From: David Miller <davem@davemloft.net>
To: zoltan.kiss@citrix.com
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
Subject: Re: [PATCH net] xen-netback: Fix slot estimation
Date: Thu, 05 Jun 2014 15:02:09 -0700 (PDT) [thread overview]
Message-ID: <20140605.150209.365488173138758921.davem@davemloft.net> (raw)
In-Reply-To: <1401802336-25182-1-git-send-email-zoltan.kiss@citrix.com>
From: Zoltan Kiss <zoltan.kiss@citrix.com>
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 <zoltan.kiss@citrix.com>
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.
next prev parent reply other threads:[~2014-06-05 22:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-03 13:32 [PATCH net] xen-netback: Fix slot estimation Zoltan Kiss
2014-06-03 13:37 ` Paul Durrant
2014-06-03 14:04 ` Zoltan Kiss
2014-06-03 13:52 ` David Laight
2014-06-03 20:24 ` Zoltan Kiss
2014-06-05 22:02 ` David Miller [this message]
2014-06-06 10:20 ` Zoltan Kiss
2014-06-06 20:06 ` David Miller
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