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sched/core: Check for available DL bandwidth in cpuset_cpu_inactive()
Hotplug operations are destructive w.r.t. cpusets. In case such an operation is performed on a CPU belonging to an exlusive cpuset, the DL bandwidth information associated with the corresponding root domain is gone even if the operation fails (in sched_cpu_inactive()). For this reason we need to move the check we currently have in sched_cpu_inactive() to cpuset_cpu_inactive() to prevent useless cpusets reconfiguration in the CPU_DOWN_FAILED path. Signed-off-by: Juri Lelli <juri.lelli@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@gmail.com> Link: http://lkml.kernel.org/r/1427792017-7356-2-git-send-email-juri.lelli@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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4cd57f9713
commit
3c18d447b3
1 changed files with 28 additions and 28 deletions
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@ -5337,36 +5337,13 @@ static int sched_cpu_active(struct notifier_block *nfb,
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static int sched_cpu_inactive(struct notifier_block *nfb,
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unsigned long action, void *hcpu)
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{
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unsigned long flags;
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long cpu = (long)hcpu;
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struct dl_bw *dl_b;
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switch (action & ~CPU_TASKS_FROZEN) {
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case CPU_DOWN_PREPARE:
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set_cpu_active(cpu, false);
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/* explicitly allow suspend */
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if (!(action & CPU_TASKS_FROZEN)) {
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bool overflow;
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int cpus;
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rcu_read_lock_sched();
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dl_b = dl_bw_of(cpu);
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raw_spin_lock_irqsave(&dl_b->lock, flags);
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cpus = dl_bw_cpus(cpu);
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overflow = __dl_overflow(dl_b, cpus, 0, 0);
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raw_spin_unlock_irqrestore(&dl_b->lock, flags);
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rcu_read_unlock_sched();
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if (overflow)
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return notifier_from_errno(-EBUSY);
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}
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set_cpu_active((long)hcpu, false);
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return NOTIFY_OK;
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default:
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return NOTIFY_DONE;
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}
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return NOTIFY_DONE;
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}
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static int __init migration_init(void)
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@ -7006,7 +6983,6 @@ static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
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*/
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case CPU_ONLINE:
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case CPU_DOWN_FAILED:
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cpuset_update_active_cpus(true);
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break;
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default:
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@ -7018,8 +6994,32 @@ static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,
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static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action,
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void *hcpu)
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{
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switch (action) {
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unsigned long flags;
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long cpu = (long)hcpu;
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struct dl_bw *dl_b;
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switch (action & ~CPU_TASKS_FROZEN) {
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case CPU_DOWN_PREPARE:
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/* explicitly allow suspend */
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if (!(action & CPU_TASKS_FROZEN)) {
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bool overflow;
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int cpus;
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rcu_read_lock_sched();
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dl_b = dl_bw_of(cpu);
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raw_spin_lock_irqsave(&dl_b->lock, flags);
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cpus = dl_bw_cpus(cpu);
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overflow = __dl_overflow(dl_b, cpus, 0, 0);
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raw_spin_unlock_irqrestore(&dl_b->lock, flags);
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rcu_read_unlock_sched();
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if (overflow) {
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trace_printk("hotplug failed for cpu %lu", cpu);
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return notifier_from_errno(-EBUSY);
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}
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}
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cpuset_update_active_cpus(false);
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break;
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case CPU_DOWN_PREPARE_FROZEN:
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