Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Anna-Maria Behnsen <anna-maria@linutronix.de>
To:     linux-kernel@vger.kernel.org
Cc:     Peter Zijlstra <peterz@infradead.org>,
        John Stultz <jstultz@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Eric Dumazet <edumazet@google.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
        Arjan van de Ven <arjan@infradead.org>,
        "Paul E . McKenney" <paulmck@kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Rik van Riel <riel@surriel.com>,
        Anna-Maria Behnsen <anna-maria@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>, "Theodore Ts'o" <tytso@mit.edu>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>,
        Stephen Boyd <sboyd@kernel.org>, Tejun Heo <tj@kernel.org>,
        Lai Jiangshan <jiangshanlai@gmail.com>
Subject: [PATCH v4 05/16] add_timer_on(): Make sure callers have TIMER_PINNED flag
Date:   Fri,  4 Nov 2022 15:57:26 +0100
Message-Id: <20221104145737.71236-6-anna-maria@linutronix.de>
In-Reply-To: <20221104145737.71236-1-anna-maria@linutronix.de>
References: <20221104145737.71236-1-anna-maria@linutronix.de>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The implementation of the hierachical timer pull model will change the
timer bases per CPU. Timers, that have to expire on a specific CPU, require
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. Timers with TIMER_DEFERRABLE flag end up in a separate base anyway
and are executed on the local CPU only.

Therefore add the missing TIMER_PINNED flag for those callers who use
add_timer_on() without the flag. No functional change.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: John Stultz <jstultz@google.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
---
v4:
  - Move patch before local and global base are introduced
  - Add missing user (drivers/char/random.c) of add_timer_on() without
    TIMER_PINNED flag (kernel test robot)
---
 arch/x86/kernel/tsc_sync.c | 3 ++-
 drivers/char/random.c      | 2 +-
 kernel/time/clocksource.c  | 2 +-
 kernel/workqueue.c         | 7 +++++--
 4 files changed, 9 insertions(+), 5 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/drivers/char/random.c b/drivers/char/random.c
index 69754155300e..2cae98dc86dc 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -949,7 +949,7 @@ static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = {
 #define FASTMIX_PERM HSIPHASH_PERMUTATION
 	.pool = { HSIPHASH_CONST_0, HSIPHASH_CONST_1, HSIPHASH_CONST_2, HSIPHASH_CONST_3 },
 #endif
-	.mix = __TIMER_INITIALIZER(mix_interrupt_randomness, 0)
+	.mix = __TIMER_INITIALIZER(mix_interrupt_randomness, TIMER_PINNED)
 };
 
 /*
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