Re: cpumask: fix compat getaffinity

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

> How's this?
> 
> cpumask: use nr_cpu_ids for printing and parsing cpumasks
> 
> Commit a45185d2d "cpumask: convert kernel/compat.c" broke
> libnuma, which abuses sched_getaffinity to find out NR_CPUS
> in order to parse /sys/devices/system/node/node*/cpumap.
> 
> However, the result now returned reflects nr_cpu_ids, and
> cpumask_scnprintf et al. use nr_cpumask_bits which is NR_CPUS (for
> CONFIG_CPUMASK_OFFSTACK=n) or nr_cpu_ids (for
> CONFIG_CPUMASK_OFFSTACK=y).
> 
> We should use nr_cpu_ids consistently.
>
> Reported-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
> Cc: stable@kernel.org

Well, This patch seems to have ABI change. please don't send abi-change to -stable.

note: I'm not against this patch itself.


> 
> diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
> --- a/include/linux/cpumask.h
> +++ b/include/linux/cpumask.h
> @@ -529,7 +529,7 @@ static inline void cpumask_copy(struct c
>  static inline int cpumask_scnprintf(char *buf, int len,
>  				    const struct cpumask *srcp)
>  {
> -	return bitmap_scnprintf(buf, len, cpumask_bits(srcp), nr_cpumask_bits);
> +	return bitmap_scnprintf(buf, len, cpumask_bits(srcp), nr_cpu_ids);
>  }
>  
>  /**
> @@ -543,7 +543,7 @@ static inline int cpumask_scnprintf(char
>  static inline int cpumask_parse_user(const char __user *buf, int len,
>  				     struct cpumask *dstp)
>  {
> -	return bitmap_parse_user(buf, len, cpumask_bits(dstp), nr_cpumask_bits);
> +	return bitmap_parse_user(buf, len, cpumask_bits(dstp), nr_cpu_ids);
>  }
>  
>  /**
> @@ -558,8 +558,7 @@ static inline int cpumask_parse_user(con
>  static inline int cpulist_scnprintf(char *buf, int len,
>  				    const struct cpumask *srcp)
>  {
> -	return bitmap_scnlistprintf(buf, len, cpumask_bits(srcp),
> -				    nr_cpumask_bits);
> +	return bitmap_scnlistprintf(buf, len, cpumask_bits(srcp), nr_cpu_ids);
>  }
>  
>  /**
> @@ -572,7 +571,7 @@ static inline int cpulist_scnprintf(char
>   */
>  static inline int cpulist_parse(const char *buf, struct cpumask *dstp)
>  {
> -	return bitmap_parselist(buf, cpumask_bits(dstp), nr_cpumask_bits);
> +	return bitmap_parselist(buf, cpumask_bits(dstp), nr_cpu_ids);
>  }
>  
>  /**
> --
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