ftrace: add tracing_cpumask
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 06380dc..18f0ab8 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -70,6 +70,23 @@
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)
{
/*
@@ -1754,9 +1771,49 @@
};
static struct file_operations show_traces_fops = {
- .open = show_traces_open,
- .read = seq_read,
- .release = seq_release,
+ .open = show_traces_open,
+ .read = seq_read,
+ .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
@@ -1837,9 +1894,9 @@
}
static struct file_operations tracing_iter_fops = {
- .open = tracing_open_generic,
- .read = tracing_iter_ctrl_read,
- .write = tracing_iter_ctrl_write,
+ .open = tracing_open_generic,
+ .read = tracing_iter_ctrl_read,
+ .write = tracing_iter_ctrl_write,
};
static const char readme_msg[] =
@@ -1870,8 +1927,8 @@
}
static struct file_operations tracing_readme_fops = {
- .open = tracing_open_generic,
- .read = tracing_readme_read,
+ .open = tracing_open_generic,
+ .read = tracing_readme_read,
};
static ssize_t
@@ -2334,6 +2391,11 @@
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)