2 files changed, 130 insertions, 6 deletions

diff --git a/arch/i386/kernel/cpu/mcheck/p4.c b/arch/i386/kernel/cpu/mcheck/p4.c
index d83a669d376f..504434a46011 100644
--- a/arch/i386/kernel/cpu/mcheck/p4.c
+++ b/arch/i386/kernel/cpu/mcheck/p4.c
@@ -115,6 +115,9 @@ static void intel_init_thermal(struct cpuinfo_x86 *c)
         l = apic_read (APIC_LVTTHMR);
         apic_write_around (APIC_LVTTHMR, l & ~APIC_LVT_MASKED);
         printk (KERN_INFO "CPU%d: Thermal monitoring enabled\n", cpu);
+
+        /* enable thermal throttle processing */
+        atomic_set(&therm_throt_en, 1);
         return;
 }
 #endif /* CONFIG_X86_MCE_P4THERMAL */
diff --git a/arch/i386/kernel/cpu/mcheck/therm_throt.c b/arch/i386/kernel/cpu/mcheck/therm_throt.c
index 101f7ace00ce..4f43047de406 100644
--- a/arch/i386/kernel/cpu/mcheck/therm_throt.c
+++ b/arch/i386/kernel/cpu/mcheck/therm_throt.c
@@ -1,15 +1,22 @@
 /*
  * linux/arch/i386/kerne/cpu/mcheck/therm_throt.c
  *
- * Thermal throttle event support code.
+ * Thermal throttle event support code (such as syslog messaging and rate
+ * limiting) that was factored out from x86_64 (mce_intel.c) and i386 (p4.c).
+ * This allows consistent reporting of CPU thermal throttle events.
+ *
+ * Maintains a counter in /sys that keeps track of the number of thermal
+ * events, such that the user knows how bad the thermal problem might be
+ * (since the logging to syslog and mcelog is rate limited).
  *
  * Author: Dmitriy Zavin (dmitriyz@google.com)
  *
  * Credits: Adapted from Zwane Mwaikambo's original code in mce_intel.c.
- *
+ *          Inspired by Ross Biro's and Al Borchers' counter code.
  */
 
 #include <linux/percpu.h>
+#include <linux/sysdev.h>
 #include <linux/cpu.h>
 #include <asm/cpu.h>
 #include <linux/notifier.h>
@@ -18,15 +25,53 @@
 /* How long to wait between reporting thermal events */
 #define CHECK_INTERVAL              (300 * HZ)
 
-static DEFINE_PER_CPU(__u64, next_check);
+static DEFINE_PER_CPU(__u64, next_check) = INITIAL_JIFFIES;
+static DEFINE_PER_CPU(unsigned long, thermal_throttle_count);
+atomic_t therm_throt_en = ATOMIC_INIT(0);
+
+#ifdef CONFIG_SYSFS
+#define define_therm_throt_sysdev_one_ro(_name)                              \
+        static SYSDEV_ATTR(_name, 0444, therm_throt_sysdev_show_##_name, NULL)
+
+#define define_therm_throt_sysdev_show_func(name)                            \
+static ssize_t therm_throt_sysdev_show_##name(struct sys_device *dev,        \
+                                              char *buf)                     \
+{                                                                            \
+        unsigned int cpu = dev->id;                                          \
+        ssize_t ret;                                                         \
+                                                                             \
+        preempt_disable();              /* CPU hotplug */                    \
+        if (cpu_online(cpu))                                                 \
+                ret = sprintf(buf, "%lu\n",                                  \
+                              per_cpu(thermal_throttle_##name, cpu));        \
+        else                                                                 \
+                ret = 0;                                                     \
+        preempt_enable();                                                    \
+                                                                             \
+        return ret;                                                          \
+}
+
+define_therm_throt_sysdev_show_func(count);
+define_therm_throt_sysdev_one_ro(count);
+
+static struct attribute *thermal_throttle_attrs[] = {
+        &attr_count.attr,
+        NULL
+};
+
+static struct attribute_group thermal_throttle_attr_group = {
+        .attrs = thermal_throttle_attrs,
+        .name = "thermal_throttle"
+};
+#endif /* CONFIG_SYSFS */
 
