7ff6f08295
This patch splits alloc_percpu() up into two phases. Likewise for free_percpu(). This allows clients to limit initial allocations to online cpu's, and to populate or depopulate per-cpu data at run time as needed: struct my_struct *obj; /* initial allocation for online cpu's */ obj = percpu_alloc(sizeof(struct my_struct), GFP_KERNEL); ... /* populate per-cpu data for cpu coming online */ ptr = percpu_populate(obj, sizeof(struct my_struct), GFP_KERNEL, cpu); ... /* access per-cpu object */ ptr = percpu_ptr(obj, smp_processor_id()); ... /* depopulate per-cpu data for cpu going offline */ percpu_depopulate(obj, cpu); ... /* final removal */ percpu_free(obj); Signed-off-by: Martin Peschke <mp3@de.ibm.com> Cc: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
107 lines
3.0 KiB
C
107 lines
3.0 KiB
C
#ifndef __LINUX_PERCPU_H
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#define __LINUX_PERCPU_H
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#include <linux/spinlock.h> /* For preempt_disable() */
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#include <linux/slab.h> /* For kmalloc() */
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#include <linux/smp.h>
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#include <linux/string.h> /* For memset() */
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#include <linux/cpumask.h>
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#include <asm/percpu.h>
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/* Enough to cover all DEFINE_PER_CPUs in kernel, including modules. */
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#ifndef PERCPU_ENOUGH_ROOM
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#define PERCPU_ENOUGH_ROOM 32768
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#endif
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/*
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* Must be an lvalue. Since @var must be a simple identifier,
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* we force a syntax error here if it isn't.
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*/
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#define get_cpu_var(var) (*({ \
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extern int simple_indentifier_##var(void); \
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preempt_disable(); \
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&__get_cpu_var(var); }))
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#define put_cpu_var(var) preempt_enable()
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#ifdef CONFIG_SMP
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struct percpu_data {
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void *ptrs[NR_CPUS];
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};
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#define __percpu_disguise(pdata) (struct percpu_data *)~(unsigned long)(pdata)
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/*
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* Use this to get to a cpu's version of the per-cpu object dynamically
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* allocated. Non-atomic access to the current CPU's version should
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* probably be combined with get_cpu()/put_cpu().
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*/
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#define percpu_ptr(ptr, cpu) \
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({ \
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struct percpu_data *__p = __percpu_disguise(ptr); \
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(__typeof__(ptr))__p->ptrs[(cpu)]; \
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})
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extern void *percpu_populate(void *__pdata, size_t size, gfp_t gfp, int cpu);
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extern void percpu_depopulate(void *__pdata, int cpu);
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extern int __percpu_populate_mask(void *__pdata, size_t size, gfp_t gfp,
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cpumask_t *mask);
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extern void __percpu_depopulate_mask(void *__pdata, cpumask_t *mask);
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extern void *__percpu_alloc_mask(size_t size, gfp_t gfp, cpumask_t *mask);
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extern void percpu_free(void *__pdata);
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#else /* CONFIG_SMP */
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#define percpu_ptr(ptr, cpu) ({ (void)(cpu); (ptr); })
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static inline void percpu_depopulate(void *__pdata, int cpu)
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{
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}
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static inline void __percpu_depopulate_mask(void *__pdata, cpumask_t *mask)
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{
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}
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static inline void *percpu_populate(void *__pdata, size_t size, gfp_t gfp,
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int cpu)
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{
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return percpu_ptr(__pdata, cpu);
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}
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static inline int __percpu_populate_mask(void *__pdata, size_t size, gfp_t gfp,
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cpumask_t *mask)
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{
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return 0;
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}
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static inline void *__percpu_alloc_mask(size_t size, gfp_t gfp, cpumask_t *mask)
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{
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return kzalloc(size, gfp);
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}
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static inline void percpu_free(void *__pdata)
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{
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kfree(__pdata);
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}
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#endif /* CONFIG_SMP */
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#define percpu_populate_mask(__pdata, size, gfp, mask) \
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__percpu_populate_mask((__pdata), (size), (gfp), &(mask))
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#define percpu_depopulate_mask(__pdata, mask) \
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__percpu_depopulate_mask((__pdata), &(mask))
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#define percpu_alloc_mask(size, gfp, mask) \
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__percpu_alloc_mask((size), (gfp), &(mask))
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#define percpu_alloc(size, gfp) percpu_alloc_mask((size), (gfp), cpu_online_map)
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/* (legacy) interface for use without CPU hotplug handling */
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#define __alloc_percpu(size) percpu_alloc_mask((size), GFP_KERNEL, \
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cpu_possible_map)
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#define alloc_percpu(type) (type *)__alloc_percpu(sizeof(type))
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#define free_percpu(ptr) percpu_free((ptr))
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#define per_cpu_ptr(ptr, cpu) percpu_ptr((ptr), (cpu))
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#endif /* __LINUX_PERCPU_H */
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