diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/cpumask.h | 75 |
1 files changed, 29 insertions, 46 deletions
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index b5ad19a6f43f..db2341beca45 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -416,65 +416,54 @@ int __next_cpu_nr(int n, const cpumask_t *srcp); /* * The following particular system cpumasks and operations manage - * possible, present, active and online cpus. Each of them is a fixed size - * bitmap of size NR_CPUS. + * possible, present, active and online cpus. * - * #ifdef CONFIG_HOTPLUG_CPU - * cpu_possible_map - has bit 'cpu' set iff cpu is populatable - * cpu_present_map - has bit 'cpu' set iff cpu is populated - * cpu_online_map - has bit 'cpu' set iff cpu available to scheduler - * cpu_active_map - has bit 'cpu' set iff cpu available to migration - * #else - * cpu_possible_map - has bit 'cpu' set iff cpu is populated - * cpu_present_map - copy of cpu_possible_map - * cpu_online_map - has bit 'cpu' set iff cpu available to scheduler - * #endif + * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable + * cpu_present_mask - has bit 'cpu' set iff cpu is populated + * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler + * cpu_active_mask - has bit 'cpu' set iff cpu available to migration * - * In either case, NR_CPUS is fixed at compile time, as the static - * size of these bitmaps. The cpu_possible_map is fixed at boot - * time, as the set of CPU id's that it is possible might ever - * be plugged in at anytime during the life of that system boot. - * The cpu_present_map is dynamic(*), representing which CPUs - * are currently plugged in. And cpu_online_map is the dynamic - * subset of cpu_present_map, indicating those CPUs available - * for scheduling. + * If !CONFIG_HOTPLUG_CPU, present == possible, and active == online. * - * If HOTPLUG is enabled, then cpu_possible_map is forced to have + * The cpu_possible_mask is fixed at boot time, as the set of CPU id's + * that it is possible might ever be plugged in at anytime during the + * life of that system boot. The cpu_present_mask is dynamic(*), + * representing which CPUs are currently plugged in. And + * cpu_online_mask is the dynamic subset of cpu_present_mask, + * indicating those CPUs available for scheduling. + * + * If HOTPLUG is enabled, then cpu_possible_mask is forced to have * all NR_CPUS bits set, otherwise it is just the set of CPUs that * ACPI reports present at boot. * - * If HOTPLUG is enabled, then cpu_present_map varies dynamically, + * If HOTPLUG is enabled, then cpu_present_mask varies dynamically, * depending on what ACPI reports as currently plugged in, otherwise - * cpu_present_map is just a copy of cpu_possible_map. + * cpu_present_mask is just a copy of cpu_possible_mask. * - * (*) Well, cpu_present_map is dynamic in the hotplug case. If not - * hotplug, it's a copy of cpu_possible_map, hence fixed at boot. + * (*) Well, cpu_present_mask is dynamic in the hotplug case. If not + * hotplug, it's a copy of cpu_possible_mask, hence fixed at boot. * * Subtleties: * 1) UP arch's (NR_CPUS == 1, CONFIG_SMP not defined) hardcode * assumption that their single CPU is online. The UP - * cpu_{online,possible,present}_maps are placebos. Changing them + * cpu_{online,possible,present}_masks are placebos. Changing them * will have no useful affect on the following num_*_cpus() * and cpu_*() macros in the UP case. This ugliness is a UP * optimization - don't waste any instructions or memory references * asking if you're online or how many CPUs there are if there is * only one CPU. - * 2) Most SMP arch's #define some of these maps to be some - * other map specific to that arch. Therefore, the following - * must be #define macros, not inlines. To see why, examine - * the assembly code produced by the following. Note that - * set1() writes phys_x_map, but set2() writes x_map: - * int x_map, phys_x_map; - * #define set1(a) x_map = a - * inline void set2(int a) { x_map = a; } - * #define x_map phys_x_map - * main(){ set1(3); set2(5); } */ -extern cpumask_t cpu_possible_map; -extern cpumask_t cpu_online_map; -extern cpumask_t cpu_present_map; -extern cpumask_t cpu_active_map; +extern const struct cpumask *const cpu_possible_mask; +extern const struct cpumask *const cpu_online_mask; +extern const struct cpumask *const cpu_present_mask; +extern const struct cpumask *const cpu_active_mask; + +/* These strip const, as traditionally they weren't const. */ +#define cpu_possible_map (*(cpumask_t *)cpu_possible_mask) +#define cpu_online_map (*(cpumask_t *)cpu_online_mask) +#define cpu_present_map (*(cpumask_t *)cpu_present_mask) +#define cpu_active_map (*(cpumask_t *)cpu_active_mask) #if NR_CPUS > 1 #define num_online_cpus() cpus_weight_nr(cpu_online_map) @@ -1058,12 +1047,6 @@ static inline void free_bootmem_cpumask_var(cpumask_var_t mask) } #endif /* CONFIG_CPUMASK_OFFSTACK */ -/* The pointer versions of the maps, these will become the primary versions. */ -#define cpu_possible_mask ((const struct cpumask *)&cpu_possible_map) -#define cpu_online_mask ((const struct cpumask *)&cpu_online_map) -#define cpu_present_mask ((const struct cpumask *)&cpu_present_map) -#define cpu_active_mask ((const struct cpumask *)&cpu_active_map) - /* It's common to want to use cpu_all_mask in struct member initializers, * so it has to refer to an address rather than a pointer. */ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS); |