ftrace: add tracing_cpumask (c7078de1) · Commits · e / devices / android_kernel_xiaomi_markw

kernel/trace/trace.c

+70 −8

Original line number	Diff line number	Diff line
		@@ -70,6 +70,23 @@ static DECLARE_WAIT_QUEUE_HEAD(trace_wait);

		unsigned long trace_flags = TRACE_ITER_PRINT_PARENT;

		/*
		* Only trace on a CPU if the bitmask is set:
		*/
		static cpumask_t tracing_cpumask __read_mostly = CPU_MASK_ALL;

		/*
		* The tracer itself will not take this lock, but still we want
		* to provide a consistent cpumask to user-space:
		*/
		static DEFINE_MUTEX(tracing_cpumask_update_lock);

		/*
		* Temporary storage for the character representation of the
		* CPU bitmask:
		*/
		static char mask_str[NR_CPUS];

		void trace_wake_up(void)
		{
		/*
		@@ -1759,6 +1776,46 @@ static struct file_operations show_traces_fops = {
		.release = seq_release,
		};

		static ssize_t
		tracing_cpumask_read(struct file filp, char __user ubuf,
		size_t count, loff_t *ppos)
		{
		int err;

		count = min(count, (size_t)NR_CPUS);

		mutex_lock(&tracing_cpumask_update_lock);
		cpumask_scnprintf(mask_str, NR_CPUS, tracing_cpumask);
		err = copy_to_user(ubuf, mask_str, count);
		if (err)
		count = -EFAULT;
		mutex_unlock(&tracing_cpumask_update_lock);

		return count;
		}

		static ssize_t
		tracing_cpumask_write(struct file filp, const char __user ubuf,
		size_t count, loff_t *ppos)
		{
		int err;

		mutex_lock(&tracing_cpumask_update_lock);
		err = cpumask_parse_user(ubuf, count, tracing_cpumask);
		mutex_unlock(&tracing_cpumask_update_lock);

		if (err)
		return err;

		return count;
		}

		static struct file_operations tracing_cpumask_fops = {
		.open = tracing_open_generic,
		.read = tracing_cpumask_read,
		.write = tracing_cpumask_write,
		};

		static ssize_t
		tracing_iter_ctrl_read(struct file filp, char __user ubuf,
		size_t cnt, loff_t *ppos)
		@@ -2334,6 +2391,11 @@ static __init void tracer_init_debugfs(void)
		if (!entry)
		pr_warning("Could not create debugfs 'iter_ctrl' entry\n");

		entry = debugfs_create_file("tracing_cpumask", 0644, d_tracer,
		NULL, &tracing_cpumask_fops);
		if (!entry)
		pr_warning("Could not create debugfs 'tracing_cpumask' entry\n");

		entry = debugfs_create_file("latency_trace", 0444, d_tracer,
		&global_trace, &tracing_lt_fops);
		if (!entry)