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Commit ee458aa7 authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware) Committed by Greg Kroah-Hartman
Browse files

tracing: Clean up the hwlat binding code 



[ Upstream commit f447c196fe7a3a92c6396f7628020cb8d564be15 ]

Instead of initializing the affinity of the hwlat kthread in the thread
itself, simply set up the initial affinity at thread creation. This
simplifies the code.

Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent b907dd1d

kernel/trace/trace_hwlat.c

+17 −17
Original line number Diff line number Diff line
@@ -268,24 +268,13 @@ static int get_sample(void) 
static struct cpumask save_cpumask;

static bool disable_migrate;



static void move_to_next_cpu(bool initmask)

static void move_to_next_cpu(void)

{

	static struct cpumask *current_mask;

	struct cpumask *current_mask = &save_cpumask;

	int next_cpu;



	if (disable_migrate)

		return;



	/* Just pick the first CPU on first iteration */

	if (initmask) {

		current_mask = &save_cpumask;

		get_online_cpus();

		cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);

		put_online_cpus();

		next_cpu = cpumask_first(current_mask);

		goto set_affinity;

	}



	/*

	 * If for some reason the user modifies the CPU affinity

	 * of this thread, than stop migrating for the duration
@@ -302,7 +291,6 @@ static void move_to_next_cpu(bool initmask) 
	if (next_cpu >= nr_cpu_ids)

		next_cpu = cpumask_first(current_mask);



 set_affinity:

	if (next_cpu >= nr_cpu_ids) /* Shouldn't happen! */

		goto disable;
@@ -332,12 +320,10 @@ static void move_to_next_cpu(bool initmask) 
static int kthread_fn(void *data)

{

	u64 interval;

	bool initmask = true;



	while (!kthread_should_stop()) {



		move_to_next_cpu(initmask);

		initmask = false;

		move_to_next_cpu();



		local_irq_disable();

		get_sample();
@@ -368,13 +354,27 @@ static int kthread_fn(void *data) 
 */

static int start_kthread(struct trace_array *tr)

{

	struct cpumask *current_mask = &save_cpumask;

	struct task_struct *kthread;

	int next_cpu;



	/* Just pick the first CPU on first iteration */

	current_mask = &save_cpumask;

	get_online_cpus();

	cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);

	put_online_cpus();

	next_cpu = cpumask_first(current_mask);



	kthread = kthread_create(kthread_fn, NULL, "hwlatd");

	if (IS_ERR(kthread)) {

		pr_err(BANNER "could not start sampling thread\n");

		return -ENOMEM;

	}



	cpumask_clear(current_mask);

	cpumask_set_cpu(next_cpu, current_mask);

	sched_setaffinity(kthread->pid, current_mask);



	hwlat_kthread = kthread;

	wake_up_process(kthread);