enic: bug fix: split TSO fragments larger than 16K into multiple descs

enic WQ desc supports a maximum 16K buf size, so split any send fragments
larger than 16K into several descs.

Signed-off-by: Scott Feldman <scofeldm@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/enic/enic_main.c b/drivers/net/enic/enic_main.c
index 58cae6e6a59cb1e43b55a504849ca1949ef12ff8..bc5cb225ddaca093aee14a9c23ffd76617707e08 100644 (file)
--- a/drivers/net/enic/enic_main.c
+++ b/drivers/net/enic/enic_main.c
@@ -44,10 +44,15 @@
 #include "enic.h"
 
 #define ENIC_NOTIFY_TIMER_PERIOD       (2 * HZ)
+#define WQ_ENET_MAX_DESC_LEN           (1 << WQ_ENET_LEN_BITS)
+#define MAX_TSO                                (1 << 16)
+#define ENIC_DESC_MAX_SPLITS           (MAX_TSO / WQ_ENET_MAX_DESC_LEN + 1)
+
+#define PCI_DEVICE_ID_CISCO_VIC_ENET         0x0043  /* ethernet vnic */
 
 /* Supported devices */
 static struct pci_device_id enic_id_table[] = {
-       { PCI_VDEVICE(CISCO, 0x0043) },
+       { PCI_VDEVICE(CISCO, PCI_DEVICE_ID_CISCO_VIC_ENET) },
        { 0, }  /* end of table */
 };
 
@@ -310,7 +315,8 @@ static int enic_wq_service(struct vnic_dev *vdev, struct cq_desc *cq_desc,
                opaque);
 
        if (netif_queue_stopped(enic->netdev) &&
-           vnic_wq_desc_avail(&enic->wq[q_number]) >= MAX_SKB_FRAGS + 1)
+           vnic_wq_desc_avail(&enic->wq[q_number]) >=
+           (MAX_SKB_FRAGS + ENIC_DESC_MAX_SPLITS))
                netif_wake_queue(enic->netdev);
 
        spin_unlock(&enic->wq_lock[q_number]);
@@ -525,7 +531,11 @@ static inline void enic_queue_wq_skb_vlan(struct enic *enic,
        unsigned int len_left = skb->len - head_len;
        int eop = (len_left == 0);
 
-       /* Queue the main skb fragment */
+       /* Queue the main skb fragment. The fragments are no larger
+        * than max MTU(9000)+ETH_HDR_LEN(14) bytes, which is less
+        * than WQ_ENET_MAX_DESC_LEN length. So only one descriptor
+        * per fragment is queued.
+        */
        enic_queue_wq_desc(wq, skb,
                pci_map_single(enic->pdev, skb->data,
                        head_len, PCI_DMA_TODEVICE),
@@ -547,7 +557,11 @@ static inline void enic_queue_wq_skb_csum_l4(struct enic *enic,
        unsigned int csum_offset = hdr_len + skb->csum_offset;
        int eop = (len_left == 0);
 
-       /* Queue the main skb fragment */
+       /* Queue the main skb fragment. The fragments are no larger
+        * than max MTU(9000)+ETH_HDR_LEN(14) bytes, which is less
+        * than WQ_ENET_MAX_DESC_LEN length. So only one descriptor
+        * per fragment is queued.
+        */
        enic_queue_wq_desc_csum_l4(wq, skb,
                pci_map_single(enic->pdev, skb->data,
                        head_len, PCI_DMA_TODEVICE),
@@ -565,10 +579,14 @@ static inline void enic_queue_wq_skb_tso(struct enic *enic,
        struct vnic_wq *wq, struct sk_buff *skb, unsigned int mss,
        int vlan_tag_insert, unsigned int vlan_tag)
 {
-       unsigned int head_len = skb_headlen(skb);
-       unsigned int len_left = skb->len - head_len;
+       unsigned int frag_len_left = skb_headlen(skb);
+       unsigned int len_left = skb->len - frag_len_left;
        unsigned int hdr_len = skb_transport_offset(skb) + tcp_hdrlen(skb);
        int eop = (len_left == 0);
+       unsigned int len;
+       dma_addr_t dma_addr;
+       unsigned int offset = 0;
+       skb_frag_t *frag;
 
