From: Eric Dumazet <eric.dumazet@gmail.com>
To: Shlomo Pongartz <shlomop@mellanox.com>
Cc: netdev@vger.kernel.org
Subject: Re: ndo_get_stats and rtnl_netlink
Date: Mon, 10 Sep 2012 11:09:49 +0200 [thread overview]
Message-ID: <1347268189.1234.1301.camel@edumazet-glaptop> (raw)
In-Reply-To: <504CB464.6010207@mellanox.com>
On Sun, 2012-09-09 at 18:23 +0300, Shlomo Pongartz wrote:
> Hi,
>
> Just realized that dev_get_stats which calls into a netdevice
> ndo_get_stats64/ndo_get_stats can be
> called with or without RTNL lock protection. If called from
> rtnl_fill_ifinfo e.g as of invocation of
> "ip link show <interface>, there IS locking, however if called from
> dev_seq_printf_stats e.g as of
> invocation of reading the /sys/class/net/<interface>/statistics/
> entries, etc more cases -- no locking.
>
> This turned to be problematic when implementing the ethtool
> "set_channels" directive which
> changes the number of **rings**, since we stepped on a bug where the
> rings data structure was
> changed by the ethtool flow in the same time a statistics call was done
> into the driver, etc.
>
> What would be the way to continue here, per driver lock sounds non
> generic...
RTNL locking is not needed to fetch stats, and would be overkill.
Each driver has its own way to protect/gather its stats.
next prev parent reply other threads:[~2012-09-10 9:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-09 15:23 ndo_get_stats and rtnl_netlink Shlomo Pongartz
2012-09-10 9:09 ` Eric Dumazet [this message]
2012-09-10 19:10 ` Or Gerlitz
2012-09-10 19:15 ` Eric Dumazet
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