rk3568 rt init

hc

2023-11-06 e3e12f52b214121840b44c91de5b3e5af5d3eb84

 kernel/kernel/cpu.c
..
..
@@ -876,6 +876,15 @@
876
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 	int err, cpu = smp_processor_id();
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 	int ret;
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878
 
879
+#ifdef CONFIG_PREEMPT_RT_BASE
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+	/*
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+	 * If any tasks disabled migration before we got here,
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+	 * go back and sleep again.
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+	 */
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+	if (cpu_nr_pinned(cpu))
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+		return -EAGAIN;
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+#endif
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+
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 	/* Ensure this CPU doesn't handle any more interrupts. */
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 	err = __cpu_disable();
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 	if (err < 0)
..
..
@@ -903,6 +912,10 @@
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 	return 0;
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 }
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914
 
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+#ifdef CONFIG_PREEMPT_RT_BASE
916
+struct task_struct *takedown_cpu_task;
917
+#endif
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+
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 static int takedown_cpu(unsigned int cpu)
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 {
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 	struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
..
..
@@ -917,11 +930,39 @@
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 	 */
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 	irq_lock_sparse();
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932
 
933
+#ifdef CONFIG_PREEMPT_RT_BASE
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+	WARN_ON_ONCE(takedown_cpu_task);
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+	takedown_cpu_task = current;
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+
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+again:
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+	/*
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+	 * If a task pins this CPU after we pass this check, take_cpu_down
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+	 * will return -EAGAIN.
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+	 */
942
+	for (;;) {
943
+		int nr_pinned;
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+
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+		set_current_state(TASK_UNINTERRUPTIBLE);
946
+		nr_pinned = cpu_nr_pinned(cpu);
947
+		if (nr_pinned == 0)
948
+			break;
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+		schedule();
950
+	}
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+	set_current_state(TASK_RUNNING);
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+#endif
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+
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 	/*
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 	 * So now all preempt/rcu users must observe !cpu_active().
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 	 */
923
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 	err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu));
958
+#ifdef CONFIG_PREEMPT_RT_BASE
959
+	if (err == -EAGAIN)
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+		goto again;
961
+#endif
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 	if (err) {
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+#ifdef CONFIG_PREEMPT_RT_BASE
964
+		takedown_cpu_task = NULL;
965
+#endif
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966
 		/* CPU refused to die */
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 		irq_unlock_sparse();
927
968
 		/* Unpark the hotplug thread so we can rollback there */
..
..
@@ -940,6 +981,9 @@
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 	wait_for_ap_thread(st, false);
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 	BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
942
983
 
984
+#ifdef CONFIG_PREEMPT_RT_BASE
985
+	takedown_cpu_task = NULL;
986
+#endif
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 	/* Interrupts are moved away from the dying cpu, reenable alloc/free */
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 	irq_unlock_sparse();
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989