diff options
Diffstat (limited to 'include/linux/smp.h')
| -rw-r--r-- | include/linux/smp.h | 40 |
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(); }) |