x86: add debug of invalid per_cpu map accesses

Provide a means to trap usages of per_cpu map variables before
they are setup.  Define CONFIG_DEBUG_PER_CPU_MAPS to activate.

Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/asm-x86/topology.h b/include/asm-x86/topology.h
index 040374f030cf..f1e12329078e 100644
--- a/include/asm-x86/topology.h
+++ b/include/asm-x86/topology.h
@@ -66,6 +66,13 @@ static inline int early_cpu_to_node(int cpu)
 
 static inline int cpu_to_node(int cpu)
 {
+#ifdef  CONFIG_DEBUG_PER_CPU_MAPS
+        if(x86_cpu_to_node_map_early_ptr) {
+                printk("KERN_NOTICE cpu_to_node(%d): usage too early!\n",
+                        (int)cpu);
+                BUG();
+        }
+#endif
         if(per_cpu_offset(cpu))
                 return per_cpu(x86_cpu_to_node_map, cpu);
         else