Re: [PATCH 4/5] mm: add numa node symlink for cpu devices in sysfs

[David Rientjes]

On Mon, 19 Oct 2009, Alex Chiang wrote:

> You can discover which CPUs belong to a NUMA node by examining
> /sys/devices/system/node/$node/
> 

You mean /sys/devices/system/node/node# ?

> However, it's not convenient to go in the other direction, when looking at
> /sys/devices/system/cpu/$cpu/
> 

.../cpu/cpu# ?

> Yes, you can muck about in sysfs, but adding these symlinks makes
> life a lot more convenient.
> 
> Signed-off-by: Alex Chiang <achiang@xxxxxx>
> ---
> 
>  drivers/base/node.c |    9 ++++++++-
>  1 files changed, 8 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index ffda067..47a4997 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -227,6 +227,7 @@ struct node node_devices[MAX_NUMNODES];
>   */
>  int register_cpu_under_node(unsigned int cpu, unsigned int nid)
>  {
> +	int ret;
>  	struct sys_device *obj;
>  
>  	if (!node_online(nid))
> @@ -236,9 +237,13 @@ int register_cpu_under_node(unsigned int cpu, unsigned int nid)
>  	if (!obj)
>  		return 0;
>  
> -	return sysfs_create_link(&node_devices[nid].sysdev.kobj,
> +	ret = sysfs_create_link(&node_devices[nid].sysdev.kobj,
>  				&obj->kobj,
>  				kobject_name(&obj->kobj));
> +
> +	return sysfs_create_link(&obj->kobj,
> +				 &node_devices[nid].sysdev.kobj,
> +				 kobject_name(&node_devices[nid].sysdev.kobj));
>  }
>  
>  int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)

That can't be right, you're ignoring the return value of the first 
sysfs_create_link().

The return values of register_cpu_under_node() and 
unregister_cpu_under_node() are always ignored, so it would probably be 
best to convert these to be void functions.  That doesn't mean you can 
simply ignore the result of the first sysfs_create_link(), though: the 
second should probably be suppressed if the first returns an error.
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