1 files changed, 30 insertions, 16 deletions

diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c
index 5939595f0115..776cae20af4e 100644
--- a/fs/pstore/ftrace.c
+++ b/fs/pstore/ftrace.c
@@ -64,20 +64,12 @@ static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
 static DEFINE_MUTEX(pstore_ftrace_lock);
 static bool pstore_ftrace_enabled;
 
-static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
-					size_t count, loff_t *ppos)
+static int pstore_set_ftrace_enabled(bool on)
 {
-	u8 on;
 	ssize_t ret;
 
-	ret = kstrtou8_from_user(buf, count, 2, &on);
-	if (ret)
-		return ret;
-
-	mutex_lock(&pstore_ftrace_lock);
-
-	if (!on ^ pstore_ftrace_enabled)
-		goto out;
+	if (on == pstore_ftrace_enabled)
+		return 0;
 
 	if (on) {
 		ftrace_ops_set_global_filter(&pstore_ftrace_ops);
@@ -89,15 +81,30 @@ static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
 	if (ret) {
 		pr_err("%s: unable to %sregister ftrace ops: %zd\n",
 		       __func__, on ? "" : "un", ret);
-		goto err;
+	} else {
+		pstore_ftrace_enabled = on;
 	}
 
-	pstore_ftrace_enabled = on;
-out:
-	ret = count;
-err:
+	return ret;
+}
+
+static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
+					size_t count, loff_t *ppos)
+{
+	u8 on;
+	ssize_t ret;
+
+	ret = kstrtou8_from_user(buf, count, 2, &on);
+	if (ret)
+		return ret;
+
+	mutex_lock(&pstore_ftrace_lock);
+	ret = pstore_set_ftrace_enabled(on);
 	mutex_unlock(&pstore_ftrace_lock);
 
+	if (ret == 0)
+		ret = count;
+
 	return ret;
 }
 
@@ -117,6 +124,11 @@ static const struct file_operations pstore_knob_fops = {
 
 static struct dentry *pstore_ftrace_dir;
 
+static bool record_ftrace;
+module_param(record_ftrace, bool, 0400);
+MODULE_PARM_DESC(record_ftrace,
+		 "enable ftrace recording immediately (default: off)");
+
 void pstore_register_ftrace(void)
 {
 	if (!psinfo->write)
@@ -124,6 +136,8 @@ void pstore_register_ftrace(void)
 
 	pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
 
+	pstore_set_ftrace_enabled(record_ftrace);
+
 	debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL,
 			    &pstore_knob_fops);
 }