[PATCH 1/9] sparc32: inspect every PROM CPU cache geometry

[Magnus Lindholm <linmag7@gmail.com>]

Cache discovery runs from setup_arch(), before secondary CPUs are online.
Using cpu_online() to terminate the PROM walk therefore stops after the
first CPU node on SMP systems. It cannot determine the largest cache and
smallest line size across all modules when their geometry differs. Sparse
logical CPU numbering is not required to trigger this.

Walk every PROM CPU node on SMP and retain the single-node UP behavior.
Start at the first child instead of skipping directly to its sibling, and
track whether a CPU was found independently of the end sentinel. No mixed-
module hardware failure is claimed by this change.

Signed-off-by: Magnus Lindholm <linmag7@gmail.com>
---
 arch/sparc/mm/srmmu.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/sparc/mm/srmmu.c b/arch/sparc/mm/srmmu.c
index b491d7b32891..49d41b33aabf 100644
--- a/arch/sparc/mm/srmmu.c
+++ b/arch/sparc/mm/srmmu.c
@@ -964,17 +964,18 @@ static void __init init_vac_layout(void)
 {
 	phandle nd;
 	int cache_lines;
+	bool found_cpu = false;
 	char node_str[128];
 #ifdef CONFIG_SMP
-	int cpu = 0;
 	unsigned long max_size = 0;
 	unsigned long min_line_size = 0x10000000;
 #endif
 
-	nd = prom_getchild(prom_root_node);
-	while ((nd = prom_getsibling(nd)) != 0) {
+	for (nd = prom_getchild(prom_root_node); nd != 0;
+	     nd = prom_getsibling(nd)) {
 		prom_getstring(nd, "device_type", node_str, sizeof(node_str));
 		if (!strcmp(node_str, "cpu")) {
+			found_cpu = true;
 			vac_line_size = prom_getint(nd, "cache-line-size");
 			if (vac_line_size == -1) {
 				prom_printf("can't determine cache-line-size, halting.\n");
@@ -992,16 +993,12 @@ static void __init init_vac_layout(void)
 				max_size = vac_cache_size;
 			if (vac_line_size < min_line_size)
 				min_line_size = vac_line_size;
-			//FIXME: cpus not contiguous!!
-			cpu++;
-			if (cpu >= nr_cpu_ids || !cpu_online(cpu))
-				break;
 #else
 			break;
 #endif
 		}
 	}
-	if (nd == 0) {
+	if (!found_cpu) {
 		prom_printf("No CPU nodes found, halting.\n");
 		prom_halt();
 	}
-- 
2.43.0