Merge branch 'netdev_unregister_races'
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 381c759d9916 ("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>
diff --git a/net/core/dev.c b/net/core/dev.c
index 1e57efd..a8e4dd4 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3448,6 +3448,8 @@
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 @@
goto enqueue;
}
+drop:
sd->dropped++;
rps_unlock(sd);
@@ -3771,8 +3774,6 @@
pt_prev = NULL;
- rcu_read_lock();
-
another_round:
skb->skb_iif = skb->dev->ifindex;
@@ -3782,7 +3783,7 @@
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 @@
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 @@
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 @@
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 @@
ret = NET_RX_DROP;
}
-unlock:
- rcu_read_unlock();
+out:
return ret;
}
@@ -3931,29 +3931,30 @@
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 @@
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 @@
unlist_netdevice(dev);
dev->reg_state = NETREG_UNREGISTERING;
+ on_each_cpu(flush_backlog, dev, 1);
}
synchronize_net();
@@ -6770,8 +6774,6 @@
dev->reg_state = NETREG_UNREGISTERED;
- on_each_cpu(flush_backlog, dev, 1);
-
netdev_wait_allrefs(dev);
/* paranoia */