trace/osnoise: Support hotplug operations
Enable and disable osnoise/timerlat thread during on CPU hotplug online and offline operations respectivelly. Link: https://lore.kernel.org/linux-doc/20210621134636.5b332226@oasis.local.home/ Link: https://lkml.kernel.org/r/39f98590b3caeb3c32f09526214058efe0e9272a.1624372313.git.bristot@redhat.com Cc: Phil Auld <pauld@redhat.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Kate Carcia <kcarcia@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Alexandre Chartre <alexandre.chartre@oracle.com> Cc: Clark Willaims <williams@redhat.com> Cc: John Kacur <jkacur@redhat.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Suggested-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Daniel Bristot de Oliveira
Steven Rostedt (VMware)
Родитель
ba998f7d95
Коммит
c8895e271f
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@ -1416,22 +1416,67 @@ static int timerlat_main(void *data)
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#endif /* CONFIG_TIMERLAT_TRACER */
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/*
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* stop_per_cpu_kthread - stop per-cpu threads
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* stop_kthread - stop a workload thread
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*/
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static void stop_kthread(unsigned int cpu)
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{
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struct task_struct *kthread;
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kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread;
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if (kthread)
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kthread_stop(kthread);
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per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
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}
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/*
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* stop_per_cpu_kthread - Stop per-cpu threads
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*
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* Stop the osnoise sampling htread. Use this on unload and at system
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* shutdown.
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*/
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static void stop_per_cpu_kthreads(void)
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{
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struct task_struct *kthread;
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int cpu;
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for_each_online_cpu(cpu) {
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kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread;
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if (kthread)
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kthread_stop(kthread);
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per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
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get_online_cpus();
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for_each_online_cpu(cpu)
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stop_kthread(cpu);
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put_online_cpus();
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}
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/*
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* start_kthread - Start a workload tread
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*/
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static int start_kthread(unsigned int cpu)
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{
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struct task_struct *kthread;
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void *main = osnoise_main;
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char comm[24];
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#ifdef CONFIG_TIMERLAT_TRACER
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if (osnoise_data.timerlat_tracer) {
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snprintf(comm, 24, "timerlat/%d", cpu);
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main = timerlat_main;
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} else {
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snprintf(comm, 24, "osnoise/%d", cpu);
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}
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#else
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snprintf(comm, 24, "osnoise/%d", cpu);
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#endif
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kthread = kthread_create_on_cpu(main, NULL, cpu, comm);
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if (IS_ERR(kthread)) {
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pr_err(BANNER "could not start sampling thread\n");
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stop_per_cpu_kthreads();
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return -ENOMEM;
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}
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per_cpu(per_cpu_osnoise_var, cpu).kthread = kthread;
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wake_up_process(kthread);
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return 0;
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}
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/*
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@ -1443,9 +1488,7 @@ static void stop_per_cpu_kthreads(void)
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static int start_per_cpu_kthreads(struct trace_array *tr)
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{
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struct cpumask *current_mask = &save_cpumask;
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struct task_struct *kthread;
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char comm[24];
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void *main = osnoise_main;
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int retval;
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int cpu;
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get_online_cpus();
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@ -1457,37 +1500,91 @@ static int start_per_cpu_kthreads(struct trace_array *tr)
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* And the CPU is online.
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*/
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cpumask_and(current_mask, cpu_online_mask, current_mask);
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put_online_cpus();
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for_each_online_cpu(cpu)
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for_each_possible_cpu(cpu)
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per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
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for_each_cpu(cpu, current_mask) {
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#ifdef CONFIG_TIMERLAT_TRACER
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if (osnoise_data.timerlat_tracer) {
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snprintf(comm, 24, "timerlat/%d", cpu);
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main = timerlat_main;
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} else {
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snprintf(comm, 24, "osnoise/%d", cpu);
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}
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#else
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snprintf(comm, 24, "osnoise/%d", cpu);
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#endif
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kthread = kthread_create_on_cpu(main, NULL, cpu, comm);
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if (IS_ERR(kthread)) {
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pr_err(BANNER "could not start sampling thread\n");
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retval = start_kthread(cpu);
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if (retval) {
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stop_per_cpu_kthreads();
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return -ENOMEM;
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return retval;
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}
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per_cpu(per_cpu_osnoise_var, cpu).kthread = kthread;
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wake_up_process(kthread);
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}
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put_online_cpus();
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return 0;
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}
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#ifdef CONFIG_HOTPLUG_CPU
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static void osnoise_hotplug_workfn(struct work_struct *dummy)
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{
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struct trace_array *tr = osnoise_trace;
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unsigned int cpu = smp_processor_id();
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mutex_lock(&trace_types_lock);
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if (!osnoise_busy)
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goto out_unlock_trace;
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mutex_lock(&interface_lock);
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get_online_cpus();
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if (!cpumask_test_cpu(cpu, &osnoise_cpumask))
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goto out_unlock;
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if (!cpumask_test_cpu(cpu, tr->tracing_cpumask))
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goto out_unlock;
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start_kthread(cpu);
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out_unlock:
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put_online_cpus();
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mutex_unlock(&interface_lock);
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out_unlock_trace:
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mutex_unlock(&trace_types_lock);
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}
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static DECLARE_WORK(osnoise_hotplug_work, osnoise_hotplug_workfn);
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/*
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* osnoise_cpu_init - CPU hotplug online callback function
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*/
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static int osnoise_cpu_init(unsigned int cpu)
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{
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schedule_work_on(cpu, &osnoise_hotplug_work);
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return 0;
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}
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/*
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* osnoise_cpu_die - CPU hotplug offline callback function
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*/
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static int osnoise_cpu_die(unsigned int cpu)
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{
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stop_kthread(cpu);
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return 0;
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}
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static void osnoise_init_hotplug_support(void)
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{
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int ret;
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ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "trace/osnoise:online",
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osnoise_cpu_init, osnoise_cpu_die);
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if (ret < 0)
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pr_warn(BANNER "Error to init cpu hotplug support\n");
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return;
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}
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#else /* CONFIG_HOTPLUG_CPU */
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static void osnoise_init_hotplug_support(void)
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{
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return 0;
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}
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#endif /* CONFIG_HOTPLUG_CPU */
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/*
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* osnoise_cpus_read - Read function for reading the "cpus" file
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* @filp: The active open file structure
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@ -1583,7 +1680,14 @@ osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
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osnoise_tracer_stop(tr);
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mutex_lock(&interface_lock);
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/*
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* osnoise_cpumask is read by CPU hotplug operations.
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*/
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get_online_cpus();
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cpumask_copy(&osnoise_cpumask, osnoise_cpumask_new);
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put_online_cpus();
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mutex_unlock(&interface_lock);
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if (running)
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@ -1940,6 +2044,7 @@ __init static int init_osnoise_tracer(void)
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return ret;
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}
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#endif
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osnoise_init_hotplug_support();
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init_tracefs();
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