Re: [PATCH] core: fix the use of this_cpu_ptr

[Eric Dumazet <eric.dumazet@gmail.com>]

On Thu, 2013-03-28 at 17:42 +0800, roy.qing.li@gmail.com wrote:
> From: Li RongQing <roy.qing.li@gmail.com>
> 
> flush_tasklet is not percpu var, and percpu is percpu var, and
> 	this_cpu_ptr(&info->cache->percpu->flush_tasklet)
> is not equal to
> 	&this_cpu_ptr(info->cache->percpu)->flush_tasklet
> 
> 1f743b076(use this_cpu_ptr per-cpu helper) introduced this bug.
> 
> Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
> ---
>  net/core/flow.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/core/flow.c b/net/core/flow.c
> index 7fae135..e8084b8 100644
> --- a/net/core/flow.c
> +++ b/net/core/flow.c
> @@ -346,7 +346,7 @@ static void flow_cache_flush_per_cpu(void *data)
>  	struct flow_flush_info *info = data;
>  	struct tasklet_struct *tasklet;
>  
> -	tasklet = this_cpu_ptr(&info->cache->percpu->flush_tasklet);
> +	tasklet = &this_cpu_ptr(info->cache->percpu)->flush_tasklet;
>  	tasklet->data = (unsigned long)info;
>  	tasklet_schedule(tasklet);
>  }

Hi

Any reason you dont Cc Shan Wei & Christoph Lameter ?

Christoph, could this kind of error be detected by the compiler or
sparse ?

Thanks