btrfs: flush write bio if we loop in extent_write_cache_pages

[sagit-ice-cold/kernel_xiaomi_msm8998.git] / kernel / cpu.c

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 85ff5e2..985195b 100644 (file)
--- 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>
@@ -183,15 +184,28 @@ void cpu_hotplug_disable(void)
 }
 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)
 {
@@ -223,12 +237,6 @@ static int cpu_notify(unsigned long val, void *v)
        return __cpu_notify(val, v, -1, NULL);
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
-
-static void cpu_notify_nofail(unsigned long val, void *v)
-{
-       BUG_ON(cpu_notify(val, v));
-}
 EXPORT_SYMBOL(register_cpu_notifier);
 EXPORT_SYMBOL(__register_cpu_notifier);
 
@@ -246,6 +254,12 @@ void __unregister_cpu_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL(__unregister_cpu_notifier);
 
+#ifdef CONFIG_HOTPLUG_CPU
+static void cpu_notify_nofail(unsigned long val, void *v)
+{
+       BUG_ON(cpu_notify(val, v));
+}
+
 /**
  * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
  * @cpu: a CPU id
@@ -427,6 +441,7 @@ out_release:
        cpu_hotplug_done();
        if (!err)
                cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
+       arch_smt_update();
        return err;
 }
 
@@ -530,7 +545,7 @@ out_notify:
                __cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
 out:
        cpu_hotplug_done();
-
+       arch_smt_update();
        return ret;
 }
 
@@ -626,7 +641,7 @@ void enable_nonboot_cpus(void)
 
        /* 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;
 
@@ -827,3 +842,19 @@ void init_cpu_online(const struct cpumask *src)
 {
        cpumask_copy(to_cpumask(cpu_online_bits), src);
 }
+
+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;
+       else
+               pr_crit("Unsupported mitigations=%s, system may still be vulnerable\n",
+                       arg);
+
+       return 0;
+}
+early_param("mitigations", mitigations_parse_cmdline);