ieee1394: eth1394: handle tlabel exhaustion

When eth1394 was unable to acquire a transaction label, it just dropped
outgoing packets without attempt to resend them later.

The transmit queue is now halted if no tlabel is available to
->hard_start_xmit().  A workqueue job is then scheduled to catch the
moment when ieee1394 recycled the next lot of tlabels.

Fixes http://bugzilla.kernel.org/show_bug.cgi?id=8402

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

diff --git a/drivers/ieee1394/eth1394.c b/drivers/ieee1394/eth1394.c
index 8e4c959e586ae0f286fbf6940231a655db079093..d6b19c2780afcb9faa05d59f3404d29b05997180 100644 (file)
--- a/drivers/ieee1394/eth1394.c
+++ b/drivers/ieee1394/eth1394.c
@@ -47,6 +47,7 @@
 #include <linux/types.h>
 #include <linux/delay.h>
 #include <linux/init.h>
+#include <linux/workqueue.h>
 
 #include <linux/netdevice.h>
 #include <linux/inetdevice.h>
@@ -235,6 +236,9 @@ static int ether1394_open(struct net_device *dev)
 /* This is called after an "ifdown" */
 static int ether1394_stop(struct net_device *dev)
 {
+       /* flush priv->wake */
+       flush_scheduled_work();
+
        netif_stop_queue(dev);
        return 0;
 }
@@ -530,6 +534,37 @@ static void ether1394_init_dev(struct net_device *dev)
        dev->tx_queue_len       = 1000;
 }
 
+/*
+ * Wake the queue up after commonly encountered transmit failure conditions are
+ * hopefully over.  Currently only tlabel exhaustion is accounted for.
+ */
+static void ether1394_wake_queue(struct work_struct *work)
+{
+       struct eth1394_priv *priv;
+       struct hpsb_packet *packet;
+
+       priv = container_of(work, struct eth1394_priv, wake);
+       packet = hpsb_alloc_packet(0);
+
+       /* This is really bad, but unjam the queue anyway. */
+       if (!packet)
+               goto out;
+
+       packet->host = priv->host;
+       packet->node_id = priv->wake_node;
+       /*
+        * A transaction label is all we really want.  If we get one, it almost
+        * always means we can get a lot more because the ieee1394 core recycled
+        * a whole batch of tlabels, at last.
+        */
+       if (hpsb_get_tlabel(packet) == 0)
+               hpsb_free_tlabel(packet);
+
+       hpsb_free_packet(packet);
+out:
+       netif_wake_queue(priv->wake_dev);
+}
+
 /*
  * This function is called every time a card is found. It is generally called
  * when the module is installed. This is where we add all of our ethernet
@@ -574,6 +609,8 @@ static void ether1394_add_host(struct hpsb_host *host)
        spin_lock_init(&priv->lock);
        priv->host = host;
        priv->local_fifo = fifo_addr;
+       INIT_WORK(&priv->wake, ether1394_wake_queue);
+       priv->wake_dev = dev;
 
        hi = hpsb_create_hostinfo(&eth1394_highlevel, host, sizeof(*hi));
        if (hi == NULL) {
@@ -1390,22 +1427,17 @@ static int ether1394_prep_write_packet(struct hpsb_packet *p,
                                       u64 addr, void *data, int tx_len)
 {
        p->node_id = node;
-       p->data = NULL;
 
-       p->tcode = TCODE_WRITEB;
-       p->header[1] = host->node_id << 16 | addr >> 32;
-       p->header[2] = addr & 0xffffffff;
+       if (hpsb_get_tlabel(p))
+               return -EAGAIN;
 
