Subject: Re: [PATCH v6 6/6] powerpc/pseries: Consolidate form1 distance initialization into a helper

From: David Gibson <[email-masked]>
Date: Mon, 9 Aug 2021 13:27:08 +1000

On Fri, Aug 06, 2021 at 09:53:59PM +0530, Aneesh Kumar K.V wrote:
> On 8/6/21 12:17 PM, David Gibson wrote:
> > On Tue, Jul 27, 2021 at 03:33:11PM +0530, Aneesh Kumar K.V wrote:
> > > Currently, we duplicate parsing code for ibm,associativity and
> > > ibm,associativity-lookup-arrays in the kernel. The associativity array provided
> > > by these device tree properties are very similar and hence can use
> > > a helper to parse the node id and numa distance details.
> > 
> > Oh... sorry.. comments on the earlier patch were from before I read
> > and saw you adjusted things here.
> > 
> > > 
> > > Signed-off-by: Aneesh Kumar K.V <[email-masked]>
> > > ---
> > >   arch/powerpc/mm/numa.c | 83 ++++++++++++++++++++++++++----------------
> > >   1 file changed, 51 insertions(+), 32 deletions(-)
> > > 
> > > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> > > index fffb3c40f595..7506251e17f2 100644
> > > --- a/arch/powerpc/mm/numa.c
> > > +++ b/arch/powerpc/mm/numa.c
> > > @@ -171,19 +171,19 @@ static void unmap_cpu_from_node(unsigned long cpu)
> > >   }
> > >   #endif /* CONFIG_HOTPLUG_CPU || CONFIG_PPC_SPLPAR */
> > > -/*
> > > - * Returns nid in the range [0..nr_node_ids], or -1 if no useful NUMA
> > > - * info is found.
> > > - */
> > > -static int associativity_to_nid(const __be32 *associativity)
> > > +static int __associativity_to_nid(const __be32 *associativity,
> > > +				  int max_array_sz)
> > >   {
> > >   	int nid = NUMA_NO_NODE;
> > > +	/*
> > > +	 * primary_domain_index is 1 based array index.
> > > +	 */
> > > +	int index = primary_domain_index  - 1;
> > > -	if (!numa_enabled)
> > > +	if (!numa_enabled || index >= max_array_sz)
> > >   		goto out;
> > 
> > You don't need a goto, you can just return NUMA_NO_NODE.
> 
> updated
> 
> > 
> > > -	if (of_read_number(associativity, 1) >= primary_domain_index)
> > > -		nid = of_read_number(&associativity[primary_domain_index], 1);
> > > +	nid = of_read_number(&associativity[index], 1);
> > >   	/* POWER4 LPAR uses 0xffff as invalid node */
> > >   	if (nid == 0xffff || nid >= nr_node_ids)
> > > @@ -191,6 +191,17 @@ static int associativity_to_nid(const __be32 *associativity)
> > >   out:
> > >   	return nid;
> > >   }
> > > +/*
> > > + * Returns nid in the range [0..nr_node_ids], or -1 if no useful NUMA
> > > + * info is found.
> > > + */
> > > +static int associativity_to_nid(const __be32 *associativity)
> > > +{
> > > +	int array_sz = of_read_number(associativity, 1);
> > > +
> > > +	/* Skip the first element in the associativity array */
> > > +	return __associativity_to_nid((associativity + 1), array_sz);
> > > +}
> > >   static int __cpu_form2_relative_distance(__be32 *cpu1_assoc, __be32 *cpu2_assoc)
> > >   {
> > > @@ -295,24 +306,41 @@ int of_node_to_nid(struct device_node *device)
> > >   }
> > >   EXPORT_SYMBOL(of_node_to_nid);
> > > -static void __initialize_form1_numa_distance(const __be32 *associativity)
> > > +static void ___initialize_form1_numa_distance(const __be32 *associativity,
> > > +					     int max_array_sz)
> > >   {
> > >   	int i, nid;
> > >   	if (affinity_form != FORM1_AFFINITY)
> > >   		return;
> > > -	nid = associativity_to_nid(associativity);
> > > +	nid = __associativity_to_nid(associativity, max_array_sz);
> > >   	if (nid != NUMA_NO_NODE) {
> > >   		for (i = 0; i < distance_ref_points_depth; i++) {
> > >   			const __be32 *entry;
> > > +			int index = be32_to_cpu(distance_ref_points[i]) - 1;
> > > +
> > > +			/*
> > > +			 * broken hierarchy, return with broken distance table
> > 
> > WARN_ON, maybe?
> 
> 
> updated
> 
> > 
> > > +			 */
> > > +			if (index >= max_array_sz)
> > > +				return;
> > > -			entry = &associativity[be32_to_cpu(distance_ref_points[i])];
> > > +			entry = &associativity[index];
> > >   			distance_lookup_table[nid][i] = of_read_number(entry, 1);
> > >   		}
> > >   	}
> > >   }
> > > +static void __initialize_form1_numa_distance(const __be32 *associativity)
> > 
> > Do you actually use this in-between wrapper?
> 
> yes used in
> 
> static void initialize_form1_numa_distance(struct device_node *node)
> {
> 	const __be32 *associativity;
> 
> 	associativity = of_get_associativity(node);
> 	if (!associativity)
> 		return;
> 
> 	__initialize_form1_numa_distance(associativity);