 /***
- * therm_throt_process - Process thermal throttling event
+ * therm_throt_process - Process thermal throttling event from interrupt
  * @curr: Whether the condition is current or not (boolean), since the
  *        thermal interrupt normally gets called both when the thermal
  *        event begins and once the event has ended.
  *
- * This function is normally called by the thermal interrupt after the
+ * This function is called by the thermal interrupt after the
  * IRQ has been acknowledged.
  *
  * It will take care of rate limiting and printing messages to the syslog.
@@ -41,6 +86,9 @@ int therm_throt_process(int curr)
         unsigned int cpu = smp_processor_id();
         __u64 tmp_jiffs = get_jiffies_64();
 
+        if (curr)
+                __get_cpu_var(thermal_throttle_count)++;
+
         if (time_before64(tmp_jiffs, __get_cpu_var(next_check)))
                 return 0;
 
@@ -49,7 +97,9 @@ int therm_throt_process(int curr)
         /* if we just entered the thermal event */
         if (curr) {
                 printk(KERN_CRIT "CPU%d: Temperature above threshold, "
-                       "cpu clock throttled\n", cpu);
+                       "cpu clock throttled (total events = %lu)\n", cpu,
+                       __get_cpu_var(thermal_throttle_count));
+
                 add_taint(TAINT_MACHINE_CHECK);
         } else {
                 printk(KERN_CRIT "CPU%d: Temperature/speed normal\n", cpu);
@@ -57,3 +107,74 @@ int therm_throt_process(int curr)
 
         return 1;
 }
+
+#ifdef CONFIG_SYSFS
+/* Add/Remove thermal_throttle interface for CPU device */
+static __cpuinit int thermal_throttle_add_dev(struct sys_device * sys_dev)
+{
+        sysfs_create_group(&sys_dev->kobj, &thermal_throttle_attr_group);
+        return 0;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static __cpuinit int thermal_throttle_remove_dev(struct sys_device * sys_dev)
+{
+        sysfs_remove_group(&sys_dev->kobj, &thermal_throttle_attr_group);
+        return 0;
+}
+
+/* Mutex protecting device creation against CPU hotplug */
+static DEFINE_MUTEX(therm_cpu_lock);
+
+/* Get notified when a cpu comes on/off. Be hotplug friendly. */
+static __cpuinit int thermal_throttle_cpu_callback(struct notifier_block *nfb,
+                                                   unsigned long action,
+                                                   void *hcpu)
+{
+        unsigned int cpu = (unsigned long)hcpu;
+        struct sys_device *sys_dev;
+
+        sys_dev = get_cpu_sysdev(cpu);
+        mutex_lock(&therm_cpu_lock);
+        switch (action) {
+        case CPU_ONLINE:
+                thermal_throttle_add_dev(sys_dev);
+                break;
+        case CPU_DEAD:
+                thermal_throttle_remove_dev(sys_dev);
+                break;
+        }
+        mutex_unlock(&therm_cpu_lock);
+        return NOTIFY_OK;
+}
+
+static struct notifier_block thermal_throttle_cpu_notifier =
+{
+        .notifier_call = thermal_throttle_cpu_callback,
+};
+#endif /* CONFIG_HOTPLUG_CPU */
+
+static __init int thermal_throttle_init_device(void)
+{
+        unsigned int cpu = 0;
+
+        if (!atomic_read(&therm_throt_en))
+                return 0;
+
+        register_hotcpu_notifier(&thermal_throttle_cpu_notifier);
+
+#ifdef CONFIG_HOTPLUG_CPU
+        mutex_lock(&therm_cpu_lock);
+#endif
+        /* connect live CPUs to sysfs */
+        for_each_online_cpu(cpu)
+                thermal_throttle_add_dev(get_cpu_sysdev(cpu));
+#ifdef CONFIG_HOTPLUG_CPU
+        mutex_unlock(&therm_cpu_lock);
+#endif
+
+        return 0;
+}
+
+device_initcall(thermal_throttle_init_device);
+#endif /* CONFIG_SYSFS */