linux-kernel - [PATCH 06/10] watchdog/buddy: Cleanup how watchdog_buddy_check

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Message-ID: <20230526184139.6.I006c7d958a1ea5c4e1e4dc44a25596d9bb5fd3ba@changeid>
Date:   Fri, 26 May 2023 18:41:36 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     Petr Mladek <pmladek@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     kgdb-bugreport@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        Nicholas Piggin <npiggin@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev@...ts.ozlabs.org,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        sparclinux@...r.kernel.org,
        "David S . Miller" <davem@...emloft.net>,
        linux-perf-users@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>
Subject: [PATCH 06/10] watchdog/buddy: Cleanup how watchdog_buddy_check_hardlockup() is called

In the patch ("watchdog/hardlockup: detect hard lockups using
secondary (buddy) CPUs"), we added a call from the common watchdog.c
file into the buddy. That call could be done more cleanly.
Specifically:
1. If we move the call into watchdog_hardlockup_kick() then it keeps
   watchdog_timer_fn() simpler.
2. We don't need to pass an "unsigned long" to the buddy for the timer
   count. In the patch ("watchdog/hardlockup: add a "cpu" param to
   watchdog_hardlockup_check()") the count was changed to "atomic_t"
   which is backed by an int, so we should match types.

Suggested-by: Petr Mladek <pmladek@...e.com>
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

 include/linux/nmi.h     |  4 ++--
 kernel/watchdog.c       | 15 +++++++--------
 kernel/watchdog_buddy.c |  2 +-
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 6c6a5ce77c66..43893e5f858a 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -114,9 +114,9 @@ void watchdog_hardlockup_disable(unsigned int cpu);
 void lockup_detector_reconfigure(void);
 
 #ifdef CONFIG_HARDLOCKUP_DETECTOR_BUDDY
-void watchdog_buddy_check_hardlockup(unsigned long hrtimer_interrupts);
+void watchdog_buddy_check_hardlockup(int hrtimer_interrupts);
 #else
-static inline void watchdog_buddy_check_hardlockup(unsigned long hrtimer_interrupts) {}
+static inline void watchdog_buddy_check_hardlockup(int hrtimer_interrupts) {}
 #endif
 
 /**
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 85f4839b6faf..6cc46b8e3d07 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -131,9 +131,12 @@ static bool is_hardlockup(unsigned int cpu)
 	return false;
 }
 
-static unsigned long watchdog_hardlockup_kick(void)
+static void watchdog_hardlockup_kick(void)
 {
-	return atomic_inc_return(this_cpu_ptr(&hrtimer_interrupts));
+	int new_interrupts;
+
+	new_interrupts = atomic_inc_return(this_cpu_ptr(&hrtimer_interrupts));
+	watchdog_buddy_check_hardlockup(new_interrupts);
 }
 
 void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs)
@@ -195,7 +198,7 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs)
 
 #else /* CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER */
 
-static inline unsigned long watchdog_hardlockup_kick(void) { return 0; }
+static inline void watchdog_hardlockup_kick(void) { }
 
 #endif /* !CONFIG_HARDLOCKUP_DETECTOR_COUNTS_HRTIMER */
 
@@ -449,15 +452,11 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
 	struct pt_regs *regs = get_irq_regs();
 	int duration;
 	int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;
-	unsigned long hrtimer_interrupts;
 
 	if (!watchdog_enabled)
 		return HRTIMER_NORESTART;
 
-	hrtimer_interrupts = watchdog_hardlockup_kick();
-
-	/* test for hardlockups */
-	watchdog_buddy_check_hardlockup(hrtimer_interrupts);
+	watchdog_hardlockup_kick();
 
 	/* kick the softlockup detector */
 	if (completion_done(this_cpu_ptr(&softlockup_completion))) {
diff --git a/kernel/watchdog_buddy.c b/kernel/watchdog_buddy.c
index fee45af2e5bd..3ffc5f2ede5a 100644
--- a/kernel/watchdog_buddy.c
+++ b/kernel/watchdog_buddy.c
@@ -72,7 +72,7 @@ void watchdog_hardlockup_disable(unsigned int cpu)
 	cpumask_clear_cpu(cpu, &watchdog_cpus);
 }
 
-void watchdog_buddy_check_hardlockup(unsigned long hrtimer_interrupts)
+void watchdog_buddy_check_hardlockup(int hrtimer_interrupts)
 {
 	unsigned int next_cpu;
 
-- 
2.41.0.rc0.172.g3f132b7071-goog