[IA64] Simplify cpu_idle_wait

This is just Venki's patch[*] for x86 ported to ia64.

* http://marc.info/?l=linux-kernel&m=120249201318159&w=2

Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index be6c6f7be02714d8cda1b5a2d10e2d84e39ade61..49937a383b23cb0f2a650173b8ff3fe3c990691b 100644 (file)
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -52,7 +52,6 @@
 #include "sigframe.h"
 
 void (*ia64_mark_idle)(int);
-static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
 
 unsigned long boot_option_idle_override = 0;
 EXPORT_SYMBOL(boot_option_idle_override);
@@ -254,33 +253,23 @@ static inline void play_dead(void)
 }
 #endif /* CONFIG_HOTPLUG_CPU */
 
-void cpu_idle_wait(void)
+static void do_nothing(void *unused)
 {
-       unsigned int cpu, this_cpu = get_cpu();
-       cpumask_t map;
-       cpumask_t tmp = current->cpus_allowed;
-
-       set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
-       put_cpu();
-
-       cpus_clear(map);
-       for_each_online_cpu(cpu) {
-               per_cpu(cpu_idle_state, cpu) = 1;
-               cpu_set(cpu, map);
-       }
-
-       __get_cpu_var(cpu_idle_state) = 0;
+}
 
-       wmb();
-       do {
-               ssleep(1);
-               for_each_online_cpu(cpu) {
-                       if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu))
-                               cpu_clear(cpu, map);
-               }
-               cpus_and(map, map, cpu_online_map);
-       } while (!cpus_empty(map));
-       set_cpus_allowed(current, tmp);
+/*
+ * 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);
 
@@ -308,9 +297,6 @@ cpu_idle (void)
 #ifdef CONFIG_SMP
                        min_xtp();
 #endif
-                       if (__get_cpu_var(cpu_idle_state))
-                               __get_cpu_var(cpu_idle_state) = 0;
-
                        rmb();
                        if (mark_idle)
                                (*mark_idle)(1);