+       p->tcode = TCODE_WRITEB;
        p->header_size = 16;
        p->expect_response = 1;
-
-       if (hpsb_get_tlabel(p)) {
-               ETH1394_PRINT_G(KERN_ERR, "Out of tlabels\n");
-               return -1;
-       }
        p->header[0] =
                p->node_id << 16 | p->tlabel << 10 | 1 << 8 | TCODE_WRITEB << 4;
-
+       p->header[1] = host->node_id << 16 | addr >> 32;
+       p->header[2] = addr & 0xffffffff;
        p->header[3] = tx_len << 16;
        p->data_size = (tx_len + 3) & ~3;
        p->data = data;
@@ -1451,7 +1483,7 @@ static int ether1394_send_packet(struct packet_task *ptask, unsigned int tx_len)
 
        packet = ether1394_alloc_common_packet(priv->host);
        if (!packet)
-               return -1;
+               return -ENOMEM;
 
        if (ptask->tx_type == ETH1394_GASP) {
                int length = tx_len + 2 * sizeof(quadlet_t);
@@ -1462,7 +1494,7 @@ static int ether1394_send_packet(struct packet_task *ptask, unsigned int tx_len)
                                               ptask->addr, ptask->skb->data,
                                               tx_len)) {
                hpsb_free_packet(packet);
-               return -1;
+               return -EAGAIN;
        }
 
        ptask->packet = packet;
@@ -1471,7 +1503,7 @@ static int ether1394_send_packet(struct packet_task *ptask, unsigned int tx_len)
 
        if (hpsb_send_packet(packet) < 0) {
                ether1394_free_packet(packet);
-               return -1;
+               return -EIO;
        }
 
        return 0;
@@ -1514,13 +1546,18 @@ static void ether1394_complete_cb(void *__ptask)
 
        ptask->outstanding_pkts--;
        if (ptask->outstanding_pkts > 0 && !fail) {
-               int tx_len;
+               int tx_len, err;
 
                /* Add the encapsulation header to the fragment */
                tx_len = ether1394_encapsulate(ptask->skb, ptask->max_payload,
                                               &ptask->hdr);
-               if (ether1394_send_packet(ptask, tx_len))
+               err = ether1394_send_packet(ptask, tx_len);
+               if (err) {
+                       if (err == -EAGAIN)
+                               ETH1394_PRINT_G(KERN_ERR, "Out of tlabels\n");
+
                        ether1394_dg_complete(ptask, 1);
+               }
        } else {
                ether1394_dg_complete(ptask, fail);
        }
@@ -1633,8 +1670,17 @@ static int ether1394_tx(struct sk_buff *skb, struct net_device *dev)
        /* Add the encapsulation header to the fragment */
        tx_len = ether1394_encapsulate(skb, max_payload, &ptask->hdr);
        dev->trans_start = jiffies;
-       if (ether1394_send_packet(ptask, tx_len))
-               goto fail;
+       if (ether1394_send_packet(ptask, tx_len)) {
+               if (dest_node == (LOCAL_BUS | ALL_NODES))
+                       goto fail;
+
+               /* Most failures of ether1394_send_packet are recoverable. */
+               netif_stop_queue(dev);
+               priv->wake_node = dest_node;
+               schedule_work(&priv->wake);
+               kmem_cache_free(packet_task_cache, ptask);
+               return NETDEV_TX_BUSY;
+       }
 
        return NETDEV_TX_OK;
 fail:

diff --git a/drivers/ieee1394/eth1394.h b/drivers/ieee1394/eth1394.h
index a3439ee7cb4ece87c1ecf8c0751ccd1f43f45f00..4f3e2dd46f0049c52211b589d2623a8053fcd9e7 100644 (file)
--- a/drivers/ieee1394/eth1394.h
+++ b/drivers/ieee1394/eth1394.h
@@ -66,6 +66,10 @@ struct eth1394_priv {
        int bc_dgl;                     /* Outgoing broadcast datagram label */
        struct list_head ip_node_list;  /* List of IP capable nodes      */
        struct unit_directory *ud_list[ALL_NODES]; /* Cached unit dir list */
+
+       struct work_struct wake;        /* Wake up after xmit failure    */
+       struct net_device *wake_dev;    /* Stupid backlink for .wake     */
+       nodeid_t wake_node;             /* Destination of failed xmit    */
 };