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Date: Mon, 1 Dec 2008 18:47:38 +1030
From: Rusty Russell <rusty@...tcorp.com.au>
To: linux-kernel@...r.kernel.org
Cc: Mike Travis <travis@....com>, Ingo Molnar <mingo@...e.hu>
Subject: [PATCH 4/6] cpumask: switch over to cpu_online/possible/active/present_mask: core
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@...tcorp.com.au>
Signed-off-by: Mike Travis <travis@....com>
---
include/linux/cpumask.h | 75 ++++++++++++++++++------------------------------
kernel/cpu.c | 49 ++++++++++++++-----------------
2 files changed, 52 insertions(+), 72 deletions(-)
diff -r a8a764f1893f include/linux/cpumask.h
--- a/include/linux/cpumask.h Tue Nov 18 21:11:37 2008 +1030
+++ b/include/linux/cpumask.h Tue Nov 18 21:15:28 2008 +1030
@@ -416,65 +416,54 @@
/*
* 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)
@@ -1044,12 +1033,6 @@
}
#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);
diff -r a8a764f1893f kernel/cpu.c
--- a/kernel/cpu.c Tue Nov 18 21:11:37 2008 +1030
+++ b/kernel/cpu.c Tue Nov 18 21:15:28 2008 +1030
@@ -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);
@@ -64,8 +42,6 @@
mutex_init(&cpu_hotplug.lock);
cpu_hotplug.refcount = 0;
}
-
-cpumask_t cpu_active_map;
#ifdef CONFIG_HOTPLUG_CPU
@@ -97,7 +73,7 @@
/*
* 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)
{
@@ -503,3 +479,24 @@
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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