        /* Preload TCP csum field with IP pseudo hdr calculated
         * with IP length set to zero.  HW will later add in length
@@ -584,17 +602,49 @@ static inline void enic_queue_wq_skb_tso(struct enic *enic,
                        &ipv6_hdr(skb)->daddr, 0, IPPROTO_TCP, 0);
        }
 
-       /* Queue the main skb fragment */
-       enic_queue_wq_desc_tso(wq, skb,
-               pci_map_single(enic->pdev, skb->data,
-                       head_len, PCI_DMA_TODEVICE),
-               head_len,
-               mss, hdr_len,
-               vlan_tag_insert, vlan_tag,
-               eop);
+       /* Queue WQ_ENET_MAX_DESC_LEN length descriptors
+        * for the main skb fragment
+        */
+       while (frag_len_left) {
+               len = min(frag_len_left, (unsigned int)WQ_ENET_MAX_DESC_LEN);
+               dma_addr = pci_map_single(enic->pdev, skb->data + offset,
+                               len, PCI_DMA_TODEVICE);
+               enic_queue_wq_desc_tso(wq, skb,
+                       dma_addr,
+                       len,
+                       mss, hdr_len,
+                       vlan_tag_insert, vlan_tag,
+                       eop && (len == frag_len_left));
+               frag_len_left -= len;
+               offset += len;
+       }
 
-       if (!eop)
-               enic_queue_wq_skb_cont(enic, wq, skb, len_left);
+       if (eop)
+               return;
+
+       /* Queue WQ_ENET_MAX_DESC_LEN length descriptors
+        * for additional data fragments
+        */
+       for (frag = skb_shinfo(skb)->frags; len_left; frag++) {
+               len_left -= frag->size;
+               frag_len_left = frag->size;
+               offset = frag->page_offset;
+
+               while (frag_len_left) {
+                       len = min(frag_len_left,
+                               (unsigned int)WQ_ENET_MAX_DESC_LEN);
+                       dma_addr = pci_map_page(enic->pdev, frag->page,
+                               offset, len,
+                               PCI_DMA_TODEVICE);
+                       enic_queue_wq_desc_cont(wq, skb,
+                               dma_addr,
+                               len,
+                               (len_left == 0) &&
+                               (len == frag_len_left));        /* EOP? */
+                       frag_len_left -= len;
+                       offset += len;
+               }
+       }
 }
 
 static inline void enic_queue_wq_skb(struct enic *enic,
@@ -648,7 +698,8 @@ static netdev_tx_t enic_hard_start_xmit(struct sk_buff *skb,
 
        spin_lock_irqsave(&enic->wq_lock[0], flags);
 
-       if (vnic_wq_desc_avail(wq) < skb_shinfo(skb)->nr_frags + 1) {
+       if (vnic_wq_desc_avail(wq) <
+           skb_shinfo(skb)->nr_frags + ENIC_DESC_MAX_SPLITS) {
                netif_stop_queue(netdev);
                /* This is a hard error, log it */
                printk(KERN_ERR PFX "%s: BUG! Tx ring full when "
@@ -659,7 +710,7 @@ static netdev_tx_t enic_hard_start_xmit(struct sk_buff *skb,
 
        enic_queue_wq_skb(enic, wq, skb);
 
-       if (vnic_wq_desc_avail(wq) < MAX_SKB_FRAGS + 1)
+       if (vnic_wq_desc_avail(wq) < MAX_SKB_FRAGS + ENIC_DESC_MAX_SPLITS)
                netif_stop_queue(netdev);
 
        spin_unlock_irqrestore(&enic->wq_lock[0], flags);