[PATCH net-next v4 06/15] net: ethernet: cortina: Index free queue fragments with XArray

@@ -38,6 +38,7 @@
 #include <linux/ethtool.h>
 #include <linux/tcp.h>
 #include <linux/u64_stats_sync.h>
+#include <linux/xarray.h>
 
 #include <linux/in.h>
 #include <linux/ip.h>

@@ -167,6 +168,7 @@ struct gemini_ethernet {
 	struct gmac_rxdesc *freeq_ring;
 	dma_addr_t	freeq_dma_base;
 	struct gmac_queue_page	*freeq_pages;
+	struct xarray	freeq_mappings;
 	unsigned int	num_freeq_pages;
 	spinlock_t	freeq_lock; /* Locks queue from reentrance */
 };

@@ -726,43 +728,47 @@ static int gmac_setup_rxq(struct net_device *netdev)
 	return 0;
 }
 
+static unsigned long
+geth_freeq_mapping_index(const struct gemini_ethernet *geth,
+			 dma_addr_t mapping)
+{
+	return (unsigned long)(mapping >> geth->freeq_frag_order);
+}
+
 static struct page *geth_freeq_lookup(struct gemini_ethernet *geth,
 				      dma_addr_t mapping,
 				      unsigned int *page_offs)
 {
 	unsigned int frag_len = 1 << geth->freeq_frag_order;
 	struct gmac_queue_page *gpage;
+	unsigned long index;
 	unsigned long flags;
 	dma_addr_t page_mapping;
-	struct page *page = NULL;
-	int i;
-
-	spin_lock_irqsave(&geth->freeq_lock, flags);
-	if (!geth->freeq_pages) {
-		dev_err_ratelimited(geth->dev,
-				    "try to get page with no page list\n");
-		goto unlock;
-	}
-
-	/* Look up a ring buffer page from virtual mapping */
-	for (i = 0; i < geth->num_freeq_pages; i++) {
-		gpage = &geth->freeq_pages[i];
-		if (!gpage->page || mapping < gpage->mapping)
-			continue;
-
-		page_mapping = gpage->mapping;
-		if (mapping - page_mapping > PAGE_SIZE - frag_len ||
-		    ((mapping - page_mapping) & (frag_len - 1)))
-			continue;
+	struct page *page;
+	bool valid;
 
-		page = gpage->page;
-		*page_offs = mapping - page_mapping;
-		break;
-	}
+	index = geth_freeq_mapping_index(geth, mapping);
 
-unlock:
+	spin_lock_irqsave(&geth->freeq_lock, flags);
+	gpage = xa_load(&geth->freeq_mappings, index);
+	if (!gpage || !gpage->page)
+		goto err_unlock;
+
+	page = gpage->page;
+	page_mapping = gpage->mapping;
+	valid = mapping >= page_mapping &&
+		mapping - page_mapping <= PAGE_SIZE - frag_len &&
+		!((mapping - page_mapping) & (frag_len - 1));
+	if (!valid)
+		goto err_unlock;
+
+	*page_offs = mapping - page_mapping;
 	spin_unlock_irqrestore(&geth->freeq_lock, flags);
 	return page;
+
+err_unlock:
+	spin_unlock_irqrestore(&geth->freeq_lock, flags);
+	return NULL;
 }
 
 static void gmac_cleanup_rxq(struct net_device *netdev)

@@ -821,12 +827,16 @@ static struct page *geth_freeq_alloc_map_page(struct gemini_ethernet *geth,
 	struct gmac_rxdesc *freeq_entry;
 	struct gmac_queue_page *gpage;
 	unsigned int fpp_order;
+	unsigned int fragments;
 	unsigned int frag_len;
 	dma_addr_t page_mapping;
 	dma_addr_t mapping;
 	struct page *page;
+	int ret;
 	int i;
 
+	lockdep_assert_held(&geth->freeq_lock);
+
 	/* First allocate and DMA map a single page */
 	page = alloc_page(GFP_ATOMIC);
 	if (!page)

