netdev - Re: [PATCH v2 net-next] r8169: Add values missing in @get

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Message-ID: <20150824102935.GM19683@calimero.vinschen.de>
Date:	Mon, 24 Aug 2015 12:29:35 +0200
From:	Corinna Vinschen <vinschen@...hat.com>
To:	Francois Romieu <romieu@...zoreil.com>, netdev@...r.kernel.org,
	Hayes Wang <hayeswang@...ltek.com>,
	Ivan Vecera <ivecera@...hat.com>,
	David Miller <davem@...emloft.net>,
	nic_swsd <nic_swsd@...ltek.com>
Subject: Re: [PATCH v2 net-next] r8169: Add values missing in @get_stats64
 from HW counters

On Aug 24 09:33, Corinna Vinschen wrote:
> On Aug 22 13:23, Francois Romieu wrote:
> > Corinna Vinschen <vinschen@...hat.com> :
> > [...]
> > > That won't happen with the current patch because only
> > > rtl8169_reset_counters would print a log message, it's only called from
> > > open, and open occurs rather seldom.  Atop of that the code only tries
> > > to reset counters on HW supporting it, and only if resetting on the HW
> > > fails, there will be a log message at all.  There's no reasonable chance
> > > that failing to reset the counters will lead to log flooding.
> > 
> > Thanks for reformulating it. We are in violent agreement here.
> > 
> > [...]
> > > I'm not trying to avoid work, I'm trying to understand.
> > > 
> > > As far as I see it failing to reset the counters has no impact on the
> > > viability of the code.  It's still working with offsets and if the
> > > offset is 0 or non-0, the user space won't see the difference in the
> > > values returned by @get_stats64.  Successful resetting the counters is
> > > just a bonus.
> > 
> > Sorry, my english was really bad:
> > 
> > the code should propagate failure when rtl8169_reset_counters and
> > rtl8169_update_counters *simultaneously* fail.
> 
> Uhm... sorry, but that still doesn't answer the question.  As you can
> see in my patch, the initalization at open time is already encapsulated
> in a function rtl8169_init_counter_offsets. 
> 
> Assuming rtl8169_init_counter_offsets returns -1 if both functions,
> rtl8169_reset_counters and rtl8169_update_counters fail.
> 
> Then... what?
> 
> Not being able to reset or update the counters is still not at all fatal
> for the operation of the NIC as a whole and rtl_open in particular:
> 
>   rtl_open()
>   {
>     [...]
> 
>     /* This is non-fatal. */
>     if (!rtl8169_init_counter_offsets ()) {
> 
> 	  /* What to do here??? */
> 
>     }
> 
>     [...]
>   }

Never mind, I rearranged the code so that the warning is now printed
in rtl_open.  All functions related to the counter reset/update are
now bool functions.  I just sent a v3 patch.


Corinna

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