[PATCH] powerpc/cell spidernet zlen min packet length

Polite device drivers pad short packets to 60 bytes,
so that mean-spirited users don't accidentally DOS
some other OS that can't handle short packets.

Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

diff --git a/drivers/net/spider_net.c b/drivers/net/spider_net.c
index 52bf1b2..f5f7357 100644 (file)
--- a/drivers/net/spider_net.c
+++ b/drivers/net/spider_net.c
@@ -648,18 +648,26 @@ spider_net_prepare_tx_descr(struct spider_net_card *card,
 {
        struct spider_net_descr *descr = card->tx_chain.head;
        dma_addr_t buf;
+       int length;
 
-       buf = pci_map_single(card->pdev, skb->data, skb->len, PCI_DMA_TODEVICE);
+       length = skb->len;
+       if (length < ETH_ZLEN) {
+               if (skb_pad(skb, ETH_ZLEN-length))
+                       return 0;
+               length = ETH_ZLEN;
+       }
+
+       buf = pci_map_single(card->pdev, skb->data, length, PCI_DMA_TODEVICE);
        if (pci_dma_mapping_error(buf)) {
                if (netif_msg_tx_err(card) && net_ratelimit())
                        pr_err("could not iommu-map packet (%p, %i). "
-                                 "Dropping packet\n", skb->data, skb->len);
+                                 "Dropping packet\n", skb->data, length);
                card->spider_stats.tx_iommu_map_error++;
                return -ENOMEM;
        }
 
        descr->buf_addr = buf;
-       descr->buf_size = skb->len;
+       descr->buf_size = length;
        descr->next_descr_addr = 0;
        descr->skb = skb;
        descr->data_status = 0;
@@ -693,6 +701,7 @@ spider_net_release_tx_descr(struct spider_net_card *card)
 {
        struct spider_net_descr *descr = card->tx_chain.tail;
        struct sk_buff *skb;
+       unsigned int len;
 
        card->tx_chain.tail = card->tx_chain.tail->next;
        descr->dmac_cmd_status |= SPIDER_NET_DESCR_NOT_IN_USE;
@@ -701,7 +710,8 @@ spider_net_release_tx_descr(struct spider_net_card *card)
        skb = descr->skb;
        if (!skb)
                return;
-       pci_unmap_single(card->pdev, descr->buf_addr, skb->len,
+       len = skb->len < ETH_ZLEN ? ETH_ZLEN : skb->len;
+       pci_unmap_single(card->pdev, descr->buf_addr, len,
                        PCI_DMA_TODEVICE);
        dev_kfree_skb_any(skb);
 }