[PATCH] sched: resched and cpu_idle rework

[mirror_ubuntu-bionic-kernel.git] / arch / i386 / kernel / process.c

diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index 5296e284ea363b631f1663204acfd581db5dd01d..1cb261f225d580939785c0b9fc94859dcf92a8a0 100644 (file)
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -99,14 +99,22 @@ EXPORT_SYMBOL(enable_hlt);
  */
 void default_idle(void)
 {
+       local_irq_enable();
+
        if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
-               local_irq_disable();
-               if (!need_resched())
-                       safe_halt();
-               else
-                       local_irq_enable();
+               clear_thread_flag(TIF_POLLING_NRFLAG);
+               smp_mb__after_clear_bit();
+               while (!need_resched()) {
+                       local_irq_disable();
+                       if (!need_resched())
+                               safe_halt();
+                       else
+                               local_irq_enable();
+               }
+               set_thread_flag(TIF_POLLING_NRFLAG);
        } else {
-               cpu_relax();
+               while (!need_resched())
+                       cpu_relax();
        }
 }
 #ifdef CONFIG_APM_MODULE
@@ -120,29 +128,14 @@ EXPORT_SYMBOL(default_idle);
  */
 static void poll_idle (void)
 {
-       int oldval;
-
        local_irq_enable();
 
-       /*
-        * Deal with another CPU just having chosen a thread to
-        * run here:
-        */
-       oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
-
-       if (!oldval) {
-               set_thread_flag(TIF_POLLING_NRFLAG);
-               asm volatile(
-                       "2:"
-                       "testl %0, %1;"
-                       "rep; nop;"
-                       "je 2b;"
-                       : : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags));
-
-               clear_thread_flag(TIF_POLLING_NRFLAG);
-       } else {
-               set_need_resched();
-       }
+       asm volatile(
+               "2:"
+               "testl %0, %1;"
+               "rep; nop;"
+               "je 2b;"
+               : : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags));
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
@@ -181,6 +174,8 @@ void cpu_idle(void)
 {
        int cpu = smp_processor_id();
 
+       set_thread_flag(TIF_POLLING_NRFLAG);
+
        /* endless idle loop with no priority at all */
        while (1) {
                while (!need_resched()) {
@@ -246,15 +241,12 @@ static void mwait_idle(void)
 {
        local_irq_enable();
 
-       if (!need_resched()) {
-               set_thread_flag(TIF_POLLING_NRFLAG);
-               do {
-                       __monitor((void *)&current_thread_info()->flags, 0, 0);
-                       if (need_resched())
-                               break;
-                       __mwait(0, 0);
-               } while (!need_resched());
-               clear_thread_flag(TIF_POLLING_NRFLAG);
+       while (!need_resched()) {
+               __monitor((void *)&current_thread_info()->flags, 0, 0);
+               smp_mb();
+               if (need_resched())
+                       break;
+               __mwait(0, 0);
        }
 }