@@ -855,9 +865,26 @@ static struct page *geth_freeq_alloc_map_page(struct gemini_ethernet *geth,
 	 */
 	frag_len = 1 << geth->freeq_frag_order; /* Usually 2048 */
 	fpp_order = PAGE_SHIFT - geth->freeq_frag_order;
+	fragments = 1 << fpp_order;
+
 	gpage = &geth->freeq_pages[pn];
-	if (gpage->page)
+	for (i = 0; i < fragments; i++) {
+		mapping = page_mapping + i * frag_len;
+		ret = xa_insert(&geth->freeq_mappings,
+				geth_freeq_mapping_index(geth, mapping),
+				gpage, GFP_ATOMIC);
+		if (ret)
+			goto err_mappings;
+	}
+
+	if (gpage->page) {
+		for (i = 0; i < fragments; i++) {
+			mapping = gpage->mapping + i * frag_len;
+			xa_erase(&geth->freeq_mappings,
+				 geth_freeq_mapping_index(geth, mapping));
+		}
 		put_page(gpage->page);
+	}
 
 	/* Then put our new mapping into the page table */
 	gpage->mapping = page_mapping;

@@ -876,6 +903,17 @@ static struct page *geth_freeq_alloc_map_page(struct gemini_ethernet *geth,
 		pn, &page_mapping, page);
 
 	return page;
+
+err_mappings:
+	while (i--) {
+		mapping = page_mapping + i * frag_len;
+		xa_erase(&geth->freeq_mappings,
+			 geth_freeq_mapping_index(geth, mapping));
+	}
+	dma_unmap_single(geth->dev, page_mapping, PAGE_SIZE,
+			 DMA_FROM_DEVICE);
+	put_page(page);
+	return NULL;
 }
 
 /**

@@ -948,6 +986,8 @@ static int geth_setup_freeq(struct gemini_ethernet *geth)
 	unsigned int pages = len >> fpp_order;
 	union queue_threshold qt;
 	union dma_skb_size skbsz;
+	unsigned long flags;
+	struct page *page;
 	unsigned int filled;
 	unsigned int pn;
 

@@ -961,16 +1001,20 @@ static int geth_setup_freeq(struct gemini_ethernet *geth)
 		goto err_freeq;
 	}
 
-	/* Allocate a mapping to page look-up index */
+	/* Allocate page metadata referenced by the mapping index */
 	geth->freeq_pages = kzalloc_objs(*geth->freeq_pages, pages);
 	if (!geth->freeq_pages)
 		goto err_freeq;
 	geth->num_freeq_pages = pages;
 
 	dev_info(geth->dev, "allocate %d pages for queue\n", pages);
-	for (pn = 0; pn < pages; pn++)
-		if (!geth_freeq_alloc_map_page(geth, pn))
+	for (pn = 0; pn < pages; pn++) {
+		spin_lock_irqsave(&geth->freeq_lock, flags);
+		page = geth_freeq_alloc_map_page(geth, pn);
+		spin_unlock_irqrestore(&geth->freeq_lock, flags);
+		if (!page)
 			goto err_freeq_alloc;
+	}
 
 	/* Discard pointer state belonging to the previous queue geometry. */
 	writel(0, geth->base + GLOBAL_SWFQ_RWPTR_REG);

@@ -1000,6 +1044,7 @@ static int geth_setup_freeq(struct gemini_ethernet *geth)
 				 DMA_FROM_DEVICE);
 		put_page(gpage->page);
 	}
+	xa_destroy(&geth->freeq_mappings);
 
 	kfree(geth->freeq_pages);
 	geth->freeq_pages = NULL;

@@ -1041,6 +1086,7 @@ static void geth_cleanup_freeq(struct gemini_ethernet *geth)
 		while (page_ref_count(gpage->page) > 0)
 			put_page(gpage->page);
 	}
+	xa_destroy(&geth->freeq_mappings);
 
 	kfree(geth->freeq_pages);
 	geth->freeq_pages = NULL;

@@ -2740,6 +2786,7 @@ static int gemini_ethernet_probe(struct platform_device *pdev)
 
 	spin_lock_init(&geth->irq_lock);
 	spin_lock_init(&geth->freeq_lock);
+	xa_init(&geth->freeq_mappings);
 
 	/* The children will use this */
 	platform_set_drvdata(pdev, geth);