linux-kernel - [RFC PATCH] powerpc/numa: initialize distance lookup table from drconf path

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Date:	Wed, 10 Jun 2015 10:20:16 +0530
From:	Nikunj A Dadhania <nikunj@...ux.vnet.ibm.com>
To:	linuxppc-dev@...ts.ozlabs.org, paulus@...ba.org
Cc:	linux-kernel@...r.kernel.org, bharata@...ux.vnet.ibm.com,
	nikunj@...ux.vnet.ibm.com, anton@...ba.org
Subject: [RFC PATCH] powerpc/numa: initialize distance lookup table from drconf path

Node distance will not get initialized in certain cases as
dynamic-reconfiguration path does not initialize the lookup table.

There is an assumption about the associativity list in
initialize_distance_lookup_table(). Associativity list has two forms:

a) [cpu,memory]@x/ibm,associativity has following
   format:

    <N> <N integers>

b) ibm,dynamic-reconfiguration-memory/ibm,associativity-lookup-arrays

   <M> <N> <M*N integers>
   M = the number of associativity lists
   N = the number of entries per associativity list

Fix initialize_distance_lookup_table() so that it does not assume
"case a". And update the caller to skip the length field before
sending the associativity list.

Call initialize_distance_lookup_table() from drconf path with
appropriate associativity list.

Reported-by: Bharata B Rao <bharata@...ux.vnet.ibm.com>
Signed-off-by: Nikunj A Dadhania <nikunj@...ux.vnet.ibm.com>
---
 arch/powerpc/mm/numa.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 5e80621..8b9502a 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -225,7 +225,7 @@ static void initialize_distance_lookup_table(int nid,
 	for (i = 0; i < distance_ref_points_depth; i++) {
 		const __be32 *entry;
 
-		entry = &associativity[be32_to_cpu(distance_ref_points[i])];
+		entry = &associativity[be32_to_cpu(distance_ref_points[i]) - 1];
 		distance_lookup_table[nid][i] = of_read_number(entry, 1);
 	}
 }
@@ -248,8 +248,12 @@ static int associativity_to_nid(const __be32 *associativity)
 		nid = -1;
 
 	if (nid > 0 &&
-	    of_read_number(associativity, 1) >= distance_ref_points_depth)
-		initialize_distance_lookup_table(nid, associativity);
+		of_read_number(associativity, 1) >= distance_ref_points_depth) {
+		/*
+		 * Skip the length field and send start of associativity array
+		 */
+		initialize_distance_lookup_table(nid, associativity + 1);
+	}
 
 out:
 	return nid;
@@ -507,6 +511,12 @@ static int of_drconf_to_nid_single(struct of_drconf_cell *drmem,
 
 		if (nid == 0xffff || nid >= MAX_NUMNODES)
 			nid = default_nid;
+
+		if (nid > 0) {
+			index = drmem->aa_index * aa->array_sz;
+			initialize_distance_lookup_table(nid,
+							&aa->arrays[index]);
+		}
 	}
 
 	return nid;
-- 
1.8.3.1

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