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net: enqueue_to_backlog() change vs not running device

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If the device attached to the packet given to enqueue_to_backlog()
is not running, we drop the packet.

But we accidentally increase sd->dropped, giving false signals
to admins: sd->dropped should be reserved to cpu backlog pressure,
not to temporary glitches at device dismantles.

While we are at it, perform the netif_running() test before
we get the rps lock, and use REASON_DEV_READY
drop reason instead of NOT_SPECIFIED.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2024-03-29 15:42:20 +00:00 committed by David S. Miller
parent 2fe50a4d72
commit 95e48d862a
1 changed files with 5 additions and 4 deletions
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9
net/core/dev.c
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@ -4801,12 +4801,13 @@ static int enqueue_to_backlog(struct sk_buff *skb, int cpu,
unsigned long flags;
unsigned int qlen;
reason = SKB_DROP_REASON_NOT_SPECIFIED;
reason = SKB_DROP_REASON_DEV_READY;
if (!netif_running(skb->dev))
goto bad_dev;
sd = &per_cpu(softnet_data, cpu);
backlog_lock_irq_save(sd, &flags);
if (!netif_running(skb->dev))
goto drop;
qlen = skb_queue_len(&sd->input_pkt_queue);
if (qlen <= READ_ONCE(net_hotdata.max_backlog) &&
!skb_flow_limit(skb, qlen)) {
@ -4827,10 +4828,10 @@ enqueue:
}
reason = SKB_DROP_REASON_CPU_BACKLOG;
drop:
sd->dropped++;
backlog_unlock_irq_restore(sd, &flags);
bad_dev:
dev_core_stats_rx_dropped_inc(skb->dev);
kfree_skb_reason(skb, reason);
return NET_RX_DROP;