ftrace: make use of 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 18f0ab8..3ae17e2 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -70,23 +70,6 @@
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)
{
/*
@@ -1776,19 +1759,46 @@
.release = seq_release,
};
+/*
+ * Only trace on a CPU if the bitmask is set:
+ */
+static cpumask_t tracing_cpumask = CPU_MASK_ALL;
+
+/*
+ * When tracing/tracing_cpu_mask is modified then this holds
+ * the new bitmask we are about to install:
+ */
+static cpumask_t tracing_cpumask_new;
+
+/*
+ * 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 (and one more byte for the newline):
+ */
+static char mask_str[NR_CPUS + 1];
+
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);
+ int len;
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;
+
+ len = cpumask_scnprintf(mask_str, count, tracing_cpumask);
+ if (count - len < 2) {
+ count = -EINVAL;
+ goto out_err;
+ }
+ len += sprintf(mask_str + len, "\n");
+ count = simple_read_from_buffer(ubuf, count, ppos, mask_str, NR_CPUS+1);
+
+out_err:
mutex_unlock(&tracing_cpumask_update_lock);
return count;
@@ -1798,16 +1808,40 @@
tracing_cpumask_write(struct file *filp, const char __user *ubuf,
size_t count, loff_t *ppos)
{
- int err;
+ int err, cpu;
mutex_lock(&tracing_cpumask_update_lock);
- err = cpumask_parse_user(ubuf, count, tracing_cpumask);
+ err = cpumask_parse_user(ubuf, count, tracing_cpumask_new);
+ if (err)
+ goto err_unlock;
+
+ spin_lock_irq(&ftrace_max_lock);
+ for_each_possible_cpu(cpu) {
+ /*
+ * Increase/decrease the disabled counter if we are
+ * about to flip a bit in the cpumask:
+ */
+ if (cpu_isset(cpu, tracing_cpumask) &&
+ !cpu_isset(cpu, tracing_cpumask_new)) {
+ atomic_inc(&global_trace.data[cpu]->disabled);
+ }
+ if (!cpu_isset(cpu, tracing_cpumask) &&
+ cpu_isset(cpu, tracing_cpumask_new)) {
+ atomic_dec(&global_trace.data[cpu]->disabled);
+ }
+ }
+ spin_unlock_irq(&ftrace_max_lock);
+
+ tracing_cpumask = tracing_cpumask_new;
+
mutex_unlock(&tracing_cpumask_update_lock);
- if (err)
- return err;
-
return count;
+
+err_unlock:
+ mutex_unlock(&tracing_cpumask_update_lock);
+
+ return err;
}
static struct file_operations tracing_cpumask_fops = {
@@ -1846,8 +1880,7 @@
r += sprintf(buf + r, "\n");
WARN_ON(r >= len + 2);
- r = simple_read_from_buffer(ubuf, cnt, ppos,
- buf, r);
+ r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
kfree(buf);