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cpuset: Cleanup cpuset_cpus_allowed_fallback() use in select_fallback_rq()
select_fallback_rq() only needs to recheck for an allowed CPU if the affinity mask of the task has changed since the last check. Return a 'bool' from cpuset_cpus_allowed_fallback() to indicate whether the affinity mask was updated, and use this to elide the allowed check when the mask has been left alone. No functional change. Suggested-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> Link: https://lore.kernel.org/r/20210730112443.23245-5-will@kernel.org
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@ -59,7 +59,7 @@ extern void cpuset_wait_for_hotplug(void);
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extern void cpuset_read_lock(void);
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extern void cpuset_read_unlock(void);
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extern void cpuset_cpus_allowed(struct task_struct *p, struct cpumask *mask);
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extern void cpuset_cpus_allowed_fallback(struct task_struct *p);
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extern bool cpuset_cpus_allowed_fallback(struct task_struct *p);
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extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
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#define cpuset_current_mems_allowed (current->mems_allowed)
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void cpuset_init_current_mems_allowed(void);
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@ -188,8 +188,9 @@ static inline void cpuset_cpus_allowed(struct task_struct *p,
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cpumask_copy(mask, task_cpu_possible_mask(p));
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}
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static inline void cpuset_cpus_allowed_fallback(struct task_struct *p)
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static inline bool cpuset_cpus_allowed_fallback(struct task_struct *p)
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{
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return false;
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}
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static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
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@ -3327,17 +3327,22 @@ void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
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* which will not contain a sane cpumask during cases such as cpu hotplugging.
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* This is the absolute last resort for the scheduler and it is only used if
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* _every_ other avenue has been traveled.
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*
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* Returns true if the affinity of @tsk was changed, false otherwise.
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**/
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void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
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bool cpuset_cpus_allowed_fallback(struct task_struct *tsk)
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{
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const struct cpumask *possible_mask = task_cpu_possible_mask(tsk);
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const struct cpumask *cs_mask;
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bool changed = false;
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rcu_read_lock();
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cs_mask = task_cs(tsk)->cpus_allowed;
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if (is_in_v2_mode() && cpumask_subset(cs_mask, possible_mask))
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if (is_in_v2_mode() && cpumask_subset(cs_mask, possible_mask)) {
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do_set_cpus_allowed(tsk, cs_mask);
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changed = true;
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}
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rcu_read_unlock();
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/*
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@ -3357,6 +3362,7 @@ void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
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* select_fallback_rq() will fix things ups and set cpu_possible_mask
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* if required.
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*/
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return changed;
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}
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void __init cpuset_init_current_mems_allowed(void)
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@ -3141,8 +3141,7 @@ static int select_fallback_rq(int cpu, struct task_struct *p)
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/* No more Mr. Nice Guy. */
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switch (state) {
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case cpuset:
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if (IS_ENABLED(CONFIG_CPUSETS)) {
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cpuset_cpus_allowed_fallback(p);
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if (cpuset_cpus_allowed_fallback(p)) {
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state = possible;
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break;
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}
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