netdev - Re: [PATCH net-next] neigh: increase queue_len_bytes to match wmem

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Date:   Tue, 29 Aug 2017 16:11:05 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     eric.dumazet@...il.com
Cc:     f.fainelli@...il.com, netdev@...r.kernel.org
Subject: Re: [PATCH net-next] neigh: increase queue_len_bytes to match
 wmem_default

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Tue, 29 Aug 2017 15:16:01 -0700

> From: Eric Dumazet <edumazet@...gle.com>
> 
> Florian reported UDP xmit drops that could be root caused to the
> too small neigh limit.
> 
> Current limit is 64 KB, meaning that even a single UDP socket would hit
> it, since its default sk_sndbuf comes from net.core.wmem_default
> (~212992 bytes on 64bit arches).
> 
> Once ARP/ND resolution is in progress, we should allow a little more
> packets to be queued, at least for one producer.
> 
> Once neigh arp_queue is filled, a rogue socket should hit its sk_sndbuf
> limit and either block in sendmsg() or return -EAGAIN.
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: Florian Fainelli <f.fainelli@...il.com>

Applied, thanks for following up on this.