Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=48544cc267da96a85e4d38aa1999a011229948d6
Commit:     48544cc267da96a85e4d38aa1999a011229948d6
Parent:     ea6992aa1f6ed514fe450f46befa56d8d2b6a7fb
Author:     Masakazu Mokuno <[EMAIL PROTECTED]>
AuthorDate: Fri Jul 20 17:24:56 2007 +0900
Committer:  Jeff Garzik <[EMAIL PROTECTED]>
CommitDate: Tue Jul 24 16:28:39 2007 -0400

    ps3: tx descriptor handling cleanup
    
    gelic: TX descriptor handling cleanup
    
            - Emitted return value of NETDEV_TX_LOCKED when DMA map or kick
              failure.
              Now it would free the skb, update drop packet statistics
              and return OK. Requested from Jeff Garzik.
            - Enable tx queue if number of free descriptors are more than 2
            - Fixed descriptor leak if dma map for second descriptor failed
            - Stopped calling xmit handler from interrupt handler in order
              to recheck tx queue.  Instead, call appropriate helper functions.
    
    Signed-off-by: Masakazu Mokuno <[EMAIL PROTECTED]>
    Signed-off-by: Jeff Garzik <[EMAIL PROTECTED]>
---
 drivers/net/ps3_gelic_net.c |  124 ++++++++++++++++++++++++------------------
 1 files changed, 71 insertions(+), 53 deletions(-)

diff --git a/drivers/net/ps3_gelic_net.c b/drivers/net/ps3_gelic_net.c
index f0610fb..143d7bd 100644
--- a/drivers/net/ps3_gelic_net.c
+++ b/drivers/net/ps3_gelic_net.c
@@ -408,22 +408,25 @@ static void gelic_net_release_tx_chain(struct 
gelic_net_card *card, int stop)
                        break;
 
                case GELIC_NET_DESCR_COMPLETE:
-                       card->netdev_stats.tx_packets++;
-                       card->netdev_stats.tx_bytes +=
-                               tx_chain->tail->skb->len;
+                       if (tx_chain->tail->skb) {
+                               card->netdev_stats.tx_packets++;
+                               card->netdev_stats.tx_bytes +=
+                                       tx_chain->tail->skb->len;
+                       }
                        break;
 
                case GELIC_NET_DESCR_CARDOWNED:
                        /* pending tx request */
                default:
                        /* any other value (== GELIC_NET_DESCR_NOT_IN_USE) */
-                       goto out;
+                       if (!stop)
+                               goto out;
                }
                gelic_net_release_tx_descr(card, tx_chain->tail);
-               release = 1;
+               release ++;
        }
 out:
-       if (!stop && release)
+       if (!stop && (2 < release))
                netif_wake_queue(card->netdev);
 }
 
@@ -660,19 +663,21 @@ static int gelic_net_prepare_tx_descr_v(struct 
gelic_net_card *card,
 {
        dma_addr_t buf[2];
        unsigned int vlan_len;
+       struct gelic_net_descr *sec_descr = descr->next;
 
        if (skb->len < GELIC_NET_VLAN_POS)
                return -EINVAL;
 
-       memcpy(&descr->vlan, skb->data, GELIC_NET_VLAN_POS);
+       vlan_len = GELIC_NET_VLAN_POS;
+       memcpy(&descr->vlan, skb->data, vlan_len);
        if (card->vlan_index != -1) {
+               /* internal vlan tag used */
                descr->vlan.h_vlan_proto = htons(ETH_P_8021Q); /* vlan 0x8100*/
                descr->vlan.h_vlan_TCI = htons(card->vlan_id[card->vlan_index]);
-               vlan_len = GELIC_NET_VLAN_POS + VLAN_HLEN; /* VLAN_HLEN=4 */
-       } else
-               vlan_len = GELIC_NET_VLAN_POS; /* no vlan tag */
+               vlan_len += VLAN_HLEN; /* added for above two lines */
+       }
 
-       /* first descr */
+       /* map data area */
        buf[0] = dma_map_single(ctodev(card), &descr->vlan,
                             vlan_len, DMA_TO_DEVICE);
 
@@ -683,20 +688,6 @@ static int gelic_net_prepare_tx_descr_v(struct 
gelic_net_card *card,
                return -ENOMEM;
        }
 
-       descr->buf_addr = buf[0];
-       descr->buf_size = vlan_len;
-       descr->skb = skb; /* not used */
-       descr->data_status = 0;
-       gelic_net_set_txdescr_cmdstat(descr, skb, 1); /* not the frame end */
-
-       /* second descr */
-       card->tx_chain.head = card->tx_chain.head->next;
-       descr->next_descr_addr = descr->next->bus_addr;
-       descr = descr->next;
-       if (gelic_net_get_descr_status(descr) != GELIC_NET_DESCR_NOT_IN_USE)
-               /* XXX will be removed */
-               dev_err(ctodev(card), "descr is not free!\n");
-
        buf[1] = dma_map_single(ctodev(card), skb->data + GELIC_NET_VLAN_POS,
                             skb->len - GELIC_NET_VLAN_POS,
                             DMA_TO_DEVICE);
@@ -711,13 +702,24 @@ static int gelic_net_prepare_tx_descr_v(struct 
gelic_net_card *card,
                return -ENOMEM;
        }
 
