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dyndbg: add test_dynamic_debug module

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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>
This commit is contained in:
Jim Cromie
2022-09-04 15:40:45 -06:00
committed by Greg Kroah-Hartman
parent e75ef56f74
commit 683263a5e0
4 changed files with 83 additions and 0 deletions
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70
lib/test_dynamic_debug.c Normal file
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@@ -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");