netdev - Re: Regression: [PATCH] mlx4: give precise rx/tx bytes/packets counters

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Message-ID: <1480613764.18162.324.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Thu, 01 Dec 2016 09:36:04 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Saeed Mahameed <saeedm@....mellanox.co.il>
Cc:     Jesper Dangaard Brouer <brouer@...hat.com>,
        David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Tariq Toukan <tariqt@...lanox.com>
Subject: Re: Regression: [PATCH] mlx4: give precise rx/tx bytes/packets
 counters

On Thu, 2016-12-01 at 08:08 -0800, Eric Dumazet wrote:
> On Thu, 2016-12-01 at 07:55 -0800, Eric Dumazet wrote:
> 
> > So removing the spinlock is doable, but needs to add a new parameter
> > to mlx4_en_fold_software_stats() and call netdev_stats_to_stats64()
> > before mlx4_en_fold_software_stats(dev)
> 
> Untested patch would be :
> 
>  drivers/net/ethernet/mellanox/mlx4/en_ethtool.c |    2 -
>  drivers/net/ethernet/mellanox/mlx4/en_netdev.c  |   10 +----
>  drivers/net/ethernet/mellanox/mlx4/en_port.c    |   24 +++++++++-----
>  drivers/net/ethernet/mellanox/mlx4/mlx4_en.h    |    3 +
>  4 files changed, 23 insertions(+), 16 deletions(-)

The patch is wrong, since priv->port_up could change to false while we
are running and using the about to be deleted tx/rx rings.

So the only safe thing to do is to remove the _bh suffix.

Not worth trying to avoid taking a spinlock in this code.