Patchwork [v3,1/9] net: core: use this_cpu_ptr per-cpu helper

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Submitter Shan Wei
Date Nov. 9, 2012, 2:20 a.m.
Message ID <509C686F.20400@gmail.com>
Download mbox | patch
Permalink /patch/197913/
State Not Applicable
Delegated to: David Miller
Headers show

Comments

Shan Wei - Nov. 9, 2012, 2:20 a.m.
From: Shan Wei <davidshan@tencent.com>

flush_tasklet is a struct, not a pointer in percpu var.
so use this_cpu_ptr to get the member pointer.

Signed-off-by: Shan Wei <davidshan@tencent.com>
---
 net/core/flow.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)
Christoph Lameter - Nov. 9, 2012, 8:08 p.m.
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.


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Eric Dumazet - Nov. 9, 2012, 8:15 p.m.
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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Christoph Lameter - Nov. 12, 2012, 11:29 p.m.
On Fri, 9 Nov 2012, Eric Dumazet wrote:

> Its not the case.
>
> We need the _pointer_ to call :
>
> tasklet_schedule(tasklet);

Ah. Ok. In that case

Reviewed-by: Christoph Lameter <cl@linux.com>

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Patch

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;
 	tasklet_schedule(tasklet);
 }