netdev - Re: [PATCH net-next 2/2] tg3: Fix for tg3 transmit queue 0 timed out when too many gso

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Message-ID: <1453351014.1223.353.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Wed, 20 Jan 2016 20:36:54 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	skallam <siva.kallam@...adcom.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org, mchan@...adcom.com,
	prashant@...adcom.com
Subject: Re: [PATCH net-next 2/2] tg3: Fix for tg3 transmit queue 0 timed
 out when too many gso_segs.

On Wed, 2016-01-20 at 17:16 +0530, skallam wrote:
> From: Siva Reddy Kallam <siva.kallam@...adcom.com>
> 
> There is an issue on the GSO path inside tg3_tso_bug() when we don't
> have sufficient descriptors available, we stop the queue. This queue
> may never get started again as there are no Tx completions pending.
> 
> For example if the tcp segment size is as low as 88 bytes and TSO packet
> from the stack is quite big(<64 K), gso_segs exceeds the limit of
> descriptors available.
> 
> tg3_tso_bug_gso_check() is implemented to verify if the total no. of
> descriptors available for gso are sufficient or not. If not sufficient
> we simply linearize the the skb and transmit it once again or drop the
> skb.

I find this changelog misleading.

linearize wont change gso_segs

You are in fact segmenting the GSO packet, which is very different than
linearizing it.