[PATCH] e1000: Fix Desc. Rings and Jumbo Frames

This patch contains two fixes.  The first fix is to the tx and rx descriptor rings clean up process.  The second fix is to jumbo frames, which cleans up the code logic and removes most of the fifo related limitations on jumbo frames.  This is because the driver code now supports splitting a packet across multiple descriptors.
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: John Ronciak <john.ronciak@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

drivers/net/e1000/e1000_main.c

@@ -1542,6 +1542,8 @@ setup_rx_desc_die:
 
 	rxdr->next_to_clean = 0;
 	rxdr->next_to_use = 0;
+	rxdr->rx_skb_top = NULL;
+	rxdr->rx_skb_prev = NULL;
 
 	return 0;
 }
@@ -2010,10 +2012,12 @@ e1000_clean_rx_ring(struct e1000_adapter *adapter,
 
 			dev_kfree_skb(buffer_info->skb);
 			buffer_info->skb = NULL;
-
-			for(j = 0; j < adapter->rx_ps_pages; j++) {
-				if(!ps_page->ps_page[j]) break;
-				pci_unmap_single(pdev,
+		}
+		ps_page = &rx_ring->ps_page[i];
+		ps_page_dma = &rx_ring->ps_page_dma[i];
+		for (j = 0; j < adapter->rx_ps_pages; j++) {
+			if (!ps_page->ps_page[j]) break;
+			pci_unmap_page(pdev,
 				       ps_page_dma->ps_page_dma[j],
 				       PAGE_SIZE, PCI_DMA_FROMDEVICE);
 			ps_page_dma->ps_page_dma[j] = 0;
@@ -2021,8 +2025,17 @@ e1000_clean_rx_ring(struct e1000_adapter *adapter,
 			ps_page->ps_page[j] = NULL;
 		}
 	}
+
+	/* there also may be some cached data in our adapter */
+	if (rx_ring->rx_skb_top) {
+		dev_kfree_skb(rx_ring->rx_skb_top);
+
+		/* rx_skb_prev will be wiped out by rx_skb_top */
+		rx_ring->rx_skb_top = NULL;
+		rx_ring->rx_skb_prev = NULL;
 	}
 
+
 	size = sizeof(struct e1000_buffer) * rx_ring->count;
 	memset(rx_ring->buffer_info, 0, size);
 	size = sizeof(struct e1000_ps_page) * rx_ring->count;
@@ -2988,46 +3001,47 @@ e1000_change_mtu(struct net_device *netdev, int new_mtu)
 		return -EINVAL;
 	}
 
-#define MAX_STD_JUMBO_FRAME_SIZE 9234
-	/* might want this to be bigger enum check... */
-	/* 82571 controllers limit jumbo frame size to 10500 bytes */
-	if ((adapter->hw.mac_type == e1000_82571 || 
-	     adapter->hw.mac_type == e1000_82572) &&
-	    max_frame > MAX_STD_JUMBO_FRAME_SIZE) {
-		DPRINTK(PROBE, ERR, "MTU > 9216 bytes not supported "
-				    "on 82571 and 82572 controllers.\n");
+	/* Adapter-specific max frame size limits. */
+	switch (adapter->hw.mac_type) {
+	case e1000_82542_rev2_0:
+	case e1000_82542_rev2_1:
+	case e1000_82573:
+		if (max_frame > MAXIMUM_ETHERNET_FRAME_SIZE) {
+			DPRINTK(PROBE, ERR, "Jumbo Frames not supported.\n");
 			return -EINVAL;
 		}
-
-	if(adapter->hw.mac_type == e1000_82573 &&
-	    max_frame > MAXIMUM_ETHERNET_FRAME_SIZE) {
-		DPRINTK(PROBE, ERR, "Jumbo Frames not supported "
-				    "on 82573\n");
+		break;
+	case e1000_82571:
+	case e1000_82572:
+#define MAX_STD_JUMBO_FRAME_SIZE 9234
+		if (max_frame > MAX_STD_JUMBO_FRAME_SIZE) {
+			DPRINTK(PROBE, ERR, "MTU > 9216 not supported.\n");
 			return -EINVAL;
 		}
+		break;
+	default:
+		/* Capable of supporting up to MAX_JUMBO_FRAME_SIZE limit. */
+		break;
+	}
 
-	if(adapter->hw.mac_type > e1000_82547_rev_2) {
-		adapter->rx_buffer_len = max_frame;
+	/* since the driver code now supports splitting a packet across
+	 * multiple descriptors, most of the fifo related limitations on
+	 * jumbo frame traffic have gone away.
+	 * simply use 2k descriptors for everything.
+	 *
+	 * NOTE: dev_alloc_skb reserves 16 bytes, and typically NET_IP_ALIGN
+	 * means we reserve 2 more, this pushes us to allocate from the next
+	 * larger slab size
+	 * i.e. RXBUFFER_2048 --> size-4096 slab */
+
+	/* recent hardware supports 1KB granularity */
+	if (adapter->hw.mac_type > e1000_82547_rev_2) {
+		adapter->rx_buffer_len =
+		    ((max_frame < E1000_RXBUFFER_2048) ?
+		        max_frame : E1000_RXBUFFER_2048);
 		E1000_ROUNDUP(adapter->rx_buffer_len, 1024);
-	} else {
-		if(unlikely((adapter->hw.mac_type < e1000_82543) &&
-		   (max_frame > MAXIMUM_ETHERNET_FRAME_SIZE))) {
-			DPRINTK(PROBE, ERR, "Jumbo Frames not supported "
-					    "on 82542\n");
-			return -EINVAL;
-
-		} else {
-			if(max_frame <= E1000_RXBUFFER_2048) {
+	} else
 		adapter->rx_buffer_len = E1000_RXBUFFER_2048;
-			} else if(max_frame <= E1000_RXBUFFER_4096) {
-				adapter->rx_buffer_len = E1000_RXBUFFER_4096;
-			} else if(max_frame <= E1000_RXBUFFER_8192) {
-				adapter->rx_buffer_len = E1000_RXBUFFER_8192;
-			} else if(max_frame <= E1000_RXBUFFER_16384) {
-				adapter->rx_buffer_len = E1000_RXBUFFER_16384;
-			}
-		}
-	}
 
 	netdev->mtu = new_mtu;