netdev - Re: [PATCH net] strparser: Remove early eaten to fix full tcp receive buffer stall

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Message-Id: <20180628.214316.1810821427583973651.davem@davemloft.net>
Date:   Thu, 28 Jun 2018 21:43:16 +0900 (KST)
From:   David Miller <davem@...emloft.net>
To:     doronrk@...com
Cc:     davejwatson@...com, tom@...ntonium.net, netdev@...r.kernel.org
Subject: Re: [PATCH net] strparser: Remove early eaten to fix full tcp
 receive buffer stall

From: Doron Roberts-Kedes <doronrk@...com>
Date: Tue, 26 Jun 2018 18:33:33 -0700

> On receving an incomplete message, the existing code stores the
> remaining length of the cloned skb in the early_eaten field instead of
> incrementing the value returned by __strp_recv. This defers invocation
> of sock_rfree for the current skb until the next invocation of
> __strp_recv, which returns early_eaten if early_eaten is non-zero.
> 
> This behavior causes a stall when the current message occupies the very
> tail end of a massive skb, and strp_peek/need_bytes indicates that the
> remainder of the current message has yet to arrive on the socket. The
> TCP receive buffer is totally full, causing the TCP window to go to
> zero, so the remainder of the message will never arrive.
> 
> Incrementing the value returned by __strp_recv by the amount otherwise
> stored in early_eaten prevents stalls of this nature.
> 
> Signed-off-by: Doron Roberts-Kedes <doronrk@...com>

Applied and queued up for -stable.