From e1c08bdd9fa73e44096e5a82c0d5928b04ab02c8 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <srostedt@redhat.com>
Date: Mon, 12 May 2008 21:20:44 +0200
Subject: ftrace: force recording
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/trace/ftrace.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)
(limited to 'kernel/trace')
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 97d5cb7..4facf5c 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -146,6 +146,10 @@ static int notrace __unregister_ftrace_function(struct ftrace_ops *ops)
#ifdef CONFIG_DYNAMIC_FTRACE
+static struct task_struct *ftraced_task;
+static DECLARE_WAIT_QUEUE_HEAD(ftraced_waiters);
+static unsigned long ftraced_iteration_counter;
+
enum {
FTRACE_ENABLE_CALLS = (1 << 0),
FTRACE_DISABLE_CALLS = (1 << 1),
@@ -590,9 +594,12 @@ static int notrace ftraced(void *ignore)
ftraced_trigger = 0;
ftrace_record_suspend--;
}
+ ftraced_iteration_counter++;
mutex_unlock(&ftraced_lock);
mutex_unlock(&ftrace_sysctl_lock);
+ wake_up_interruptible(&ftraced_waiters);
+
ftrace_shutdown_replenish();
set_current_state(TASK_INTERRUPTIBLE);
@@ -1050,6 +1057,49 @@ static struct file_operations ftrace_filter_fops = {
.release = ftrace_filter_release,
};
+/**
+ * ftrace_force_update - force an update to all recording ftrace functions
+ *
+ * The ftrace dynamic update daemon only wakes up once a second.
+ * There may be cases where an update needs to be done immediately
+ * for tests or internal kernel tracing to begin. This function
+ * wakes the daemon to do an update and will not return until the
+ * update is complete.
+ */
+int ftrace_force_update(void)
+{
+ unsigned long last_counter;
+ DECLARE_WAITQUEUE(wait, current);
+ int ret = 0;
+
+ if (!ftraced_task)
+ return -ENODEV;
+
+ mutex_lock(&ftraced_lock);
+ last_counter = ftraced_iteration_counter;
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ add_wait_queue(&ftraced_waiters, &wait);
+
+ do {
+ mutex_unlock(&ftraced_lock);
+ wake_up_process(ftraced_task);
+ schedule();
+ mutex_lock(&ftraced_lock);
+ if (signal_pending(current)) {
+ ret = -EINTR;
+ break;
+ }
+ set_current_state(TASK_INTERRUPTIBLE);
+ } while (last_counter == ftraced_iteration_counter);
+
+ mutex_unlock(&ftraced_lock);
+ remove_wait_queue(&ftraced_waiters, &wait);
+ set_current_state(TASK_RUNNING);
+
+ return ret;
+}
+
static __init int ftrace_init_debugfs(void)
{
struct dentry *d_tracer;
@@ -1095,6 +1145,7 @@ static int __init notrace ftrace_dynamic_init(void)
return -1;
last_ftrace_enabled = ftrace_enabled = 1;
+ ftraced_task = p;
return 0;
}
--
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