Merging upstream version 6.9.7.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 13 insertions, 61 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index bac70ea54e..563877d6c2 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -54,7 +54,6 @@
  * @rollback:	Perform a rollback
  * @single:	Single callback invocation
  * @bringup:	Single callback bringup or teardown selector
- * @cpu:	CPU number
  * @node:	Remote CPU node; for multi-instance, do a
  *		single entry callback for install/remove
  * @last:	For multi-instance rollback, remember how far we got
@@ -1209,52 +1208,6 @@ void __init cpuhp_threads_init(void)
 	kthread_unpark(this_cpu_read(cpuhp_state.thread));
 }
 
-/*
- *
- * Serialize hotplug trainwrecks outside of the cpu_hotplug_lock
- * protected region.
- *
- * The operation is still serialized against concurrent CPU hotplug via
- * cpu_add_remove_lock, i.e. CPU map protection.  But it is _not_
- * serialized against other hotplug related activity like adding or
- * removing of state callbacks and state instances, which invoke either the
- * startup or the teardown callback of the affected state.
- *
- * This is required for subsystems which are unfixable vs. CPU hotplug and
- * evade lock inversion problems by scheduling work which has to be
- * completed _before_ cpu_up()/_cpu_down() returns.
- *
- * Don't even think about adding anything to this for any new code or even
- * drivers. It's only purpose is to keep existing lock order trainwrecks
- * working.
- *
- * For cpu_down() there might be valid reasons to finish cleanups which are
- * not required to be done under cpu_hotplug_lock, but that's a different
- * story and would be not invoked via this.
- */
-static void cpu_up_down_serialize_trainwrecks(bool tasks_frozen)
-{
-	/*
-	 * cpusets delegate hotplug operations to a worker to "solve" the
-	 * lock order problems. Wait for the worker, but only if tasks are
-	 * _not_ frozen (suspend, hibernate) as that would wait forever.
-	 *
-	 * The wait is required because otherwise the hotplug operation
-	 * returns with inconsistent state, which could even be observed in
-	 * user space when a new CPU is brought up. The CPU plug uevent
-	 * would be delivered and user space reacting on it would fail to
-	 * move tasks to the newly plugged CPU up to the point where the
-	 * work has finished because up to that point the newly plugged CPU
-	 * is not assignable in cpusets/cgroups. On unplug that's not
-	 * necessarily a visible issue, but it is still inconsistent state,
-	 * which is the real problem which needs to be "fixed". This can't
-	 * prevent the transient state between scheduling the work and
-	 * returning from waiting for it.
-	 */
-	if (!tasks_frozen)
-		cpuset_wait_for_hotplug();
-}
-
 #ifdef CONFIG_HOTPLUG_CPU
 #ifndef arch_clear_mm_cpumask_cpu
 #define arch_clear_mm_cpumask_cpu(cpu, mm) cpumask_clear_cpu(cpu, mm_cpumask(mm))
@@ -1324,10 +1277,6 @@ static int take_cpu_down(void *_param)
 	 */
 	cpuhp_invoke_callback_range_nofail(false, cpu, st, target);
 
-	/* Give up timekeeping duties */
-	tick_handover_do_timer();
-	/* Remove CPU from timer broadcasting */
-	tick_offline_cpu(cpu);
 	/* Park the stopper thread */
 	stop_machine_park(cpu);
 	return 0;
@@ -1403,6 +1352,7 @@ void cpuhp_report_idle_dead(void)
 	struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
 
 	BUG_ON(st->state != CPUHP_AP_OFFLINE);
+	tick_assert_timekeeping_handover();
 	rcutree_report_cpu_dead();
 	st->state = CPUHP_AP_IDLE_DEAD;
 	/*
@@ -1498,7 +1448,6 @@ out:
 	 */
 	lockup_detector_cleanup();
 	arch_smt_update();
-	cpu_up_down_serialize_trainwrecks(tasks_frozen);
 	return ret;
 }
 
@@ -1732,7 +1681,6 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
 out:
 	cpus_write_unlock();
 	arch_smt_update();
-	cpu_up_down_serialize_trainwrecks(tasks_frozen);
 	return ret;
 }
 
@@ -1909,14 +1857,14 @@ static bool __init cpuhp_bringup_cpus_parallel(unsigned int ncpus)
 static inline bool cpuhp_bringup_cpus_parallel(unsigned int ncpus) { return false; }
 #endif /* CONFIG_HOTPLUG_PARALLEL */
 
-void __init bringup_nonboot_cpus(unsigned int setup_max_cpus)
+void __init bringup_nonboot_cpus(unsigned int max_cpus)
 {
 	/* Try parallel bringup optimization if enabled */
-	if (cpuhp_bringup_cpus_parallel(setup_max_cpus))
+	if (cpuhp_bringup_cpus_parallel(max_cpus))
 		return;
 
 	/* Full per CPU serialized bringup */
-	cpuhp_bringup_mask(cpu_present_mask, setup_max_cpus, CPUHP_ONLINE);
+	cpuhp_bringup_mask(cpu_present_mask, max_cpus, CPUHP_ONLINE);
 }
 
 #ifdef CONFIG_PM_SLEEP_SMP
@@ -2205,7 +2153,11 @@ static struct cpuhp_step cpuhp_hp_states[] = {
 		.startup.single		= NULL,
 		.teardown.single	= hrtimers_cpu_dying,
 	},
-
+	[CPUHP_AP_TICK_DYING] = {
+		.name			= "tick:dying",
+		.startup.single		= NULL,
+		.teardown.single	= tick_cpu_dying,
+	},
 	/* Entry state on starting. Interrupts enabled from here on. Transient
 	 * state for synchronsization */
 	[CPUHP_AP_ONLINE] = {
@@ -3005,7 +2957,7 @@ static ssize_t control_show(struct device *dev,
 		return sysfs_emit(buf, "%d\n", cpu_smt_num_threads);
 #endif
 
-	return snprintf(buf, PAGE_SIZE - 2, "%s\n", state);
+	return sysfs_emit(buf, "%s\n", state);
 }
 
 static ssize_t control_store(struct device *dev, struct device_attribute *attr,
@@ -3018,7 +2970,7 @@ static DEVICE_ATTR_RW(control);
 static ssize_t active_show(struct device *dev,
 			   struct device_attribute *attr, char *buf)
 {
-	return snprintf(buf, PAGE_SIZE - 2, "%d\n", sched_smt_active());
+	return sysfs_emit(buf, "%d\n", sched_smt_active());
 }
 static DEVICE_ATTR_RO(active);
 
@@ -3107,10 +3059,10 @@ const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
 EXPORT_SYMBOL(cpu_all_bits);
 
 #ifdef CONFIG_INIT_ALL_POSSIBLE
-struct cpumask __cpu_possible_mask __read_mostly
+struct cpumask __cpu_possible_mask __ro_after_init
 	= {CPU_BITS_ALL};
 #else
-struct cpumask __cpu_possible_mask __read_mostly;
+struct cpumask __cpu_possible_mask __ro_after_init;
 #endif
 EXPORT_SYMBOL(__cpu_possible_mask);