Merge remote-tracking branch 'drm/drm-next' into drm-misc-next

drm-next is forwarded to v4.20-rc1, and we need this to make
a patch series apply.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

1 files changed, 39 insertions, 1 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 0097acec1c71..3c7f3b4c453c 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -315,6 +315,16 @@ void lockdep_assert_cpus_held(void)
 	percpu_rwsem_assert_held(&cpu_hotplug_lock);
 }
 
+static void lockdep_acquire_cpus_lock(void)
+{
+	rwsem_acquire(&cpu_hotplug_lock.rw_sem.dep_map, 0, 0, _THIS_IP_);
+}
+
+static void lockdep_release_cpus_lock(void)
+{
+	rwsem_release(&cpu_hotplug_lock.rw_sem.dep_map, 1, _THIS_IP_);
+}
+
 /*
  * Wait for currently running CPU hotplug operations to complete (if any) and
  * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
@@ -344,6 +354,17 @@ void cpu_hotplug_enable(void)
 	cpu_maps_update_done();
 }
 EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
+
+#else
+
+static void lockdep_acquire_cpus_lock(void)
+{
+}
+
+static void lockdep_release_cpus_lock(void)
+{
+}
+
 #endif	/* CONFIG_HOTPLUG_CPU */
 
 #ifdef CONFIG_HOTPLUG_SMT
@@ -362,6 +383,7 @@ void __init cpu_smt_disable(bool force)
 		pr_info("SMT: Force disabled\n");
 		cpu_smt_control = CPU_SMT_FORCE_DISABLED;
 	} else {
+		pr_info("SMT: disabled\n");
 		cpu_smt_control = CPU_SMT_DISABLED;
 	}
 }
@@ -616,6 +638,12 @@ static void cpuhp_thread_fun(unsigned int cpu)
 	 */
 	smp_mb();
 
+	/*
+	 * The BP holds the hotplug lock, but we're now running on the AP,
+	 * ensure that anybody asserting the lock is held, will actually find
+	 * it so.
+	 */
+	lockdep_acquire_cpus_lock();
 	cpuhp_lock_acquire(bringup);
 
 	if (st->single) {
@@ -661,6 +689,7 @@ static void cpuhp_thread_fun(unsigned int cpu)
 	}
 
 	cpuhp_lock_release(bringup);
+	lockdep_release_cpus_lock();
 
 	if (!st->should_run)
 		complete_ap_thread(st, bringup);
@@ -2026,6 +2055,12 @@ static void cpuhp_online_cpu_device(unsigned int cpu)
 	kobject_uevent(&dev->kobj, KOBJ_ONLINE);
 }
 
+/*
+ * Architectures that need SMT-specific errata handling during SMT hotplug
+ * should override this.
+ */
+void __weak arch_smt_update(void) { };
+
 static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
 {
 	int cpu, ret = 0;
@@ -2052,8 +2087,10 @@ static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
 		 */
 		cpuhp_offline_cpu_device(cpu);
 	}
-	if (!ret)
+	if (!ret) {
 		cpu_smt_control = ctrlval;
+		arch_smt_update();
+	}
 	cpu_maps_update_done();
 	return ret;
 }
@@ -2064,6 +2101,7 @@ static int cpuhp_smt_enable(void)
 
 	cpu_maps_update_begin();
 	cpu_smt_control = CPU_SMT_ENABLED;
+	arch_smt_update();
 	for_each_present_cpu(cpu) {
 		/* Skip online CPUs and CPUs on offline nodes */
 		if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))