Attachment 185531 Details for Bug 251978 – patch example w/o additional locking

[patch] patch example w/o additional locking

net.patch (text/plain), 2.41 KB, created by Tina Yang on 2007-09-04 03:20:06 UTC

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Creator: Tina Yang

Created: 2007-09-04 03:20:06 UTC

Size: 2.41 KB

patch

obsolete

>--- linux-2.6.9/net/core/dev.c.orig     2007-06-28 00:53:51.178885000 -0700
>+++ linux-2.6.9/net/core/dev.c  2007-09-03 20:01:34.767326000 -0700
>@@ -1760,6 +1760,8 @@ static void net_rx_action(struct softirq
>        unsigned long start_time = jiffies;
>        int budget = netdev_max_backlog;
>        void *have;
>+       struct net_device *null_dev = &queue->poll_list -
>+                                      offsetof(struct net_device, poll_list);
>
>        local_irq_disable();
>
>@@ -1774,8 +1776,22 @@ static void net_rx_action(struct softirq
>                dev = list_entry(queue->poll_list.next,
>                                 struct net_device, poll_list);
>
>+               /* The last dev could have been removed by netpoll
>+                */
>+               if (dev == null_dev)
>+                       break;
>+
>                have = netpoll_poll_lock(dev);
>
>+               /* netpoll could have just released the lock,
>+                * check if dev has already been polled
>+                */
>+               if ((dev->poll_list->next != LIST_POISON1) {
>+                       netpoll_poll_unlock(have);
>+                       local_irq_disable();
>+                       continue;
>+               }
>+
>                if (dev->quota <= 0 || dev->poll(dev, &budget)) {
>                        netpoll_poll_unlock(have);
>                        local_irq_disable();
>
>
>--- linux-2.6.9/net/core/netpoll.c.orig 2007-06-28 00:53:27.847957000 -0700
>+++ linux-2.6.9/net/core/netpoll.c      2007-09-03 20:04:08.655594000 -0700
>@@ -96,13 +96,17 @@ static void poll_napi(struct net_device
>        if (test_bit(__LINK_STATE_RX_SCHED, &dev->state) &&
>            npinfo->poll_owner != smp_processor_id() &&
>            spin_trylock(&npinfo->poll_lock)) {
>-               npinfo->rx_flags |= NETPOLL_RX_DROP;
>-               atomic_inc(&trapped);
>+               /* Check if dev has already been processed
>+                */
>+               if (dev->poll_list->next != LIST_POISON1) {
>+                       npinfo->rx_flags |= NETPOLL_RX_DROP;
>+                       atomic_inc(&trapped);
>
>-               dev->poll(dev, &budget);
>+                       dev->poll(dev, &budget);
>
>-               atomic_dec(&trapped);
>-               npinfo->rx_flags &= ~NETPOLL_RX_DROP;
>+                       atomic_dec(&trapped);
>+                       npinfo->rx_flags &= ~NETPOLL_RX_DROP;
>+               }
>                spin_unlock(&npinfo->poll_lock);
>        }
> }

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