netdev - Re: [PATCH v3 1/9] net: core: use this_cpu

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Date:	Fri, 09 Nov 2012 12:15:44 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Shan Wei <shanwei88@...il.com>, David Miller <davem@...emloft.net>,
	timo.teras@....fi, steffen.klassert@...unet.com,
	NetDev <netdev@...r.kernel.org>,
	Kernel-Maillist <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/9] net: core: use this_cpu_ptr per-cpu helper

On Fri, 2012-11-09 at 20:08 +0000, Christoph Lameter wrote:
> On Fri, 9 Nov 2012, Shan Wei wrote:
> 
> > diff --git a/net/core/flow.c b/net/core/flow.c
> > index e318c7e..b0901ee 100644
> > --- a/net/core/flow.c
> > +++ b/net/core/flow.c
> > @@ -327,11 +327,9 @@ static void flow_cache_flush_tasklet(unsigned long data)
> >  static void flow_cache_flush_per_cpu(void *data)
> >  {
> >  	struct flow_flush_info *info = data;
> > -	int cpu;
> >  	struct tasklet_struct *tasklet;
> >
> > -	cpu = smp_processor_id();
> > -	tasklet = &per_cpu_ptr(info->cache->percpu, cpu)->flush_tasklet;
> > +	tasklet = this_cpu_ptr(&info->cache->percpu->flush_tasklet);
> >  	tasklet->data = (unsigned long)info;
> 
> this_cpu_write(info->cache->percpu->flush_tasklet->data, (unsigned
> 	long)info);
> 
> should also do the trick in less instructions and get rid of all temporary
> variables as well.

Its not the case.

We need the _pointer_ to call :

tasklet_schedule(tasklet);




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