
 							true);
-				continue;
+				goto next;
 			}
 
 			mvneta_swbm_add_rx_fragment(pp, rx_desc, rxq, &xdp_buf,
-						    &size, page);
+						    &size, &sinfo, page);
 		} /* Middle or Last descriptor */
 
 		if (!(rx_status & MVNETA_RXD_LAST_DESC))
@@ -2405,7 +2419,7 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
 			continue;
 
 		if (size) {
-			mvneta_xdp_put_buff(pp, rxq, &xdp_buf, -1, true);
+			mvneta_xdp_put_buff(pp, rxq, &xdp_buf, &sinfo, -1);
 			goto next;
 		}
 
@@ -2417,7 +2431,7 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
 		if (IS_ERR(skb)) {
 			struct mvneta_pcpu_stats *stats = this_cpu_ptr(pp->stats);
 
-			mvneta_xdp_put_buff(pp, rxq, &xdp_buf, -1, true);
+			mvneta_xdp_put_buff(pp, rxq, &xdp_buf, &sinfo, -1);
 
 			u64_stats_update_begin(&stats->syncp);
 			stats->es.skb_alloc_error++;
@@ -2434,11 +2448,12 @@ static int mvneta_rx_swbm(struct napi_struct *napi,
 		napi_gro_receive(napi, skb);
 next:
 		xdp_buf.data_hard_start = NULL;
+		sinfo.nr_frags = 0;
 	}
 	rcu_read_unlock();
 
 	if (xdp_buf.data_hard_start)
-		mvneta_xdp_put_buff(pp, rxq, &xdp_buf, -1, true);
+		mvneta_xdp_put_buff(pp, rxq, &xdp_buf, &sinfo, -1);
 
 	if (ps.xdp_redirect)
 		xdp_do_flush_map();