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cpumask: switch over to cpu_online/possible/active/present_mask: core
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Impact: cleanup

This implements the obsolescent cpu_online_map in terms of
cpu_online_mask, rather than the other way around.  Same for the other
maps.

The documentation comments are also updated to refer to _mask rather
than _map.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
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Rusty Russell committed Dec 29, 2008
1 parent cb78a0c commit b3199c0
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Showing 2 changed files with 52 additions and 72 deletions.
75 changes: 29 additions & 46 deletions include/linux/cpumask.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down Expand Up @@ -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);
Expand Down
49 changes: 23 additions & 26 deletions kernel/cpu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,30 +15,8 @@
#include <linux/stop_machine.h>
#include <linux/mutex.h>

/*
* Represents all cpu's present in the system
* In systems capable of hotplug, this map could dynamically grow
* as new cpu's are detected in the system via any platform specific
* method, such as ACPI for e.g.
*/
cpumask_t cpu_present_map __read_mostly;
EXPORT_SYMBOL(cpu_present_map);

/*
* Represents all cpu's that are currently online.
*/
cpumask_t cpu_online_map __read_mostly;
EXPORT_SYMBOL(cpu_online_map);

#ifdef CONFIG_INIT_ALL_POSSIBLE
cpumask_t cpu_possible_map __read_mostly = CPU_MASK_ALL;
#else
cpumask_t cpu_possible_map __read_mostly;
#endif
EXPORT_SYMBOL(cpu_possible_map);

#ifdef CONFIG_SMP
/* Serializes the updates to cpu_online_map, cpu_present_map */
/* Serializes the updates to cpu_online_mask, cpu_present_mask */
static DEFINE_MUTEX(cpu_add_remove_lock);

static __cpuinitdata RAW_NOTIFIER_HEAD(cpu_chain);
Expand All @@ -65,8 +43,6 @@ void __init cpu_hotplug_init(void)
cpu_hotplug.refcount = 0;
}

cpumask_t cpu_active_map;

#ifdef CONFIG_HOTPLUG_CPU

void get_online_cpus(void)
Expand Down Expand Up @@ -97,7 +73,7 @@ EXPORT_SYMBOL_GPL(put_online_cpus);

/*
* The following two API's must be used when attempting
* to serialize the updates to cpu_online_map, cpu_present_map.
* to serialize the updates to cpu_online_mask, cpu_present_mask.
*/
void cpu_maps_update_begin(void)
{
Expand Down Expand Up @@ -503,3 +479,24 @@ EXPORT_SYMBOL_GPL(cpu_bit_bitmap);

const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
EXPORT_SYMBOL(cpu_all_bits);

#ifdef CONFIG_INIT_ALL_POSSIBLE
static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly
= CPU_BITS_ALL;
#else
static DECLARE_BITMAP(cpu_possible_bits, CONFIG_NR_CPUS) __read_mostly;
#endif
const struct cpumask *const cpu_possible_mask = to_cpumask(cpu_possible_bits);
EXPORT_SYMBOL(cpu_possible_mask);

static DECLARE_BITMAP(cpu_online_bits, CONFIG_NR_CPUS) __read_mostly;
const struct cpumask *const cpu_online_mask = to_cpumask(cpu_online_bits);
EXPORT_SYMBOL(cpu_online_mask);

static DECLARE_BITMAP(cpu_present_bits, CONFIG_NR_CPUS) __read_mostly;
const struct cpumask *const cpu_present_mask = to_cpumask(cpu_present_bits);
EXPORT_SYMBOL(cpu_present_mask);

static DECLARE_BITMAP(cpu_active_bits, CONFIG_NR_CPUS) __read_mostly;
const struct cpumask *const cpu_active_mask = to_cpumask(cpu_active_bits);
EXPORT_SYMBOL(cpu_active_mask);

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