linux-kernel - [PATCH v3 16/17] add_timer_on(): Make sure callers have TIMER

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Date:   Tue, 25 Oct 2022 15:58:49 +0200
From:   Anna-Maria Behnsen <anna-maria@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        John Stultz <john.stultz@...aro.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        linux-pm@...r.kernel.org, Arjan van de Ven <arjan@...radead.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Rik van Riel <riel@...hat.com>,
        Anna-Maria Behnsen <anna-maria@...utronix.de>
Subject: [PATCH v3 16/17] add_timer_on(): Make sure callers have TIMER_PINNED flag

The hierachical timer pull model at expiry time is now in place. Timers
which should expire on a dedicated CPU needs the TIMER_PINNED
flag. Otherwise they will be queued on the dedicated CPU but in global
timer base and those timers could also expire on other CPUs. Only timers
with TIMER_PINNED flag will end up in local timer base

Therefore add the missing TIMER_PINNED flag for those who use
add_timer_on() without the flag.

Signed-off-by: Anna-Maria Behnsen <anna-maria@...utronix.de>
---
 arch/x86/kernel/tsc_sync.c | 3 ++-
 kernel/time/clocksource.c  | 2 +-
 kernel/workqueue.c         | 7 +++++--
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index 9452dc9664b5..eab827288e0f 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -110,7 +110,8 @@ static int __init start_sync_check_timer(void)
 	if (!cpu_feature_enabled(X86_FEATURE_TSC_ADJUST) || tsc_clocksource_reliable)
 		return 0;
 
-	timer_setup(&tsc_sync_check_timer, tsc_sync_check_timer_fn, 0);
+	timer_setup(&tsc_sync_check_timer, tsc_sync_check_timer_fn,
+		    TIMER_PINNED);
 	tsc_sync_check_timer.expires = jiffies + SYNC_CHECK_INTERVAL;
 	add_timer(&tsc_sync_check_timer);
 
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 8058bec87ace..f8c310e62758 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -523,7 +523,7 @@ static inline void clocksource_start_watchdog(void)
 {
 	if (watchdog_running || !watchdog || list_empty(&watchdog_list))
 		return;
-	timer_setup(&watchdog_timer, clocksource_watchdog, 0);
+	timer_setup(&watchdog_timer, clocksource_watchdog, TIMER_PINNED);
 	watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL;
 	add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask));
 	watchdog_running = 1;
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 7cd5f5e7e0a1..a0f7bf7be6f2 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1670,10 +1670,13 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
 	dwork->cpu = cpu;
 	timer->expires = jiffies + delay;
 
-	if (unlikely(cpu != WORK_CPU_UNBOUND))
+	if (unlikely(cpu != WORK_CPU_UNBOUND)) {
+		timer->flags |= TIMER_PINNED;
 		add_timer_on(timer, cpu);
-	else
+	} else {
+		timer->flags &= ~TIMER_PINNED;
 		add_timer(timer);
+	}
 }
 
 /**
-- 
2.30.2