-       descr->buf_addr = buf[1];
-       descr->buf_size = skb->len - GELIC_NET_VLAN_POS;
-       descr->skb = skb;
+       /* first descr */
+       descr->buf_addr = buf[0];
+       descr->buf_size = vlan_len;
+       descr->skb = NULL; /* not used */
        descr->data_status = 0;
-       descr->next_descr_addr = 0; /* terminate hw descr */
-       gelic_net_set_txdescr_cmdstat(descr, skb, 0);
+       descr->next_descr_addr = descr->next->bus_addr;
+       gelic_net_set_txdescr_cmdstat(descr, skb, 1); /* not the frame end */
 
+       /* second descr */
+       sec_descr->buf_addr = buf[1];
+       sec_descr->buf_size = skb->len - GELIC_NET_VLAN_POS;
+       sec_descr->skb = skb;
+       sec_descr->data_status = 0;
+       sec_descr->next_descr_addr = 0; /* terminate hw descr */
+       gelic_net_set_txdescr_cmdstat(sec_descr, skb, 0);
+
+       /* bump free descriptor pointer */
+       card->tx_chain.head = sec_descr->next;
        return 0;
 }
 
@@ -730,7 +732,7 @@ static int gelic_net_prepare_tx_descr_v(struct 
gelic_net_card *card,
 static int gelic_net_kick_txdma(struct gelic_net_card *card,
                                struct gelic_net_descr *descr)
 {
-       int status = -ENXIO;
+       int status = 0;
        int count = 10;
 
        if (card->tx_dma_progress)
@@ -764,47 +766,62 @@ static int gelic_net_kick_txdma(struct gelic_net_card 
*card,
 static int gelic_net_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
        struct gelic_net_card *card = netdev_priv(netdev);
-       struct gelic_net_descr *descr = NULL;
+       struct gelic_net_descr *descr;
        int result;
        unsigned long flags;
 
        spin_lock_irqsave(&card->tx_dma_lock, flags);
 
        gelic_net_release_tx_chain(card, 0);
-       if (!skb)
-               goto kick;
+
        descr = gelic_net_get_next_tx_descr(card);
        if (!descr) {
+               /*
+                * no more descriptors free
+                */
                netif_stop_queue(netdev);
                spin_unlock_irqrestore(&card->tx_dma_lock, flags);
                return NETDEV_TX_BUSY;
        }
-       result = gelic_net_prepare_tx_descr_v(card, descr, skb);
-
-       if (result)
-               goto error;
-
-       card->tx_chain.head = card->tx_chain.head->next;
 
-       if (descr->prev)
-               descr->prev->next_descr_addr = descr->bus_addr;
-kick:
+       result = gelic_net_prepare_tx_descr_v(card, descr, skb);
+       if (result) {
+               /*
+                * DMA map failed.  As chanses are that failure
+                * would continue, just release skb and return
+                */
+               card->netdev_stats.tx_dropped++;
+               dev_kfree_skb_any(skb);
+               spin_unlock_irqrestore(&card->tx_dma_lock, flags);
+               return NETDEV_TX_OK;
+       }
+       /*
+        * link this prepared descriptor to previous one
+        * to achieve high performance
+        */
+       descr->prev->next_descr_addr = descr->bus_addr;
        /*
         * as hardware descriptor is modified in the above lines,
         * ensure that the hardware sees it
         */
        wmb();
-       if (gelic_net_kick_txdma(card, card->tx_chain.tail))
-               goto error;
+       if (gelic_net_kick_txdma(card, descr)) {
+               /*
+                * kick failed.
+                * release descriptors which were just prepared
+                */
+               card->netdev_stats.tx_dropped++;
+               gelic_net_release_tx_descr(card, descr);
+               gelic_net_release_tx_descr(card, descr->next);
+               card->tx_chain.tail = descr->next->next;
+               dev_info(ctodev(card), "%s: kick failure\n", __func__);
+       } else {
+               /* OK, DMA started/reserved */
+               netdev->trans_start = jiffies;
+       }
 
-       netdev->trans_start = jiffies;
        spin_unlock_irqrestore(&card->tx_dma_lock, flags);
        return NETDEV_TX_OK;
-
-error:
-       card->netdev_stats.tx_dropped++;
-       spin_unlock_irqrestore(&card->tx_dma_lock, flags);
-       return NETDEV_TX_LOCKED;
 }
 
 /**
@@ -1025,9 +1042,10 @@ static irqreturn_t gelic_net_interrupt(int irq, void 
*ptr)
        if (status & GELIC_NET_TXINT) {
                spin_lock_irqsave(&card->tx_dma_lock, flags);
                card->tx_dma_progress = 0;
+               gelic_net_release_tx_chain(card, 0);
+               /* kick outstanding tx descriptor if any */
+               gelic_net_kick_txdma(card, card->tx_chain.tail);
                spin_unlock_irqrestore(&card->tx_dma_lock, flags);
-               /* start pending DMA */
-               gelic_net_xmit(NULL, netdev);
        }
        return IRQ_HANDLED;
 }
-
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