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200 lines
4.7 KiB
200 lines
4.7 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* Copyright (c) 2016 Facebook |
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*/ |
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#include "percpu_freelist.h" |
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int pcpu_freelist_init(struct pcpu_freelist *s) |
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{ |
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int cpu; |
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s->freelist = alloc_percpu(struct pcpu_freelist_head); |
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if (!s->freelist) |
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return -ENOMEM; |
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for_each_possible_cpu(cpu) { |
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struct pcpu_freelist_head *head = per_cpu_ptr(s->freelist, cpu); |
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raw_spin_lock_init(&head->lock); |
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head->first = NULL; |
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} |
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raw_spin_lock_init(&s->extralist.lock); |
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s->extralist.first = NULL; |
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return 0; |
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} |
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void pcpu_freelist_destroy(struct pcpu_freelist *s) |
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{ |
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free_percpu(s->freelist); |
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} |
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static inline void pcpu_freelist_push_node(struct pcpu_freelist_head *head, |
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struct pcpu_freelist_node *node) |
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{ |
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node->next = head->first; |
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WRITE_ONCE(head->first, node); |
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} |
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static inline void ___pcpu_freelist_push(struct pcpu_freelist_head *head, |
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struct pcpu_freelist_node *node) |
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{ |
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raw_spin_lock(&head->lock); |
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pcpu_freelist_push_node(head, node); |
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raw_spin_unlock(&head->lock); |
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} |
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static inline bool pcpu_freelist_try_push_extra(struct pcpu_freelist *s, |
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struct pcpu_freelist_node *node) |
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{ |
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if (!raw_spin_trylock(&s->extralist.lock)) |
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return false; |
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pcpu_freelist_push_node(&s->extralist, node); |
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raw_spin_unlock(&s->extralist.lock); |
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return true; |
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} |
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static inline void ___pcpu_freelist_push_nmi(struct pcpu_freelist *s, |
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struct pcpu_freelist_node *node) |
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{ |
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int cpu, orig_cpu; |
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orig_cpu = raw_smp_processor_id(); |
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while (1) { |
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for_each_cpu_wrap(cpu, cpu_possible_mask, orig_cpu) { |
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struct pcpu_freelist_head *head; |
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head = per_cpu_ptr(s->freelist, cpu); |
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if (raw_spin_trylock(&head->lock)) { |
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pcpu_freelist_push_node(head, node); |
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raw_spin_unlock(&head->lock); |
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return; |
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} |
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} |
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/* cannot lock any per cpu lock, try extralist */ |
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if (pcpu_freelist_try_push_extra(s, node)) |
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return; |
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} |
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} |
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void __pcpu_freelist_push(struct pcpu_freelist *s, |
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struct pcpu_freelist_node *node) |
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{ |
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if (in_nmi()) |
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___pcpu_freelist_push_nmi(s, node); |
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else |
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___pcpu_freelist_push(this_cpu_ptr(s->freelist), node); |
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} |
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void pcpu_freelist_push(struct pcpu_freelist *s, |
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struct pcpu_freelist_node *node) |
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{ |
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unsigned long flags; |
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local_irq_save(flags); |
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__pcpu_freelist_push(s, node); |
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local_irq_restore(flags); |
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} |
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void pcpu_freelist_populate(struct pcpu_freelist *s, void *buf, u32 elem_size, |
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u32 nr_elems) |
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{ |
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struct pcpu_freelist_head *head; |
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unsigned int cpu, cpu_idx, i, j, n, m; |
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n = nr_elems / num_possible_cpus(); |
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m = nr_elems % num_possible_cpus(); |
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cpu_idx = 0; |
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for_each_possible_cpu(cpu) { |
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head = per_cpu_ptr(s->freelist, cpu); |
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j = n + (cpu_idx < m ? 1 : 0); |
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for (i = 0; i < j; i++) { |
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/* No locking required as this is not visible yet. */ |
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pcpu_freelist_push_node(head, buf); |
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buf += elem_size; |
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} |
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cpu_idx++; |
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} |
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} |
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static struct pcpu_freelist_node *___pcpu_freelist_pop(struct pcpu_freelist *s) |
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{ |
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struct pcpu_freelist_head *head; |
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struct pcpu_freelist_node *node; |
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int cpu; |
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for_each_cpu_wrap(cpu, cpu_possible_mask, raw_smp_processor_id()) { |
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head = per_cpu_ptr(s->freelist, cpu); |
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if (!READ_ONCE(head->first)) |
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continue; |
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raw_spin_lock(&head->lock); |
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node = head->first; |
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if (node) { |
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WRITE_ONCE(head->first, node->next); |
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raw_spin_unlock(&head->lock); |
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return node; |
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} |
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raw_spin_unlock(&head->lock); |
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} |
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/* per cpu lists are all empty, try extralist */ |
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if (!READ_ONCE(s->extralist.first)) |
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return NULL; |
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raw_spin_lock(&s->extralist.lock); |
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node = s->extralist.first; |
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if (node) |
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WRITE_ONCE(s->extralist.first, node->next); |
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raw_spin_unlock(&s->extralist.lock); |
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return node; |
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} |
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static struct pcpu_freelist_node * |
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___pcpu_freelist_pop_nmi(struct pcpu_freelist *s) |
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{ |
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struct pcpu_freelist_head *head; |
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struct pcpu_freelist_node *node; |
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int cpu; |
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for_each_cpu_wrap(cpu, cpu_possible_mask, raw_smp_processor_id()) { |
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head = per_cpu_ptr(s->freelist, cpu); |
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if (!READ_ONCE(head->first)) |
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continue; |
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if (raw_spin_trylock(&head->lock)) { |
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node = head->first; |
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if (node) { |
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WRITE_ONCE(head->first, node->next); |
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raw_spin_unlock(&head->lock); |
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return node; |
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} |
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raw_spin_unlock(&head->lock); |
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} |
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} |
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/* cannot pop from per cpu lists, try extralist */ |
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if (!READ_ONCE(s->extralist.first) || !raw_spin_trylock(&s->extralist.lock)) |
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return NULL; |
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node = s->extralist.first; |
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if (node) |
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WRITE_ONCE(s->extralist.first, node->next); |
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raw_spin_unlock(&s->extralist.lock); |
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return node; |
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} |
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struct pcpu_freelist_node *__pcpu_freelist_pop(struct pcpu_freelist *s) |
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{ |
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if (in_nmi()) |
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return ___pcpu_freelist_pop_nmi(s); |
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return ___pcpu_freelist_pop(s); |
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} |
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struct pcpu_freelist_node *pcpu_freelist_pop(struct pcpu_freelist *s) |
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{ |
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struct pcpu_freelist_node *ret; |
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unsigned long flags; |
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local_irq_save(flags); |
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ret = __pcpu_freelist_pop(s); |
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local_irq_restore(flags); |
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return ret; |
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}
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