netdev - Re: [PATCH 1/8] New driver "sfc" for Solarstorm SFC4000 controller (try #8)

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Message-ID: <20080325125421.GB24160@solarflare.com>
Date:	Tue, 25 Mar 2008 12:54:23 +0000
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, linux-net-drivers@...arflare.com,
	jgarzik@...ox.com
Subject: Re: [PATCH 1/8] New driver "sfc" for Solarstorm SFC4000 controller (try #8)

David Miller wrote:
> From: Ben Hutchings <bhutchings@...arflare.com>
> Date: Mon, 24 Mar 2008 10:29:38 +0000
> 
> > David Miller wrote:
> > > > +
> > > > +		if (rss_cpus == 0) {
> > > > +#ifdef topology_core_siblings
> > > > +			cpumask_t core_mask;
> > > > +			int cpu;
> > > > +
> > > > +			cpus_clear(core_mask);
> > > > +			efx->rss_queues = 0;
> > > > +			for_each_online_cpu(cpu) {
> > > > +				if (!cpu_isset(cpu, core_mask)) {
> > > > +					++efx->rss_queues;
> > > > +					cpus_or(core_mask, core_mask,
> > > > +						topology_core_siblings(cpu));
> > > > +				}
> > > > +			}
> > > > +#else
> > > > +			efx->rss_queues = num_online_cpus();
> > > > +#endif
> > > 
> > > Please don't test feature availability this way.
> > > 
> > > Either use the proper CONFIG_* option ifdef.
> > 
> > The macro is defined for some architectures and not for others, and does
> > not depend on config options.  See Documentation/cputopology.txt.
> 
> Then this needs to be fixed at the top level because drivers doing
> this is beyond ugly.
> 
> I'd suggest that some default define be provided by the generic
> header files so code doesn't have to do this.

That would certainly be better, yes.

Would you object to our using this test until the default definition exists?

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
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