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Merge branch 'netdev_unregister_races'

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Julian Anastasov says:

====================
net: fixes for device unregistration

Test script from Eric W. Biederman can catch a problem
where packets from backlog are processed long after the last
synchronize_net call. This can be reproduced after few tests
if commit 381c759d99 ("ipv4: Avoid crashing in ip_error")
is reverted for the test. Incoming packets do not hold
reference to device but even if they do, subsystems do not
expect packets to fly during and after the NETDEV_UNREGISTER
event.

The first fix has the cost of netif_running check in fast path.
The second fix calls rcu_read_lock while local IRQ is disabled,
I hope this is not against the rules.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2015-07-10 18:16:37 -07:00
commit 7234e03019
1 changed files with 20 additions and 18 deletions
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38
net/core/dev.c
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@ -3448,6 +3448,8 @@ static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
local_irq_save(flags);
rps_lock(sd);
if (!netif_running(skb->dev))
goto drop;
qlen = skb_queue_len(&sd->input_pkt_queue);
if (qlen <= netdev_max_backlog && !skb_flow_limit(skb, qlen)) {
if (qlen) {
@ -3469,6 +3471,7 @@ static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
goto enqueue;
}
drop:
sd->dropped++;
rps_unlock(sd);
@ -3771,8 +3774,6 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
pt_prev = NULL;
rcu_read_lock();
another_round:
skb->skb_iif = skb->dev->ifindex;
@ -3782,7 +3783,7 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
skb->protocol == cpu_to_be16(ETH_P_8021AD)) {
skb = skb_vlan_untag(skb);
if (unlikely(!skb))
goto unlock;
goto out;
}
#ifdef CONFIG_NET_CLS_ACT
@ -3812,10 +3813,10 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
if (static_key_false(&ingress_needed)) {
skb = handle_ing(skb, &pt_prev, &ret, orig_dev);
if (!skb)
goto unlock;
goto out;
if (nf_ingress(skb, &pt_prev, &ret, orig_dev) < 0)
goto unlock;
goto out;
}
#endif
#ifdef CONFIG_NET_CLS_ACT
@ -3833,7 +3834,7 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
if (vlan_do_receive(&skb))
goto another_round;
else if (unlikely(!skb))
goto unlock;
goto out;
}
rx_handler = rcu_dereference(skb->dev->rx_handler);
@ -3845,7 +3846,7 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
switch (rx_handler(&skb)) {
case RX_HANDLER_CONSUMED:
ret = NET_RX_SUCCESS;
goto unlock;
goto out;
case RX_HANDLER_ANOTHER:
goto another_round;
case RX_HANDLER_EXACT:
@ -3899,8 +3900,7 @@ static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)
ret = NET_RX_DROP;
}
unlock:
rcu_read_unlock();
out:
return ret;
}
@ -3931,29 +3931,30 @@ static int __netif_receive_skb(struct sk_buff *skb)
static int netif_receive_skb_internal(struct sk_buff *skb)
{
int ret;
net_timestamp_check(netdev_tstamp_prequeue, skb);
if (skb_defer_rx_timestamp(skb))
return NET_RX_SUCCESS;
rcu_read_lock();
#ifdef CONFIG_RPS
if (static_key_false(&rps_needed)) {
struct rps_dev_flow voidflow, *rflow = &voidflow;
int cpu, ret;
rcu_read_lock();
cpu = get_rps_cpu(skb->dev, skb, &rflow);
int cpu = get_rps_cpu(skb->dev, skb, &rflow);
if (cpu >= 0) {
ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
rcu_read_unlock();
return ret;
}
rcu_read_unlock();
}
#endif
return __netif_receive_skb(skb);
ret = __netif_receive_skb(skb);
rcu_read_unlock();
return ret;
}
/**
@ -4498,8 +4499,10 @@ static int process_backlog(struct napi_struct *napi, int quota)
struct sk_buff *skb;
while ((skb = __skb_dequeue(&sd->process_queue))) {
rcu_read_lock();
local_irq_enable();
__netif_receive_skb(skb);
rcu_read_unlock();
local_irq_disable();
input_queue_head_incr(sd);
if (++work >= quota) {
@ -6135,6 +6138,7 @@ static void rollback_registered_many(struct list_head *head)
unlist_netdevice(dev);
dev->reg_state = NETREG_UNREGISTERING;
on_each_cpu(flush_backlog, dev, 1);
}
synchronize_net();
@ -6770,8 +6774,6 @@ void netdev_run_todo(void)
dev->reg_state = NETREG_UNREGISTERED;
on_each_cpu(flush_backlog, dev, 1);
netdev_wait_allrefs(dev);
/* paranoia */