[PATCH] pstore/ftrace: add a kernel parameter to start pstore recording

[Uwe Kleine-König]

With this knob you can enable pstore recording early enough to debug
hangs happening during the boot process before userspace is up enough to
enable it via sysfs.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
---
 fs/pstore/ftrace.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/fs/pstore/ftrace.c b/fs/pstore/ftrace.c
index 5939595f0115..92d35ee83c95 100644
--- a/fs/pstore/ftrace.c
+++ b/fs/pstore/ftrace.c
@@ -117,13 +117,26 @@ static const struct file_operations pstore_knob_fops = {
 
 static struct dentry *pstore_ftrace_dir;
 
+static unsigned int record_ftrace_init;
+module_param(record_ftrace_init, uint, 0400);
+
 void pstore_register_ftrace(void)
 {
+	int ret;
+
 	if (!psinfo->write)
 		return;
 
 	pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
 
+	if (record_ftrace_init) {
+		ret = register_ftrace_function(&pstore_ftrace_ops);
+		if (ret)
+			return;
+
+		pstore_ftrace_enabled = 1;
+	}
+
 	debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL,
 			    &pstore_knob_fops);
 }
-- 
2.29.2