From: Nikolay Aleksandrov <nikolay@cumulusnetworks•com>
To: Eric Dumazet <eric.dumazet@gmail•com>,
David Miller <davem@davemloft•net>
Cc: netdev <netdev@vger•kernel.org>,
Andy Gospodarek <gospo@cumulusnetworks•com>,
Jay Vosburgh <j.vosburgh@gmail•com>,
Veaceslav Falico <vfalico@gmail•com>
Subject: Re: [PATCH net] bonding: fix bond_get_stats()
Date: Fri, 18 Mar 2016 12:26:44 +0100 [thread overview]
Message-ID: <56EBE5F4.6020003@cumulusnetworks.com> (raw)
In-Reply-To: <1458260616.31963.14.camel@edumazet-glaptop3.roam.corp.google.com>
On 03/18/2016 01:23 AM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google•com>
>
> bond_get_stats() can be called from rtnetlink (with RTNL held)
> or from /proc/net/dev seq handler (with RCU held)
>
> The logic added in commit 5f0c5f73e5ef ("bonding: make global bonding
> stats more reliable") kind of assumed only one cpu could run there.
>
> If multiple threads are reading /proc/net/dev, stats can be really
> messed up after a while.
>
> A second problem is that some fields are 32bit, so we need to properly
> handle the wrap around problem.
>
> Given that RTNL is not always held, we need to use
> bond_for_each_slave_rcu().
>
> Fixes: 5f0c5f73e5ef ("bonding: make global bonding stats more reliable")
> Signed-off-by: Eric Dumazet <edumazet@google•com>
> Cc: Andy Gospodarek <gospo@cumulusnetworks•com>
> Cc: Jay Vosburgh <j.vosburgh@gmail•com>
> Cc: Veaceslav Falico <vfalico@gmail•com>
> ---
> drivers/net/bonding/bond_main.c | 66 +++++++++++++++---------------
> include/net/bonding.h | 1
> 2 files changed, 36 insertions(+), 31 deletions(-)
>
Good catches! And the dev_get_stats() in bond_enslave is fine because the slave
is not yet linked thus can't collide with reading/updating the stats via procfs.
Reviewed-by: Nikolay Aleksandrov <nikolay@cumulusnetworks•com>
next prev parent reply other threads:[~2016-03-18 11:26 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-18 0:23 [PATCH net] bonding: fix bond_get_stats() Eric Dumazet
2016-03-18 11:26 ` Nikolay Aleksandrov [this message]
2016-03-19 3:15 ` David Miller
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