netdev - Re: [PATCH net v2] net: pktgen: fix pkt

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Message-Id: <20161003.013028.1884210069858462849.davem@davemloft.net>
Date:   Mon, 03 Oct 2016 01:30:28 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     pabeni@...hat.com
Cc:     netdev@...r.kernel.org, bogdan.hamciuc@...escale.com,
        greearb@...delatech.com, sergei.shtylyov@...entembedded.com
Subject: Re: [PATCH net v2] net: pktgen: fix pkt_size

From: Paolo Abeni <pabeni@...hat.com>
Date: Fri, 30 Sep 2016 16:56:45 +0200

> The commit 879c7220e828 ("net: pktgen: Observe needed_headroom
> of the device") increased the 'pkt_overhead' field value by
> LL_RESERVED_SPACE.
> As a side effect the generated packet size, computed as:
> 
> 	/* Eth + IPh + UDPh + mpls */
> 	datalen = pkt_dev->cur_pkt_size - 14 - 20 - 8 -
> 		  pkt_dev->pkt_overhead;
> 
> is decreased by the same value.
> The above changed slightly the behavior of existing pktgen users,
> and made the procfs interface somewhat inconsistent.
> Fix it by restoring the previous pkt_overhead value and using
> LL_RESERVED_SPACE as extralen in skb allocation.
> Also, change pktgen_alloc_skb() to only partially reserve
> the headroom to allow the caller to prefetch from ll header
> start.
> 
> v1 -> v2:
>  - fixed some typos in the comments
> 
> Fixes: 879c7220e828 ("net: pktgen: Observe needed_headroom of the device")
> Suggested-by: Ben Greear <greearb@...delatech.com>
> Signed-off-by: Paolo Abeni <pabeni@...hat.com>

Applied and queued up for -stable.