netdev - Re: [RFC net-next 1/2] net: net-porcfs: Reduce rcu lock critical section

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Message-ID: <4cc44e85-cb5e-502c-30f3-c6ea564fe9ac@gmail.com>
Date:   Mon, 16 Apr 2018 14:07:07 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Saeed Mahameed <saeedm@...lanox.com>,
        "eric.dumazet@...il.com" <eric.dumazet@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>
Cc:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [RFC net-next 1/2] net: net-porcfs: Reduce rcu lock critical
 section

On 04/16/2018 01:50 PM, Saeed Mahameed wrote:
> 
> Dave, Eric, I would like to know whether it is ok to have this change
> in the kernel (make get_stats ndo "might sleep")? I really didn't get
> any convincing feedback to not do this change.

Fact that you were not convinced does not mean you were right.

I would rather not change the current behavior and risk nasty bugs.

Having SNMP daemons blocked while some device is sleeping in its ndo_get_stats()
is concerning, since it is currently an immediate operation.

ethtool -S can definitely sleep if you need fancy stats.