linux-kernel - [PATCH] hangcheck-timer: use pr

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Message-Id: <20251105140541.9658-1-clintbgeorge@gmail.com>
Date: Wed,  5 Nov 2025 19:35:41 +0530
From: Clint George <clintbgeorge@...il.com>
To: arnd@...db.de,
	gregkh@...uxfoundation.org
Cc: linux-kernel-mentees@...ts.linux.dev,
	skhan@...uxfoundation.org,
	khalid@...nel.org,
	david.hunter.linux@...il.com,
	linux-kernel@...r.kernel.org,
	Clint George <clintbgeorge@...il.com>
Subject: [PATCH] hangcheck-timer: use pr_crit and fix coding style

Fix coding style issues and improve logging in hangcheck-timer such as replace printk(KERN_CRIT ...) to pr_crit(...) where applicable and replace non-standard %Ld with %lld in debug prints and use proper pr_debug/pr_crit for kernel logging.

No functional changes were made to hangcheck logic.

Signed-off-by: Clint George <clintbgeorge@...il.com>
---

Testing:
- Verified timer firing and margin detection using "hangtest" module that i created (I will paste the code below for reference) and checked dmesg logs for expected output: "Hangcheck: hangcheck value past margin!".
- Used Static Analysis tools
- Ensured module builds and inserts cleanly after changes.

Let me know if you want me to do more testing on this module.

[] hangtest.c (testing module i created to test hangcheck-timer module):

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Clint George");
MODULE_DESCRIPTION("Hang test for testing hangcheck-timer");

static int hang_duration = 20;
module_param(hang_duration, int, 0644);

static int __init hangtest_init(void) {
    unsigned long timeout;

    printk(KERN_INFO "hangtest: Disabling interrupts for %d seconds...\n", hang_duration);

    local_irq_disable();
    preempt_disable();

    timeout = jiffies + (hang_duration * HZ);
    while (time_before(jiffies, timeout)) {
        cpu_relax();
        barrier();
    }

    preempt_enable();
    local_irq_enable();

    printk(KERN_INFO "hangtest: Interrupts re-enabled\n");
//    return 0;
    return -EINVAL; // Return error so module doesn't stay loaded
}

static void __exit hangtest_exit(void) {
    printk(KERN_INFO "hangtest: Exit\n");
}

module_init(hangtest_init);
module_exit(hangtest_exit);

 drivers/char/hangcheck-timer.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/char/hangcheck-timer.c b/drivers/char/hangcheck-timer.c
index 497fc167c..a95e6d608 100644
--- a/drivers/char/hangcheck-timer.c
+++ b/drivers/char/hangcheck-timer.c
@@ -69,7 +69,8 @@ MODULE_VERSION(VERSION_STR);
 static int __init hangcheck_parse_tick(char *str)
 {
 	int par;
-	if (get_option(&str,&par))
+
+	if (get_option(&str, &par))
 		hangcheck_tick = par;
 	return 1;
 }
@@ -77,7 +78,8 @@ static int __init hangcheck_parse_tick(char *str)
 static int __init hangcheck_parse_margin(char *str)
 {
 	int par;
-	if (get_option(&str,&par))
+
+	if (get_option(&str, &par))
 		hangcheck_margin = par;
 	return 1;
 }
@@ -85,7 +87,8 @@ static int __init hangcheck_parse_margin(char *str)
 static int __init hangcheck_parse_reboot(char *str)
 {
 	int par;
-	if (get_option(&str,&par))
+
+	if (get_option(&str, &par))
 		hangcheck_reboot = par;
 	return 1;
 }
@@ -93,7 +96,8 @@ static int __init hangcheck_parse_reboot(char *str)
 static int __init hangcheck_parse_dump_tasks(char *str)
 {
 	int par;
-	if (get_option(&str,&par))
+
+	if (get_option(&str, &par))
 		hangcheck_dump_tasks = par;
 	return 1;
 }
@@ -126,23 +130,24 @@ static void hangcheck_fire(struct timer_list *unused)
 
 	if (tsc_diff > hangcheck_tsc_margin) {
 		if (hangcheck_dump_tasks) {
-			printk(KERN_CRIT "Hangcheck: Task state:\n");
+			pr_crit("Hangcheck: Task state:\n");
+
 #ifdef CONFIG_MAGIC_SYSRQ
 			handle_sysrq('t');
 #endif  /* CONFIG_MAGIC_SYSRQ */
 		}
 		if (hangcheck_reboot) {
-			printk(KERN_CRIT "Hangcheck: hangcheck is restarting the machine.\n");
+			pr_crit("Hangcheck: hangcheck is restarting the machine.\n");
 			emergency_restart();
 		} else {
-			printk(KERN_CRIT "Hangcheck: hangcheck value past margin!\n");
+			pr_crit("Hangcheck: hangcheck value past margin!\n");
 		}
 	}
 #if 0
 	/*
 	 * Enable to investigate delays in detail
 	 */
-	printk("Hangcheck: called %Ld ns since last time (%Ld ns overshoot)\n",
+	pr_debug("Hangcheck: called %lld ns since last time (%lld ns overshoot)\n",
 			tsc_diff, tsc_diff - hangcheck_tick*TIMER_FREQ);
 #endif
 	mod_timer(&hangcheck_ticktock, jiffies + (hangcheck_tick*HZ));
@@ -152,7 +157,7 @@ static void hangcheck_fire(struct timer_list *unused)
 
 static int __init hangcheck_init(void)
 {
-	printk("Hangcheck: starting hangcheck timer %s (tick is %d seconds, margin is %d seconds).\n",
+	pr_debug("Hangcheck: starting hangcheck timer %s (tick is %d seconds, margin is %d seconds).\n",
 	       VERSION_STR, hangcheck_tick, hangcheck_margin);
 	hangcheck_tsc_margin =
 		(unsigned long long)hangcheck_margin + hangcheck_tick;
@@ -168,7 +173,7 @@ static int __init hangcheck_init(void)
 static void __exit hangcheck_exit(void)
 {
 	timer_delete_sync(&hangcheck_ticktock);
-        printk("Hangcheck: Stopped hangcheck timer.\n");
+	pr_debug("Hangcheck: Stopped hangcheck timer.\n");
 }
 
 module_init(hangcheck_init);
-- 
2.34.1