Subject: Re: [PATCH] percpu: convert SNMP mibs to new infra

From: Tejun Heo <[email-masked]>
Date: Fri, 03 Apr 2009 09:39:22 +0900

Eric Dumazet wrote:
...
>  #define percpu_read(var)	percpu_from_op("mov", per_cpu__##var)
>  #define percpu_write(var, val)	percpu_to_op("mov", per_cpu__##var, val)
>  #define percpu_add(var, val)	percpu_to_op("add", per_cpu__##var, val)
> +#define percpu_ptr_add(var, val)	percpu_to_op("add", *(var), val)
> +#define percpu_ptr_inc(var)       percpu_ptr_add(var, 1)
> +#define percpu_ptr_dec(var)       percpu_ptr_add(var, -1)
>  #define percpu_sub(var, val)	percpu_to_op("sub", per_cpu__##var, val)
>  #define percpu_and(var, val)	percpu_to_op("and", per_cpu__##var, val)
>  #define percpu_or(var, val)	percpu_to_op("or", per_cpu__##var, val)

x86 part looks fine to me.

> diff --git a/include/net/snmp.h b/include/net/snmp.h
> index 57c9362..1ba584b 100644
> --- a/include/net/snmp.h
> +++ b/include/net/snmp.h
> @@ -123,15 +123,31 @@ struct linux_xfrm_mib {
>  };
>  
>  /* 
> - * FIXME: On x86 and some other CPUs the split into user and softirq parts
> + * On x86 and some other CPUs the split into user and softirq parts
>   * is not needed because addl $1,memory is atomic against interrupts (but 
> - * atomic_inc would be overkill because of the lock cycles). Wants new 
> - * nonlocked_atomic_inc() primitives -AK
> + * atomic_inc would be overkill because of the lock cycles).
>   */ 
> +#ifdef CONFIG_X86
> +# define SNMP_ARRAY_SZ 1
> +#else
> +# define SNMP_ARRAY_SZ 2
> +#endif

This is quite hacky but, well, for the time being...

Thanks.

-- 
tejun