netdev - Re: [PATCH net 1/4] net/mlx4_en: fix tx

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Message-ID: <20160525211035.GA64072@ast-mbp.thefacebook.com>
Date:	Wed, 25 May 2016 14:10:37 -0700
From:	Alexei Starovoitov <alexei.starovoitov@...il.com>
To:	Eric Dumazet <edumazet@...gle.com>
Cc:	"David S . Miller" <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Willem de Bruijn <willemb@...gle.com>,
	Eugenia Emantayev <eugenia@...lanox.com>,
	Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH net 1/4] net/mlx4_en: fix tx_dropped bug

On Wed, May 25, 2016 at 09:50:36AM -0700, Eric Dumazet wrote:
> 1) mlx4_en_xmit() can increment priv->stats.tx_dropped, but this variable
> is overwritten in mlx4_en_DUMP_ETH_STATS().
> 
> 2) This increment was not SMP safe, as a port might have many TX queues.
> 
> Add a per TX ring tx_dropped to fix these issues.
> 
> This is u32 as mlx4_en_DUMP_ETH_STATS() will add a 32bit field.
> 
> So lets avoid bugs with SNMP agents having to cope with partial
> overwraps. (One of these agents being bond_fold_stats())
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: Willem de Bruijn <willemb@...gle.com>
> Cc: Eugenia Emantayev <eugenia@...lanox.com>

this problem was bugging me as well. thank you for fixing it.
Acked-by: Alexei Starovoitov <ast@...nel.org>