Enable and disable osnoise/timerlat thread during on CPU hotplug online
and offline operations respectivelly.
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>
Cc: Clark Willaims <williams@xxxxxxxxxx>
Cc: John Kacur <jkacur@xxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: linux-doc@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
---
kernel/trace/trace_osnoise.c | 165 ++++++++++++++++++++++++++++-------
1 file changed, 135 insertions(+), 30 deletions(-)
diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index f4b1330ac89d..e8a63af1aeb6 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -1414,22 +1414,67 @@ static int timerlat_main(void *data)
#endif /* CONFIG_TIMERLAT_TRACER */
/*
- * stop_per_cpu_kthread - stop per-cpu threads
+ * stop_kthread - stop a workload thread
+ */
+static void stop_kthread(unsigned int cpu)
+{
+ struct task_struct *kthread;
+
+ kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread;
+ if (kthread)
+ kthread_stop(kthread);
+ per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
+}
+
+/*
+ * stop_per_cpu_kthread - Stop per-cpu threads
*
* Stop the osnoise sampling htread. Use this on unload and at system
* shutdown.
*/
static void stop_per_cpu_kthreads(void)
{
- struct task_struct *kthread;
int cpu;
- for_each_online_cpu(cpu) {
- kthread = per_cpu(per_cpu_osnoise_var, cpu).kthread;
- if (kthread)
- kthread_stop(kthread);
- per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
+ get_online_cpus();
+
+ for_each_online_cpu(cpu)
+ stop_kthread(cpu);
+
+ put_online_cpus();
+}
+
+/*
+ * start_kthread - Start a workload tread
+ */
+static int start_kthread(unsigned int cpu)
+{
+ struct task_struct *kthread;
+ void *main = osnoise_main;
+ char comm[24];
+
+#ifdef CONFIG_TIMERLAT_TRACER
+ if (osnoise_data.timerlat_tracer) {
+ snprintf(comm, 24, "timerlat/%d", cpu);
+ main = timerlat_main;
+ } else {
+ snprintf(comm, 24, "osnoise/%d", cpu);
}
+#else
+ snprintf(comm, 24, "osnoise/%d", cpu);
+#endif
+ kthread = kthread_create_on_cpu(main, NULL, cpu, comm);
+
+ if (IS_ERR(kthread)) {
+ pr_err(BANNER "could not start sampling thread\n");
+ stop_per_cpu_kthreads();
+ return -ENOMEM;
+ }
+
+ per_cpu(per_cpu_osnoise_var, cpu).kthread = kthread;
+ wake_up_process(kthread);
+
+ return 0;
}
/*
@@ -1441,9 +1486,7 @@ static void stop_per_cpu_kthreads(void)
static int start_per_cpu_kthreads(struct trace_array *tr)
{
struct cpumask *current_mask = &save_cpumask;
- struct task_struct *kthread;
- char comm[24];
- void *main = osnoise_main;
+ int retval;
int cpu;
get_online_cpus();
@@ -1455,37 +1498,91 @@ static int start_per_cpu_kthreads(struct trace_array *tr)
* And the CPU is online.
*/
cpumask_and(current_mask, cpu_online_mask, current_mask);
- put_online_cpus();
- for_each_online_cpu(cpu)
+ for_each_possible_cpu(cpu)
per_cpu(per_cpu_osnoise_var, cpu).kthread = NULL;
for_each_cpu(cpu, current_mask) {
-#ifdef CONFIG_TIMERLAT_TRACER
- if (osnoise_data.timerlat_tracer) {
- snprintf(comm, 24, "timerlat/%d", cpu);
- main = timerlat_main;
- } else {
- snprintf(comm, 24, "osnoise/%d", cpu);
- }
-#else
- snprintf(comm, 24, "osnoise/%d", cpu);
-#endif
- kthread = kthread_create_on_cpu(main, NULL, cpu, comm);
-
- if (IS_ERR(kthread)) {
- pr_err(BANNER "could not start sampling thread\n");
+ retval = start_kthread(cpu);
+ if (retval) {
stop_per_cpu_kthreads();
- return -ENOMEM;
+ return retval;
}
-
- per_cpu(per_cpu_osnoise_var, cpu).kthread = kthread;
- wake_up_process(kthread);
}
+ put_online_cpus();
+
return 0;
}
+#ifdef CONFIG_HOTPLUG_CPU
+static void osnoise_hotplug_workfn(struct work_struct *dummy)
+{
+ struct trace_array *tr = osnoise_trace;
+ unsigned int cpu = smp_processor_id();
+
+
+ mutex_lock(&trace_types_lock);
+
+ if (!osnoise_busy)
+ goto out_unlock_trace;
+
+ mutex_lock(&interface_lock);
+ get_online_cpus();
+
+ if (!cpumask_test_cpu(cpu, &osnoise_cpumask))
+ goto out_unlock;
+
+ if (!cpumask_test_cpu(cpu, tr->tracing_cpumask))
+ goto out_unlock;
+
+ start_kthread(cpu);
+
+out_unlock:
+ put_online_cpus();
+ mutex_unlock(&interface_lock);
+out_unlock_trace:
+ mutex_unlock(&trace_types_lock);
+}
+
+static DECLARE_WORK(osnoise_hotplug_work, osnoise_hotplug_workfn);
+
+/*
+ * osnoise_cpu_init - CPU hotplug online callback function
+ */
+static int osnoise_cpu_init(unsigned int cpu)
+{
+ schedule_work_on(cpu, &osnoise_hotplug_work);
+ return 0;
+}
+
+/*
+ * osnoise_cpu_die - CPU hotplug offline callback function
+ */
+static int osnoise_cpu_die(unsigned int cpu)
+{
+ stop_kthread(cpu);
+ return 0;
+}
+
+static void osnoise_init_hotplug_support(void)
+{
+ int ret;
+
+ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "trace/osnoise:online",
+ osnoise_cpu_init, osnoise_cpu_die);
+ if (ret < 0)
+ pr_warn(BANNER "Error to init cpu hotplug support\n");
+
+ return;
+}
+#else /* CONFIG_HOTPLUG_CPU */
+static void osnoise_init_hotplug_support(void)
+{
+ return 0;
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
/*
* osnoise_cpus_read - Read function for reading the "cpus" file
* @filp: The active open file structure
@@ -1581,7 +1678,14 @@ osnoise_cpus_write(struct file *filp, const char __user *ubuf, size_t count,
osnoise_tracer_stop(tr);
mutex_lock(&interface_lock);
+ /*
+ * osnoise_cpumask is read by CPU hotplug operations.
+ */
+ get_online_cpus();
+
cpumask_copy(&osnoise_cpumask, osnoise_cpumask_new);
+
+ put_online_cpus();
mutex_unlock(&interface_lock);
if (running)
@@ -1938,6 +2042,7 @@ __init static int init_osnoise_tracer(void)
return ret;
}
#endif
+ osnoise_init_hotplug_support();
init_tracefs();
--
2.31.1
