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>

diff --git a/MAINTAINERS b/MAINTAINERS
index 9d7f64dc0efe81bce57b80ef78ef9affe86b2c36..8d8f99a5c2791864ce40e2cc4ef854bc5bd3a05f 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7205,6 +7205,8 @@ M:        Jason Baron <jbaron@akamai.com>
 S:     Maintained
 F:     include/linux/dynamic_debug.h
 F:     lib/dynamic_debug.c
+M:     Jim Cromie <jim.cromie@gmail.com>
+F:     lib/test_dynamic_debug.c
 
 DYNAMIC INTERRUPT MODERATION
 M:     Tal Gilboa <talgi@nvidia.com>

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 072e4b289c13e2b312000092b59e12868c7cf301..43b49642cb08c6e845e3c3ca9e6765de49b4191d 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2546,6 +2546,16 @@ config TEST_STATIC_KEYS
 
          If unsure, say N.
 
+config TEST_DYNAMIC_DEBUG
+       tristate "Test DYNAMIC_DEBUG"
+       depends on DYNAMIC_DEBUG
+       help
+         This module registers a tracer callback to count enabled
+         pr_debugs in a 'do_debugging' function, then alters their
+         enablements, calls the function, and compares counts.
+
+         If unsure, say N.
+
 config TEST_KMOD
        tristate "kmod stress tester"
        depends on m

diff --git a/lib/Makefile b/lib/Makefile
index 5927d7fa08063dec069e64a7e469e7fc9dcf333c..338036b0b80c14f2fbe6d0b578653d539605e8fa 100644 (file)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -82,6 +82,7 @@ obj-$(CONFIG_TEST_SORT) += test_sort.o
 obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
 obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
 obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
+obj-$(CONFIG_TEST_DYNAMIC_DEBUG) += test_dynamic_debug.o
 obj-$(CONFIG_TEST_PRINTF) += test_printf.o
 obj-$(CONFIG_TEST_SCANF) += test_scanf.o
 obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o

diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c
new file mode 100644 (file)
index 0000000..ba3882c
--- /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");