[NET]: Fix races in net_rx_action vs netpoll.
Keep netpoll/poll_napi from messing with the poll_list. Only net_rx_action is allowed to manipulate the list. Signed-off-by: Olaf Kirch <olaf.kirch@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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29578624e3
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@ -261,6 +261,8 @@ enum netdev_state_t
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__LINK_STATE_LINKWATCH_PENDING,
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__LINK_STATE_DORMANT,
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__LINK_STATE_QDISC_RUNNING,
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/* Set by the netpoll NAPI code */
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__LINK_STATE_POLL_LIST_FROZEN,
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};
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@ -1014,6 +1016,14 @@ static inline void netif_rx_complete(struct net_device *dev)
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{
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unsigned long flags;
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#ifdef CONFIG_NETPOLL
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/* Prevent race with netpoll - yes, this is a kludge.
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* But at least it doesn't penalize the non-netpoll
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* code path. */
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if (test_bit(__LINK_STATE_POLL_LIST_FROZEN, &dev->state))
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return;
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#endif
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local_irq_save(flags);
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__netif_rx_complete(dev);
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local_irq_restore(flags);
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@ -124,6 +124,13 @@ static void poll_napi(struct netpoll *np)
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if (test_bit(__LINK_STATE_RX_SCHED, &np->dev->state) &&
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npinfo->poll_owner != smp_processor_id() &&
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spin_trylock(&npinfo->poll_lock)) {
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/* When calling dev->poll from poll_napi, we may end up in
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* netif_rx_complete. However, only the CPU to which the
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* device was queued is allowed to remove it from poll_list.
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* Setting POLL_LIST_FROZEN tells netif_rx_complete
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* to leave the NAPI state alone.
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*/
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set_bit(__LINK_STATE_POLL_LIST_FROZEN, &np->dev->state);
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npinfo->rx_flags |= NETPOLL_RX_DROP;
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atomic_inc(&trapped);
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@ -131,6 +138,7 @@ static void poll_napi(struct netpoll *np)
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atomic_dec(&trapped);
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npinfo->rx_flags &= ~NETPOLL_RX_DROP;
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clear_bit(__LINK_STATE_POLL_LIST_FROZEN, &np->dev->state);
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spin_unlock(&npinfo->poll_lock);
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}
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}
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