netdev - Re: [net-next PATCH 1/2] igbvf: add new driver to support 82576 virtual functions

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Date:	Wed, 18 Mar 2009 08:22:46 -0700
From:	Alexander Duyck <alexander.h.duyck@...el.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"gospo@...hat.com" <gospo@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"greg@...ah.com" <greg@...ah.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"Zhao, Yu" <yu.zhao@...el.com>
Subject: Re: [net-next PATCH 1/2] igbvf: add new driver to support 82576 virtual
 functions

Andrew Morton wrote:
> On Tue, 17 Mar 2009 17:12:48 -0700 Alexander Duyck <alexander.h.duyck@...el.com> wrote:
> 
>> Thanks for all the comments.  I tried to incorporate most of them into 
>> the igbvf driver and also ended up porting some over to our other 
>> drivers, specifically igb since the igbvf driver copies much of the code.
>>
>> I have added my comments inline below.
>>
>> Thanks,
>>
>> Alex
>>
>> Andrew Morton wrote:
>>> On Tue, 10 Mar 2009 19:09:28 -0700 Jeff Kirsher <jeffrey.t.kirsher@...el.com> wrote:
>>>
>>>> From: Alexander Duyck <alexander.h.duyck@...el.com>
>>>>
>>>> This adds an igbvf driver to handle virtual functions provided
>>>> by the igb driver.
>>> The drive-by reader is now wondering what a "virtual function" is.
> 
> ^^ this comment was missed.
> 
> I was indirectly asking for an overview (preferably in the changelog) of
> what the whole patch actually does.

Sorry, while I missed the comment in my response I had gotten to 
addressing it in the next version.  I updated it to more thoroughly 
describe what the VF driver is doing.  I also included instructions on 
how to enable the VFs from the PF so that they can be tested.

>>>> +static int igbvf_set_ringparam(struct net_device *netdev,
>>>> +                               struct ethtool_ringparam *ring)
>>>> +{
>>>> +     struct igbvf_adapter *adapter = netdev_priv(netdev);
>>>> +     struct igbvf_ring *tx_ring, *tx_old;
>>>> +     struct igbvf_ring *rx_ring, *rx_old;
>>>> +     int err;
>>>> +
>>>> +     if ((ring->rx_mini_pending) || (ring->rx_jumbo_pending))
>>>> +             return -EINVAL;
>>>> +
>>>> +     while (test_and_set_bit(__IGBVF_RESETTING, &adapter->state))
>>>> +             msleep(1);
>>> No timeout needed here?  Interrupts might not be working, for example..
>> This bit isn't set in interrupt context.  This is always used out of 
>> interrupt context and is just to prevent multiple setting changes at the 
>> same time.
> 
> Oh.  Can't use plain old mutex_lock()?

We have one or two spots that actually check to see if the bit is set 
and just report a warning instead of actually waiting on the bit to clear.

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