["RFC PATCH" 2/2] powerpc/mm: Conslidate numa_enable check and min_common_depth check

[Vaibhav Jain]

"Aneesh Kumar K.V" <aneesh.kumar at linux.ibm.com> writes:

> Update min_common_depth = -1 if numa is disabled. This
> help us to avoid checking for both in different code paths.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> ---
>  arch/powerpc/mm/numa.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index f6d68baeaa96..c84062a390cc 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -212,7 +212,7 @@ static int associativity_to_nid(const __be32 *associativity)
>  {
>  	int nid = NUMA_NO_NODE;
>  
> -	if (min_common_depth == -1 || !numa_enabled)
> +	if (min_common_depth == -1)
>  		goto out;
>  
>  	if (of_read_number(associativity, 1) >= min_common_depth)
> @@ -625,6 +625,7 @@ static int __init parse_numa_properties(void)
>  
>  	if (numa_enabled == 0) {
>  		printk(KERN_WARNING "NUMA disabled by user\n");
> +		min_common_depth = -1;
>  		return -1;
>  	}

I would prefer updating the definition of variable 'min_common_depth' to

static int min_common_depth = -1;

This would handle the case where someone calls 'associativity_to_nid()' and
other functions that read 'min_common_depth' and get an invalid result
back. And also handle the case where kernel is booted with 'numa = off'.

Also the init value 'min_common_depth == 0' indicates that the
first word in "ibm,associativity" array represents the node-id which is
wrong. Instead its the length of the "ibm,associativity" array.

>  
> @@ -747,7 +748,7 @@ void __init dump_numa_cpu_topology(void)
>  	unsigned int node;
>  	unsigned int cpu, count;
>  
> -	if (min_common_depth == -1 || !numa_enabled)
> +	if (min_common_depth == -1)
>  		return;
>  
>  	for_each_online_node(node) {
> @@ -812,7 +813,7 @@ static void __init find_possible_nodes(void)
>  	struct device_node *rtas;
>  	u32 numnodes, i;
>  
> -	if (min_common_depth <= 0 || !numa_enabled)
> +	if (min_common_depth <= 0)
>  		return;
>  
>  	rtas = of_find_node_by_path("/rtas");
> @@ -1014,7 +1015,7 @@ int hot_add_scn_to_nid(unsigned long scn_addr)
>  	struct device_node *memory = NULL;
>  	int nid;
>  
> -	if (!numa_enabled || (min_common_depth < 0))
> +	if (min_common_depth < 0)
>  		return first_online_node;
>  
>  	memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
> -- 
> 2.21.0
>

-- 
Vaibhav Jain <vaibhav at linux.ibm.com>
Linux Technology Center, IBM India Pvt. Ltd.