![Ingo Molnar](/assets/img/avatar_default.png)
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273 lines
5.7 KiB
C
273 lines
5.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* kernel/sched/cpudl.c
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*
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* Global CPU deadline management
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*
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* Author: Juri Lelli <j.lelli@sssup.it>
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*/
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#include "sched.h"
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static inline int parent(int i)
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{
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return (i - 1) >> 1;
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}
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static inline int left_child(int i)
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{
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return (i << 1) + 1;
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}
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static inline int right_child(int i)
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{
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return (i << 1) + 2;
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}
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static void cpudl_heapify_down(struct cpudl *cp, int idx)
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{
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int l, r, largest;
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int orig_cpu = cp->elements[idx].cpu;
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u64 orig_dl = cp->elements[idx].dl;
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if (left_child(idx) >= cp->size)
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return;
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/* adapted from lib/prio_heap.c */
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while (1) {
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u64 largest_dl;
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l = left_child(idx);
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r = right_child(idx);
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largest = idx;
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largest_dl = orig_dl;
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if ((l < cp->size) && dl_time_before(orig_dl,
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cp->elements[l].dl)) {
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largest = l;
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largest_dl = cp->elements[l].dl;
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}
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if ((r < cp->size) && dl_time_before(largest_dl,
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cp->elements[r].dl))
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largest = r;
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if (largest == idx)
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break;
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/* pull largest child onto idx */
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cp->elements[idx].cpu = cp->elements[largest].cpu;
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cp->elements[idx].dl = cp->elements[largest].dl;
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cp->elements[cp->elements[idx].cpu].idx = idx;
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idx = largest;
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}
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/* actual push down of saved original values orig_* */
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cp->elements[idx].cpu = orig_cpu;
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cp->elements[idx].dl = orig_dl;
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cp->elements[cp->elements[idx].cpu].idx = idx;
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}
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static void cpudl_heapify_up(struct cpudl *cp, int idx)
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{
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int p;
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int orig_cpu = cp->elements[idx].cpu;
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u64 orig_dl = cp->elements[idx].dl;
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if (idx == 0)
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return;
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do {
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p = parent(idx);
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if (dl_time_before(orig_dl, cp->elements[p].dl))
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break;
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/* pull parent onto idx */
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cp->elements[idx].cpu = cp->elements[p].cpu;
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cp->elements[idx].dl = cp->elements[p].dl;
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cp->elements[cp->elements[idx].cpu].idx = idx;
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idx = p;
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} while (idx != 0);
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/* actual push up of saved original values orig_* */
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cp->elements[idx].cpu = orig_cpu;
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cp->elements[idx].dl = orig_dl;
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cp->elements[cp->elements[idx].cpu].idx = idx;
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}
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static void cpudl_heapify(struct cpudl *cp, int idx)
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{
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if (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
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cp->elements[idx].dl))
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cpudl_heapify_up(cp, idx);
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else
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cpudl_heapify_down(cp, idx);
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}
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static inline int cpudl_maximum(struct cpudl *cp)
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{
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return cp->elements[0].cpu;
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}
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/*
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* cpudl_find - find the best (later-dl) CPU in the system
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* @cp: the cpudl max-heap context
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* @p: the task
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* @later_mask: a mask to fill in with the selected CPUs (or NULL)
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*
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* Returns: int - CPUs were found
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*/
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int cpudl_find(struct cpudl *cp, struct task_struct *p,
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struct cpumask *later_mask)
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{
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const struct sched_dl_entity *dl_se = &p->dl;
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if (later_mask &&
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cpumask_and(later_mask, cp->free_cpus, p->cpus_ptr)) {
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return 1;
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} else {
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int best_cpu = cpudl_maximum(cp);
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WARN_ON(best_cpu != -1 && !cpu_present(best_cpu));
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if (cpumask_test_cpu(best_cpu, p->cpus_ptr) &&
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dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
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if (later_mask)
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cpumask_set_cpu(best_cpu, later_mask);
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return 1;
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}
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}
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return 0;
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}
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/*
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* cpudl_clear - remove a CPU from the cpudl max-heap
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* @cp: the cpudl max-heap context
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* @cpu: the target CPU
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*
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* Notes: assumes cpu_rq(cpu)->lock is locked
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*
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* Returns: (void)
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*/
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void cpudl_clear(struct cpudl *cp, int cpu)
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{
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int old_idx, new_cpu;
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unsigned long flags;
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WARN_ON(!cpu_present(cpu));
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raw_spin_lock_irqsave(&cp->lock, flags);
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old_idx = cp->elements[cpu].idx;
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if (old_idx == IDX_INVALID) {
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/*
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* Nothing to remove if old_idx was invalid.
