netdev - Re: [PATCH net-next 16/16] sfc: Don't receive packets when the napi budget == 0

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Message-Id: <20140315.122912.1621610280186900725.davem@davemloft.net>
Date:	Sat, 15 Mar 2014 12:29:12 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	ben@...adent.org.uk
Cc:	ebiederm@...ssion.com, eric.dumazet@...il.com,
	netdev@...r.kernel.org, xiyou.wangcong@...il.com, mpm@...enic.com,
	satyam.sharma@...il.com
Subject: Re: [PATCH net-next 16/16] sfc: Don't receive packets when the
 napi budget == 0

From: Ben Hutchings <ben@...adent.org.uk>
Date: Sat, 15 Mar 2014 15:23:34 +0000

> On Fri, 2014-03-14 at 18:11 -0700, Eric W. Biederman wrote:
>> Processing any incoming packets with a with a napi budget of 0
>> is incorrect driver behavior.
>> 
>> This matters as netpoll will shortly call drivers with a budget of 0
>> to avoid receive packet processing happening in hard irq context.
> 
> But this also prevents handling TX completions, at which point you may
> as well change efx_netpoll() to a no-op.  And then, does it make sense
> to implement ndo_poll_controller at all?
> 
> Note that sfc does have a module parameter to enable separate RX and TX
> completions so they could be polled separately, but it is disabled by
> default.

TX completions should run unconditionally, irregardless of the given
budget.

This is how I have coded all of my drivers, and I how I tell others
to do so.
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