diff --git a/drivers/char/diag/diag_debugfs.c b/drivers/char/diag/diag_debugfs.c
index 62ef9acc1df3..c963e4658c07 100644
--- a/drivers/char/diag/diag_debugfs.c
+++ b/drivers/char/diag/diag_debugfs.c
@@ -276,8 +276,10 @@ static ssize_t diag_dbgfs_read_table(struct file *file, char __user *ubuf,
 	struct list_head *temp;
 	struct diag_cmd_reg_t *item = NULL;
 
+	mutex_lock(&driver->cmd_reg_mutex);
 	if (diag_dbgfs_table_index == driver->cmd_reg_count) {
 		diag_dbgfs_table_index = 0;
+		mutex_unlock(&driver->cmd_reg_mutex);
 		return 0;
 	}
 
@@ -286,6 +288,7 @@ static ssize_t diag_dbgfs_read_table(struct file *file, char __user *ubuf,
 	buf = kzalloc(sizeof(char) * buf_size, GFP_KERNEL);
 	if (ZERO_OR_NULL_PTR(buf)) {
 		pr_err("diag: %s, Error allocating memory\n", __func__);
+		mutex_unlock(&driver->cmd_reg_mutex);
 		return -ENOMEM;
 	}
 	buf_size = ksize(buf);
@@ -330,6 +333,7 @@ static ssize_t diag_dbgfs_read_table(struct file *file, char __user *ubuf,
 			break;
 	}
 	diag_dbgfs_table_index = i;
+	mutex_unlock(&driver->cmd_reg_mutex);
 
 	*ppos = 0;
 	ret = simple_read_from_buffer(ubuf, count, ppos, buf, bytes_in_buffer);