x86-64, NUMA: Clean up initmem_init()

This patch cleans initmem_init() so that it is more readable and doesn't
use an unnecessary array of function pointers to convolute the flow of
the code.  It also makes it obvious that dummy_numa_init() will always
succeed (and documents that requirement) so that the existing BUG() is
never actually reached.

No functional change.

-tj: Updated comment for dummy_numa_init() slightly.

Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/arch/x86/mm/numa_64.c b/arch/x86/mm/numa_64.c
index 86491ba568d92e480903a06d6a4ec9061bfc9c1f..9ec0f209a6a4e3fd1a7390d206bfdad33e24c85b 100644 (file)
--- a/arch/x86/mm/numa_64.c
+++ b/arch/x86/mm/numa_64.c
@@ -562,6 +562,15 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
        return 0;
 }
 
+/**
+ * dummy_numma_init - Fallback dummy NUMA init
+ *
+ * Used if there's no underlying NUMA architecture, NUMA initialization
+ * fails, or NUMA is disabled on the command line.
+ *
+ * Must online at least one node and add memory blocks that cover all
+ * allowed memory.  This function must not fail.
+ */
 static int __init dummy_numa_init(void)
 {
        printk(KERN_INFO "%s\n",
@@ -575,57 +584,64 @@ static int __init dummy_numa_init(void)
        return 0;
 }
 
-void __init initmem_init(void)
+static int __init numa_init(int (*init_func)(void))
 {
-       int (*numa_init[])(void) = { [2] = dummy_numa_init };
-       int i, j;
-
-       if (!numa_off) {
-#ifdef CONFIG_ACPI_NUMA
-               numa_init[0] = x86_acpi_numa_init;
-#endif
-#ifdef CONFIG_AMD_NUMA
-               numa_init[1] = amd_numa_init;
-#endif
-       }
+       int i;
+       int ret;
 
-       for (i = 0; i < ARRAY_SIZE(numa_init); i++) {
-               if (!numa_init[i])
-                       continue;
+       for (i = 0; i < MAX_LOCAL_APIC; i++)
+               set_apicid_to_node(i, NUMA_NO_NODE);
 
-               for (j = 0; j < MAX_LOCAL_APIC; j++)
-                       set_apicid_to_node(j, NUMA_NO_NODE);
+       nodes_clear(numa_nodes_parsed);
+       nodes_clear(node_possible_map);
+       nodes_clear(node_online_map);
+       memset(&numa_meminfo, 0, sizeof(numa_meminfo));
+       remove_all_active_ranges();
+       numa_reset_distance();
 
-               nodes_clear(numa_nodes_parsed);
-               nodes_clear(node_possible_map);
-               nodes_clear(node_online_map);
-               memset(&numa_meminfo, 0, sizeof(numa_meminfo));
-               remove_all_active_ranges();
-               numa_reset_distance();
+       ret = init_func();
+       if (ret < 0)
+               return ret;
+       ret = numa_cleanup_meminfo(&numa_meminfo);
+       if (ret < 0)
+               return ret;
 
-               if (numa_init[i]() < 0)
-                       continue;
+       numa_emulation(&numa_meminfo, numa_distance_cnt);
 
-               if (numa_cleanup_meminfo(&numa_meminfo) < 0)
-                       continue;
+       ret = numa_register_memblks(&numa_meminfo);
+       if (ret < 0)
+               return ret;
 
-               numa_emulation(&numa_meminfo, numa_distance_cnt);
+       for (i = 0; i < nr_cpu_ids; i++) {
+               int nid = early_cpu_to_node(i);
 
-               if (numa_register_memblks(&numa_meminfo) < 0)
+               if (nid == NUMA_NO_NODE)
                        continue;
+               if (!node_online(nid))
+                       numa_clear_node(i);
+       }
+       numa_init_array();
+       return 0;
+}
 
-               for (j = 0; j < nr_cpu_ids; j++) {
-                       int nid = early_cpu_to_node(j);
+void __init initmem_init(void)
+{
+       int ret;
 
-                       if (nid == NUMA_NO_NODE)
-                               continue;
-                       if (!node_online(nid))
-                               numa_clear_node(j);
-               }
-               numa_init_array();
-               return;
+       if (!numa_off) {
+#ifdef CONFIG_ACPI_NUMA
+               ret = numa_init(x86_acpi_numa_init);
+               if (!ret)
+                       return;
+#endif
+#ifdef CONFIG_AMD_NUMA
+               ret = numa_init(amd_numa_init);
+               if (!ret)
+                       return;
+#endif
        }
-       BUG();
+
+       numa_init(dummy_numa_init);
 }
 
 unsigned long __init numa_free_all_bootmem(void)