Re: [PATCH] tcp: fix retransmit of partially acked frames

From: David Miller
Date: Wed Apr 18 2012 - 16:54:14 EST

From: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Date: Wed, 18 Apr 2012 22:14:23 +0200

> From: Eric Dumazet <edumazet@xxxxxxxxxx>
> Alexander Beregalov reported skb_over_panic errors and provided stack
> trace.
> I occurs commit a21d45726aca (tcp: avoid order-1 allocations on wifi and
> tx path) added a regression, when a retransmit is done after a partial
> ACK.
> tcp_retransmit_skb() tries to aggregate several frames if the first one
> has enough available room to hold the following ones payload. This is
> controlled by /proc/sys/net/ipv4/tcp_retrans_collapse tunable (default :
> enabled)
> Problem is we must make sure _pskb_trim_head() doesnt fool
> skb_availroom() when pulling some bytes from skb (this pull is done when
> receiver ACK part of the frame).
> Reported-by: Alexander Beregalov <a.beregalov@xxxxxxxxx>
> Cc: Marc MERLIN <marc@xxxxxxxxxxx>
> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>

Applied, thanks.
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