[S390] Processor degradation notification.

Generate uevents for all cpus if cpu capability changes. This can
happen e.g. because the cpus are overheating. The cpu capability can
be read via /sys/devices/system/cpu/cpuN/capability.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

1 files changed, 43 insertions, 5 deletions

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 7c0143fdf710..2c5de92958dd 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -821,19 +821,57 @@ int setup_profiling_timer(unsigned int multiplier)
 
 static DEFINE_PER_CPU(struct cpu, cpu_devices);
 
+static ssize_t show_capability(struct sys_device *dev, char *buf)
+{
+        unsigned int capability;
+        int rc;
+
+        rc = get_cpu_capability(&capability);
+        if (rc)
+                return rc;
+        return sprintf(buf, "%u\n", capability);
+}
+static SYSDEV_ATTR(capability, 0444, show_capability, NULL);
+
+static int __cpuinit smp_cpu_notify(struct notifier_block *self,
+                                    unsigned long action, void *hcpu)
+{
+        unsigned int cpu = (unsigned int)(long)hcpu;
+        struct cpu *c = &per_cpu(cpu_devices, cpu);
+        struct sys_device *s = &c->sysdev;
+
+        switch (action) {
+        case CPU_ONLINE:
+                if (sysdev_create_file(s, &attr_capability))
+                        return NOTIFY_BAD;
+                break;
+        case CPU_DEAD:
+                sysdev_remove_file(s, &attr_capability);
+                break;
+        }
+        return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata smp_cpu_nb = {
+        .notifier_call  = smp_cpu_notify,
+};
+
 static int __init topology_init(void)
 {
         int cpu;
-        int ret;
+
+        register_cpu_notifier(&smp_cpu_nb);
 
         for_each_possible_cpu(cpu) {
                 struct cpu *c = &per_cpu(cpu_devices, cpu);
+                struct sys_device *s = &c->sysdev;
 
                 c->hotpluggable = 1;
-                ret = register_cpu(c, cpu);
-                if (ret)
-                        printk(KERN_WARNING "topology_init: register_cpu %d "
-                               "failed (%d)\n", cpu, ret);
+                register_cpu(c, cpu);
+                if (!cpu_online(cpu))
+                        continue;
+                s = &c->sysdev;
+                sysdev_create_file(s, &attr_capability);
         }
         return 0;
 }