Right, but I mean in more than one place.  If this is the only user,
you might as well expand it inline here.

> }
> 
> 
> 
> > 
> > > +{
> > > +	int array_sz;
> > > +
> > > +	array_sz = of_read_number(associativity, 1);
> > > +	/* Skip the first element in the associativity array */
> > > +	___initialize_form1_numa_distance(associativity + 1, array_sz);
> > > +}
> > > +
> > >   static void initialize_form1_numa_distance(struct device_node *node)
> > >   {
> > >   	const __be32 *associativity;
> > > @@ -586,27 +614,18 @@ static int get_nid_and_numa_distance(struct drmem_lmb *lmb)
> > >   	if (primary_domain_index <= aa.array_sz &&
> > >   	    !(lmb->flags & DRCONF_MEM_AI_INVALID) && lmb->aa_index < aa.n_arrays) {
> > > -		index = lmb->aa_index * aa.array_sz + primary_domain_index - 1;
> > > -		nid = of_read_number(&aa.arrays[index], 1);
> > > +		const __be32 *associativity;
> > > -		if (nid == 0xffff || nid >= nr_node_ids)
> > > -			nid = default_nid;
> > > +		index = lmb->aa_index * aa.array_sz;
> > > +		associativity = &aa.arrays[index];
> > > +		nid = __associativity_to_nid(associativity, aa.array_sz);
> > >   		if (nid > 0 && affinity_form == FORM1_AFFINITY) {
> > > -			int i;
> > > -			const __be32 *associativity;
> > > -
> > > -			index = lmb->aa_index * aa.array_sz;
> > > -			associativity = &aa.arrays[index];
> > >   			/*
> > > -			 * lookup array associativity entries have different format
> > > -			 * There is no length of the array as the first element.
> > > +			 * lookup array associativity entries have
> > > +			 * no length of the array as the first element.
> > >   			 */
> > > -			for (i = 0; i < distance_ref_points_depth; i++) {
> > > -				const __be32 *entry;
> > > -
> > > -				entry = &associativity[be32_to_cpu(distance_ref_points[i]) - 1];
> > > -				distance_lookup_table[nid][i] = of_read_number(entry, 1);
> > > -			}
> > > +			___initialize_form1_numa_distance(associativity,
> > > +							  aa.array_sz);
> > 
> > Better, thanks.
> > 
> > >   		}
> > >   	}
> > >   	return nid;
> > > @@ -632,11 +651,11 @@ int of_drconf_to_nid_single(struct drmem_lmb *lmb)
> > >   	if (primary_domain_index <= aa.array_sz &&
> > >   	    !(lmb->flags & DRCONF_MEM_AI_INVALID) && lmb->aa_index < aa.n_arrays) {
> > > -		index = lmb->aa_index * aa.array_sz + primary_domain_index - 1;
> > > -		nid = of_read_number(&aa.arrays[index], 1);
> > > +		const __be32 *associativity;
> > > -		if (nid == 0xffff || nid >= nr_node_ids)
> > > -			nid = default_nid;
> > > +		index = lmb->aa_index * aa.array_sz;
> > > +		associativity = &aa.arrays[index];
> > > +		nid = __associativity_to_nid(associativity, aa.array_sz);
> > >   	}
> > >   	return nid;
> > >   }
> > 
> 
> 
> -aneesh
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson