[PATCH] prism54: fix potential race in reset scheduling

NET: prism54 - fix potential race in reset scheduling

There appears to be a race in reset scheduling logic - thread
responsible for reseting the interface should clear "reset
pending" flag before restarting the queue, otherwise timeout
handler might not schedule another reset even if it is needed.

This race is mostly theoretical as far as I can see but a race
nonetheless.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/prism54/islpci_eth.c b/drivers/net/wireless/prism54/islpci_eth.c
index a8261d8454dd54edff637a164439fc213a7e822a..bfbafe99b94a31daefda7eeb5c79f6fa934bf94b 100644 (file)
--- a/drivers/net/wireless/prism54/islpci_eth.c
+++ b/drivers/net/wireless/prism54/islpci_eth.c
@@ -253,6 +253,7 @@ islpci_monitor_rx(islpci_private *priv, struct sk_buff **skb)
         * header and without the FCS. But there a is a bit that
         * indicates if the packet is corrupted :-) */
        struct rfmon_header *hdr = (struct rfmon_header *) (*skb)->data;
+
        if (hdr->flags & 0x01)
                /* This one is bad. Drop it ! */
                return -1;
@@ -464,10 +465,8 @@ islpci_eth_receive(islpci_private *priv)
                        break;
                }
                /* update the fragment address */
-               control_block->rx_data_low[index].address = cpu_to_le32((u32)
-                                                                       priv->
-                                                                       pci_map_rx_address
-                                                                       [index]);
+               control_block->rx_data_low[index].address =
+                       cpu_to_le32((u32)priv->pci_map_rx_address[index]);
                wmb();
 
                /* increment the driver read pointer */
@@ -484,10 +483,12 @@ islpci_eth_receive(islpci_private *priv)
 void
 islpci_do_reset_and_wake(void *data)
 {
-       islpci_private *priv = (islpci_private *) data;
+       islpci_private *priv = data;
+
        islpci_reset(priv, 1);
-       netif_wake_queue(priv->ndev);
        priv->reset_task_pending = 0;
+       smp_wmb();
+       netif_wake_queue(priv->ndev);
 }
 
 void
@@ -499,12 +500,14 @@ islpci_eth_tx_timeout(struct net_device *ndev)
        /* increment the transmit error counter */
        statistics->tx_errors++;
 
-       printk(KERN_WARNING "%s: tx_timeout", ndev->name);
        if (!priv->reset_task_pending) {
-               priv->reset_task_pending = 1;
-               printk(", scheduling a reset");
+               printk(KERN_WARNING
+                       "%s: tx_timeout, scheduling reset", ndev->name);
                netif_stop_queue(ndev);
+               priv->reset_task_pending = 1;
                schedule_work(&priv->reset_task);
+       } else {
+               printk(KERN_WARNING
+                       "%s: tx_timeout, waiting for reset", ndev->name);
        }
-       printk("\n");
 }