kernel: solos-pci: Increase headroom on received packets

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
SVN-Revision: 46993

diff --git a/target/linux/generic/patches-3.18/083-solos-pci-Increase-headroom-on-received-packets.patch b/target/linux/generic/patches-3.18/083-solos-pci-Increase-headroom-on-received-packets.patch
new file mode 100644 (file)
index 0000000..7f9f926
--- /dev/null
+++ b/target/linux/generic/patches-3.18/083-solos-pci-Increase-headroom-on-received-packets.patch
@@ -0,0 +1,54 @@
+From: David Woodhouse <dwmw2@infradead.org>
+Date: Thu, 17 Sep 2015 11:19:53 +0100
+Subject: [PATCH] solos-pci: Increase headroom on received packets
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+A comment in include/linux/skbuff.h says that:
+
+ * Various parts of the networking layer expect at least 32 bytes of
+ * headroom, you should not reduce this.
+
+This was demonstrated by a panic when handling fragmented IPv6 packets:
+http://marc.info/?l=linux-netdev&m=144236093519172&w=2
+
+It's not entirely clear if that comment is still valid — and if it is,
+perhaps netif_rx() ought to be enforcing it with a warning.
+
+But either way, it is rather stupid from a performance point of view
+for us to be receiving packets into a buffer which doesn't have enough
+room to prepend an Ethernet header — it means that *every* incoming
+packet is going to be need to be reallocated. So let's fix that.
+
+Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
+---
+
+--- a/drivers/atm/solos-pci.c
++++ b/drivers/atm/solos-pci.c
+@@ -805,7 +805,12 @@ static void solos_bh(unsigned long card_
+                                       continue;
+                               }
+ 
+-                              skb = alloc_skb(size + 1, GFP_ATOMIC);
++                              /* Use netdev_alloc_skb() because it adds NET_SKB_PAD of
++                               * headroom, and ensures we can route packets back out an
++                               * Ethernet interface (for example) without having to
++                               * reallocate. Adding NET_IP_ALIGN also ensures that both
++                               * PPPoATM and PPPoEoBR2684 packets end up aligned. */
++                              skb = netdev_alloc_skb_ip_align(NULL, size + 1);
+                               if (!skb) {
+                                       if (net_ratelimit())
+                                               dev_warn(&card->dev->dev, "Failed to allocate sk_buff for RX\n");
+@@ -869,7 +874,10 @@ static void solos_bh(unsigned long card_
+               /* Allocate RX skbs for any ports which need them */
+               if (card->using_dma && card->atmdev[port] &&
+                   !card->rx_skb[port]) {
+-                      struct sk_buff *skb = alloc_skb(RX_DMA_SIZE, GFP_ATOMIC);
++                      /* Unlike the MMIO case (qv) we can't add NET_IP_ALIGN
++                       * here; the FPGA can only DMA to addresses which are
++                       * aligned to 4 bytes. */
++                      struct sk_buff *skb = dev_alloc_skb(RX_DMA_SIZE);
+                       if (skb) {
+                               SKB_CB(skb)->dma_addr =
+                                       pci_map_single(card->dev, skb->data,

diff --git a/target/linux/generic/patches-4.1/081-solos-pci-Increase-headroom-on-received-packets.patch b/target/linux/generic/patches-4.1/081-solos-pci-Increase-headroom-on-received-packets.patch
new file mode 100644 (file)
index 0000000..605f57a
--- /dev/null
+++ b/target/linux/generic/patches-4.1/081-solos-pci-Increase-headroom-on-received-packets.patch
@@ -0,0 +1,54 @@
+From: David Woodhouse <dwmw2@infradead.org>
+Date: Thu, 17 Sep 2015 11:19:53 +0100
+Subject: [PATCH] solos-pci: Increase headroom on received packets
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+A comment in include/linux/skbuff.h says that:
+
+ * Various parts of the networking layer expect at least 32 bytes of
+ * headroom, you should not reduce this.
+
+This was demonstrated by a panic when handling fragmented IPv6 packets:
+http://marc.info/?l=linux-netdev&m=144236093519172&w=2
+
+It's not entirely clear if that comment is still valid — and if it is,
+perhaps netif_rx() ought to be enforcing it with a warning.
+
+But either way, it is rather stupid from a performance point of view
+for us to be receiving packets into a buffer which doesn't have enough
+room to prepend an Ethernet header — it means that *every* incoming
+packet is going to be need to be reallocated. So let's fix that.
+
+Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
+---
+
+--- a/drivers/atm/solos-pci.c
++++ b/drivers/atm/solos-pci.c
+@@ -805,7 +805,12 @@ static void solos_bh(unsigned long card_
+                                       continue;
+                               }
+ 
+-                              skb = alloc_skb(size + 1, GFP_ATOMIC);
++                              /* Use netdev_alloc_skb() because it adds NET_SKB_PAD of
++                               * headroom, and ensures we can route packets back out an
++                               * Ethernet interface (for example) without having to
++                               * reallocate. Adding NET_IP_ALIGN also ensures that both
++                               * PPPoATM and PPPoEoBR2684 packets end up aligned. */
++                              skb = netdev_alloc_skb_ip_align(NULL, size + 1);
+                               if (!skb) {
+                                       if (net_ratelimit())
+                                               dev_warn(&card->dev->dev, "Failed to allocate sk_buff for RX\n");
+@@ -869,7 +874,10 @@ static void solos_bh(unsigned long card_
+               /* Allocate RX skbs for any ports which need them */
+               if (card->using_dma && card->atmdev[port] &&
+                   !card->rx_skb[port]) {
+-                      struct sk_buff *skb = alloc_skb(RX_DMA_SIZE, GFP_ATOMIC);
++                      /* Unlike the MMIO case (qv) we can't add NET_IP_ALIGN
++                       * here; the FPGA can only DMA to addresses which are
++                       * aligned to 4 bytes. */
++                      struct sk_buff *skb = dev_alloc_skb(RX_DMA_SIZE);
+                       if (skb) {
+                               SKB_CB(skb)->dma_addr =
+                                       dma_map_single(&card->dev->dev, skb->data,