From 683263a5e075aca81915a5abc0006a5435d3d54d Mon Sep 17 00:00:00 2001
From: Jim Cromie <jim.cromie@gmail.com>
Date: Sun, 4 Sep 2022 15:40:45 -0600
Subject: dyndbg: add test_dynamic_debug module

Provide a simple module to allow testing DYNAMIC_DEBUG behavior.  It
calls do_prints() from module-init, and with a sysfs-node.

  dmesg -C
  dmesg -w &
  modprobe test_dynamic_debug dyndbg=+p
  echo 1 > /sys/module/dynamic_debug/parameters/verbose

  cat /sys/module/test_dynamic_debug/parameters/do_prints
  echo module test_dynamic_debug +mftl > /proc/dynamic_debug/control
  echo junk > /sys/module/test_dynamic_debug/parameters/do_prints

Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-9-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 lib/test_dynamic_debug.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 lib/test_dynamic_debug.c

(limited to 'lib/test_dynamic_debug.c')

diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c
new file mode 100644
index 000000000000..ba3882ca3e48
--- /dev/null
+++ b/lib/test_dynamic_debug.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Kernel module for testing dynamic_debug
+ *
+ * Authors:
+ *      Jim Cromie	<jim.cromie@gmail.com>
+ */
+
+#define pr_fmt(fmt) "test_dd: " fmt
+
+#include <linux/module.h>
+
+static void do_prints(void); /* device under test */
+
+/* run tests by reading or writing sysfs node */
+
+static int param_set_do_prints(const char *instr, const struct kernel_param *kp)
+{
+	do_prints();
+	return 0;
+}
+
+static int param_get_do_prints(char *buffer, const struct kernel_param *kp)
+{
+	do_prints();
+	return scnprintf(buffer, PAGE_SIZE, "did do_prints\n");
+}
+
+static const struct kernel_param_ops param_ops_do_prints = {
+	.set = param_set_do_prints,
+	.get = param_get_do_prints,
+};
+
+module_param_cb(do_prints, &param_ops_do_prints, NULL, 0600);
+
+static void do_alpha(void)
+{
+	pr_debug("do alpha\n");
+}
+static void do_beta(void)
+{
+	pr_debug("do beta\n");
+}
+
+static void do_prints(void)
+{
+	do_alpha();
+	do_beta();
+}
+
+static int __init test_dynamic_debug_init(void)
+{
+	pr_debug("init start\n");
+
+	do_prints();
+
+	pr_debug("init done\n");
+	return 0;
+}
+
+static void __exit test_dynamic_debug_exit(void)
+{
+	pr_debug("exiting\n");
+}
+
+module_init(test_dynamic_debug_init);
+module_exit(test_dynamic_debug_exit);
+
+MODULE_AUTHOR("Jim Cromie <jim.cromie@gmail.com>");
+MODULE_LICENSE("GPL");
-- 
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