fix idle (arch, acpi and apm) and lockdep

[mirror_ubuntu-artful-kernel.git] / arch / x86 / kernel / process.c

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 3004d716539dde2b882acd4e0576676531382965..67e9b4a1e89d5a1ac3a3851beaab9d48bbe22c0b 100644 (file)
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -4,6 +4,8 @@
 #include <linux/smp.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
+#include <linux/module.h>
+#include <linux/pm.h>
 
 struct kmem_cache *task_xstate_cachep;
 
@@ -42,3 +44,118 @@ void arch_task_cache_init(void)
                                  __alignof__(union thread_xstate),
                                  SLAB_PANIC, NULL);
 }
+
+static void do_nothing(void *unused)
+{
+}
+
+/*
+ * cpu_idle_wait - Used to ensure that all the CPUs discard old value of
+ * pm_idle and update to new pm_idle value. Required while changing pm_idle
+ * handler on SMP systems.
+ *
+ * Caller must have changed pm_idle to the new value before the call. Old
+ * pm_idle value will not be used by any CPU after the return of this function.
+ */
+void cpu_idle_wait(void)
+{
+       smp_mb();
+       /* kick all the CPUs so that they exit out of pm_idle */
+       smp_call_function(do_nothing, NULL, 0, 1);
+}
+EXPORT_SYMBOL_GPL(cpu_idle_wait);
+
+/*
+ * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
+ * which can obviate IPI to trigger checking of need_resched.
+ * We execute MONITOR against need_resched and enter optimized wait state
+ * through MWAIT. Whenever someone changes need_resched, we would be woken
+ * up from MWAIT (without an IPI).
+ *
+ * New with Core Duo processors, MWAIT can take some hints based on CPU
+ * capability.
+ */
+void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
+{
+       if (!need_resched()) {
+               __monitor((void *)&current_thread_info()->flags, 0, 0);
+               smp_mb();
+               if (!need_resched())
+                       __mwait(ax, cx);
+       }
+}
+
+/* Default MONITOR/MWAIT with no hints, used for default C1 state */
+static void mwait_idle(void)
+{
+       if (!need_resched()) {
+               __monitor((void *)&current_thread_info()->flags, 0, 0);
+               smp_mb();
+               if (!need_resched())
+                       __sti_mwait(0, 0);
+               else
+                       local_irq_enable();
+       } else
+               local_irq_enable();
+}
+
+
+static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c)
+{
+       if (force_mwait)
+               return 1;
+       /* Any C1 states supported? */
+       return c->cpuid_level >= 5 && ((cpuid_edx(5) >> 4) & 0xf) > 0;
+}
+
+/*
+ * On SMP it's slightly faster (but much more power-consuming!)
+ * to poll the ->work.need_resched flag instead of waiting for the
+ * cross-CPU IPI to arrive. Use this option with caution.
+ */
+static void poll_idle(void)
+{
+       local_irq_enable();
+       cpu_relax();
+}
+
+void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
+{
+       static int selected;
+
+       if (selected)
+               return;
+#ifdef CONFIG_X86_SMP
+       if (pm_idle == poll_idle && smp_num_siblings > 1) {
+               printk(KERN_WARNING "WARNING: polling idle and HT enabled,"
+                       " performance may degrade.\n");
+       }
+#endif
+       if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
+               /*
+                * Skip, if setup has overridden idle.
+                * One CPU supports mwait => All CPUs supports mwait
+                */
+               if (!pm_idle) {
+                       printk(KERN_INFO "using mwait in idle threads.\n");
+                       pm_idle = mwait_idle;
+               }
+       }
+       selected = 1;
+}
+
+static int __init idle_setup(char *str)
+{
+       if (!strcmp(str, "poll")) {
+               printk("using polling idle threads.\n");
+               pm_idle = poll_idle;
+       } else if (!strcmp(str, "mwait"))
+               force_mwait = 1;
+       else
+               return -1;
+
+       boot_option_idle_override = 1;
+       return 0;
+}
+early_param("idle", idle_setup);
+