netdev - Re: ICMP packets - ll_temac with Microblaze

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Date:	Wed, 21 Dec 2011 12:03:06 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	monstr@...str.eu
Cc:	David Miller <davem@...emloft.net>,
	John Williams <john.williams@...alogix.com>,
	netdev@...r.kernel.org
Subject: Re: ICMP packets - ll_temac with Microblaze

Le mercredi 21 décembre 2011 à 11:45 +0100, Eric Dumazet a écrit :
> Le mercredi 21 décembre 2011 à 11:41 +0100, Michal Simek a écrit :
> 
> > yes, page size is 4k.
> > 
> > Here is the log for allocation - origin size for MTU 9000 is 0x2420(9248) and size after
> > overhead is 0x3f40(16192)
> > 
> > kmalloc_node_track_caller size 00002420, SKB_WITH_OVERHEAD(ksize(data)) 00003f40
> > skb->head     c7870000
> > skb->data     c7870000
> > skb->tail     c7870000
> > skb->truesize 000040c0
> > skb->end      c7873f40
> > 
> 
> So basically truesize is bigger than previous kernel, and you hit a
> socket limit.  (RCVBUF ?)
> 
> truesize is more correct, so we uncover prior bugs.
> 
> We should allow at least one packet, regardless of its size :(
> 
> 

I would try the following patch :

diff --git a/include/net/sock.h b/include/net/sock.h
index bf6b9fd..21bb3b5 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -662,12 +662,14 @@ static inline void __sk_add_backlog(struct sock *sk, struct sk_buff *skb)
 
 /*
  * Take into account size of receive queue and backlog queue
+ * Do not take into account this skb truesize,
+ * to allow even a single big packet to come.
  */
 static inline bool sk_rcvqueues_full(const struct sock *sk, const struct sk_buff *skb)
 {
 	unsigned int qsize = sk->sk_backlog.len + atomic_read(&sk->sk_rmem_alloc);
 
-	return qsize + skb->truesize > sk->sk_rcvbuf;
+	return qsize > sk->sk_rcvbuf;
 }
 
 /* The per-socket spinlock must be held here. */


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