commit de4569d13552c16785af0458e7e50cbc9338008a
author Clarence.Zhou <clarencez@nvidia.com> Wed Sep 25 17:40:28 2019 +0800
committer Clarence Zhou <clarencez@nvidia.com> Tue Oct 15 20:06:18 2019 -0700
tree a46ac5e40491170b38b7766e77af238c91222e78
parent d78d1673585f6fe3ddabe2dcf567965fdf92b40b
parent 0f654c12cd720e65f1fb3174a7ee468f1daa09e7

Merge remote-tracking branch 'origin/dev/linux-4.4.180' into rel-28

Conflicts:
	arch/arm64/kernel/traps.c
	drivers/dma/tegra20-apb-dma.c
	drivers/gpu/drm/vmwgfx/vmwgfx_fb.c
	drivers/hwtracing/coresight/coresight-etm4x.c
	drivers/i2c/busses/i2c-tegra.c
	drivers/usb/gadget/configfs.c
	include/linux/cpu.h
	kernel/cpu.c
	kernel/sched/fair.c
	sound/core/compress_offload.c

Bug 200554552

Change-Id: I6fd681159f3dd91bf1a4e44e8aedf0d556a4a903

kernel/cpu.c

diff --git a/kernel/cpu.c b/kernel/cpu.c
index bdf20aa..45a349c 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -8,6 +8,7 @@
 #include <linux/init.h>
 #include <linux/notifier.h>
 #include <linux/sched.h>
+#include <linux/sched/smt.h>
 #include <linux/unistd.h>
 #include <linux/cpu.h>
 #include <linux/oom.h>
@@ -185,15 +186,28 @@
 }
 EXPORT_SYMBOL_GPL(cpu_hotplug_disable);
 
+static void __cpu_hotplug_enable(void)
+{
+	if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
+		return;
+	cpu_hotplug_disabled--;
+}
+
 void cpu_hotplug_enable(void)
 {
 	cpu_maps_update_begin();
-	WARN_ON(--cpu_hotplug_disabled < 0);
+	__cpu_hotplug_enable();
 	cpu_maps_update_done();
 }
 EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
 #endif	/* CONFIG_HOTPLUG_CPU */
 
+/*
+ * Architectures that need SMT-specific errata handling during SMT hotplug
+ * should override this.
+ */
+void __weak arch_smt_update(void) { }
+
 /* Need to know about CPUs going up/down? */
 int register_cpu_notifier(struct notifier_block *nb)
 {
@@ -428,9 +442,9 @@
 
 out_release:
 	cpu_hotplug_done();
-	trace_sched_cpu_hotplug(cpu, err, 0);
 	if (!err)
 		cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
+	arch_smt_update();
 	return err;
 }
 
@@ -537,8 +551,7 @@
 		__cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
 out:
 	cpu_hotplug_done();
-	trace_sched_cpu_hotplug(cpu, ret, 1);
-
+	arch_smt_update();
 	return ret;
 }
 
@@ -637,7 +650,7 @@
 
 	/* Allow everyone to use the CPU hotplug again */
 	cpu_maps_update_begin();
-	WARN_ON(--cpu_hotplug_disabled < 0);
+	__cpu_hotplug_enable();
 	if (cpumask_empty(frozen_cpus))
 		goto out;
 
@@ -843,18 +856,31 @@
 
 void idle_notifier_register(struct notifier_block *n)
 {
-	atomic_notifier_chain_register(&idle_notifier, n);
+		atomic_notifier_chain_register(&idle_notifier, n);
 }
 EXPORT_SYMBOL_GPL(idle_notifier_register);
 
 void idle_notifier_unregister(struct notifier_block *n)
 {
-	atomic_notifier_chain_unregister(&idle_notifier, n);
+		atomic_notifier_chain_unregister(&idle_notifier, n);
 }
 EXPORT_SYMBOL_GPL(idle_notifier_unregister);
 
 void idle_notifier_call_chain(unsigned long val)
 {
-	atomic_notifier_call_chain(&idle_notifier, val, NULL);
+		atomic_notifier_call_chain(&idle_notifier, val, NULL);
 }
 EXPORT_SYMBOL_GPL(idle_notifier_call_chain);
+
+enum cpu_mitigations cpu_mitigations = CPU_MITIGATIONS_AUTO;
+
+static int __init mitigations_parse_cmdline(char *arg)
+{
+	if (!strcmp(arg, "off"))
+		cpu_mitigations = CPU_MITIGATIONS_OFF;
+	else if (!strcmp(arg, "auto"))
+		cpu_mitigations = CPU_MITIGATIONS_AUTO;
+
+	return 0;
+}
+early_param("mitigations", mitigations_parse_cmdline);