1 files changed, 16 insertions, 24 deletions

diff --git a/include/linux/smp.h b/include/linux/smp.h
index dcf1db3b35d3..9dfa3ee769ae 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -92,10 +92,7 @@ void smp_prepare_boot_cpu(void);
 /*
  *      These macros fold the SMP functionality into a single CPU system
  */
-
-#if !defined(__smp_processor_id) || !defined(CONFIG_PREEMPT)
-# define smp_processor_id()                     0
-#endif
+#define raw_smp_processor_id()                  0
 #define hard_smp_processor_id()                 0
 #define smp_call_function(func,info,retry,wait) ({ 0; })
 #define on_each_cpu(func,info,retry,wait)       ({ func(info); 0; })
@@ -106,30 +103,25 @@ static inline void smp_send_reschedule(int cpu) { }
 #endif /* !SMP */
 
 /*
- * DEBUG_PREEMPT support: check whether smp_processor_id() is being
- * used in a preemption-safe way.
+ * smp_processor_id(): get the current CPU ID.
  *
- * An architecture has to enable this debugging code explicitly.
- * It can do so by renaming the smp_processor_id() macro to
- * __smp_processor_id().  This should only be done after some minimal
- * testing, because usually there are a number of false positives
- * that an architecture will trigger.
+ * if DEBUG_PREEMPT is enabled the we check whether it is
+ * used in a preemption-safe way. (smp_processor_id() is safe
+ * if it's used in a preemption-off critical section, or in
+ * a thread that is bound to the current CPU.)
  *
- * To fix a false positive (i.e. smp_processor_id() use that the
- * debugging code reports but which use for some reason is legal),
- * change the smp_processor_id() reference to _smp_processor_id(),
- * which is the nondebug variant.  NOTE: don't use this to hack around
- * real bugs.
+ * NOTE: raw_smp_processor_id() is for internal use only
+ * (smp_processor_id() is the preferred variant), but in rare
+ * instances it might also be used to turn off false positives
+ * (i.e. smp_processor_id() use that the debugging code reports but
+ * which use for some reason is legal). Don't use this to hack around
+ * the warning message, as your code might not work under PREEMPT.
  */
-#ifdef __smp_processor_id
-# if defined(CONFIG_PREEMPT) && defined(CONFIG_DEBUG_PREEMPT)
-   extern unsigned int smp_processor_id(void);
-# else
-#  define smp_processor_id() __smp_processor_id()
-# endif
-# define _smp_processor_id() __smp_processor_id()
+#ifdef CONFIG_DEBUG_PREEMPT
+  extern unsigned int debug_smp_processor_id(void);
+# define smp_processor_id() debug_smp_processor_id()
 #else
-# define _smp_processor_id() smp_processor_id()
+# define smp_processor_id() raw_smp_processor_id()
 #endif
 
 #define get_cpu()               ({ preempt_disable(); smp_processor_id(); })