From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net] xen-netback: Fix slot estimation Date: Thu, 05 Jun 2014 15:02:09 -0700 (PDT) Message-ID: <20140605.150209.365488173138758921.davem@davemloft.net> References: <1401802336-25182-1-git-send-email-zoltan.kiss@citrix.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: xen-devel@lists.xenproject.org, ian.campbell@citrix.com, wei.liu2@citrix.com, paul.durrant@citrix.com, linux@eikelenboom.it, netdev@vger.kernel.org, david.vrabel@citrix.com To: zoltan.kiss@citrix.com Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:51245 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752013AbaFEWCL (ORCPT ); Thu, 5 Jun 2014 18:02:11 -0400 In-Reply-To: <1401802336-25182-1-git-send-email-zoltan.kiss@citrix.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Zoltan Kiss Date: Tue, 3 Jun 2014 14:32:16 +0100 > A recent commit (a02eb4 "xen-netback: worse-case estimate in xenvif_rx_action is > underestimating") capped the slot estimation to MAX_SKB_FRAGS, but that triggers > the next BUG_ON a few lines down, as the packet consumes more slots than > estimated. > This patch remove that cap, and if the frontend doesn't provide enough slot, > put back the skb to the top of the queue and caps rx_last_skb_slots. When the > next try also fails, it drops the packet. > Capping rx_last_skb_slots is needed because if the frontend never gives enough > slots, the ring gets stalled. > > Signed-off-by: Zoltan Kiss Like David Laight, I do not like this patch at all. Yes a crash or BUG_ON triggered is bad, but fixing it by deadlocking TCP connections (a silent failure) is not an improvement. I'm not applying this, sorry.