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* This could happen if a rq_offline_dl is
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* called for a CPU without -dl tasks running.
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*/
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} else {
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new_cpu = cp->elements[cp->size - 1].cpu;
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cp->elements[old_idx].dl = cp->elements[cp->size - 1].dl;
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cp->elements[old_idx].cpu = new_cpu;
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cp->size--;
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cp->elements[new_cpu].idx = old_idx;
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cp->elements[cpu].idx = IDX_INVALID;
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cpudl_heapify(cp, old_idx);
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cpumask_set_cpu(cpu, cp->free_cpus);
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}
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raw_spin_unlock_irqrestore(&cp->lock, flags);
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}
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/*
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* cpudl_set - update the cpudl max-heap
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* @cp: the cpudl max-heap context
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* @cpu: the target CPU
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* @dl: the new earliest deadline for this CPU
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*
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* Notes: assumes cpu_rq(cpu)->lock is locked
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*
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* Returns: (void)
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*/
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void cpudl_set(struct cpudl *cp, int cpu, u64 dl)
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{
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int old_idx;
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unsigned long flags;
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WARN_ON(!cpu_present(cpu));
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raw_spin_lock_irqsave(&cp->lock, flags);
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old_idx = cp->elements[cpu].idx;
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if (old_idx == IDX_INVALID) {
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int new_idx = cp->size++;
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cp->elements[new_idx].dl = dl;
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cp->elements[new_idx].cpu = cpu;
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cp->elements[cpu].idx = new_idx;
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cpudl_heapify_up(cp, new_idx);
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cpumask_clear_cpu(cpu, cp->free_cpus);
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} else {
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cp->elements[old_idx].dl = dl;
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cpudl_heapify(cp, old_idx);
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}
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raw_spin_unlock_irqrestore(&cp->lock, flags);
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}
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/*
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* cpudl_set_freecpu - Set the cpudl.free_cpus
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* @cp: the cpudl max-heap context
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* @cpu: rd attached CPU
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*/
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void cpudl_set_freecpu(struct cpudl *cp, int cpu)
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{
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cpumask_set_cpu(cpu, cp->free_cpus);
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}
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/*
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* cpudl_clear_freecpu - Clear the cpudl.free_cpus
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* @cp: the cpudl max-heap context
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* @cpu: rd attached CPU
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*/
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void cpudl_clear_freecpu(struct cpudl *cp, int cpu)
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{
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cpumask_clear_cpu(cpu, cp->free_cpus);
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}
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/*
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* cpudl_init - initialize the cpudl structure
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* @cp: the cpudl max-heap context
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*/
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int cpudl_init(struct cpudl *cp)
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{
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int i;
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raw_spin_lock_init(&cp->lock);
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cp->size = 0;
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cp->elements = kcalloc(nr_cpu_ids,
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sizeof(struct cpudl_item),
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GFP_KERNEL);
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if (!cp->elements)
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return -ENOMEM;
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if (!zalloc_cpumask_var(&cp->free_cpus, GFP_KERNEL)) {
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kfree(cp->elements);
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return -ENOMEM;
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}
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for_each_possible_cpu(i)
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cp->elements[i].idx = IDX_INVALID;
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return 0;
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}
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/*
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* cpudl_cleanup - clean up the cpudl structure
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* @cp: the cpudl max-heap context
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*/
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void cpudl_cleanup(struct cpudl *cp)
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{
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free_cpumask_var(cp->free_cpus);
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kfree(cp->elements);
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}
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