7 files changed, 85 insertions, 1 deletions

diff --git a/arch/i386/kernel/apic.c b/arch/i386/kernel/apic.c
index 629c5ed94260..f4159e0a7ae9 100644
--- a/arch/i386/kernel/apic.c
+++ b/arch/i386/kernel/apic.c
@@ -36,6 +36,7 @@
 #include <asm/hpet.h>
 #include <asm/i8253.h>
 #include <asm/nmi.h>
+#include <asm/idle.h>
 
 #include <mach_apic.h>
 #include <mach_apicdef.h>
@@ -1255,6 +1256,7 @@ fastcall void smp_apic_timer_interrupt(struct pt_regs *regs)
          * Besides, if we don't timer interrupts ignore the global
          * interrupt lock, which is the WrongThing (tm) to do.
          */
+        exit_idle();
         irq_enter();
         smp_local_timer_interrupt();
         irq_exit();
@@ -1305,6 +1307,7 @@ fastcall void smp_spurious_interrupt(struct pt_regs *regs)
 {
         unsigned long v;
 
+        exit_idle();
         irq_enter();
         /*
          * Check if this really is a spurious interrupt and ACK it
@@ -1329,6 +1332,7 @@ fastcall void smp_error_interrupt(struct pt_regs *regs)
 {
         unsigned long v, v1;
 
+        exit_idle();
         irq_enter();
         /* First tickle the hardware, only then report what went on. -- REW */
         v = apic_read(APIC_ESR);
diff --git a/arch/i386/kernel/cpu/mcheck/p4.c b/arch/i386/kernel/cpu/mcheck/p4.c
index 504434a46011..8359c19d3a23 100644
--- a/arch/i386/kernel/cpu/mcheck/p4.c
+++ b/arch/i386/kernel/cpu/mcheck/p4.c
@@ -12,6 +12,7 @@
 #include <asm/system.h>
 #include <asm/msr.h>
 #include <asm/apic.h>
+#include <asm/idle.h>
 
 #include <asm/therm_throt.h>
 
@@ -59,6 +60,7 @@ static void (*vendor_thermal_interrupt)(struct pt_regs *regs) = unexpected_therm
 
 fastcall void smp_thermal_interrupt(struct pt_regs *regs)
 {
+        exit_idle();
         irq_enter();
         vendor_thermal_interrupt(regs);
         irq_exit();
diff --git a/arch/i386/kernel/irq.c b/arch/i386/kernel/irq.c
index 3201d421090a..5785d84103a6 100644
--- a/arch/i386/kernel/irq.c
+++ b/arch/i386/kernel/irq.c
@@ -19,6 +19,8 @@
 #include <linux/cpu.h>
 #include <linux/delay.h>
 
+#include <asm/idle.h>
+
 DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_internodealigned_in_smp;
 EXPORT_PER_CPU_SYMBOL(irq_stat);
 
@@ -61,6 +63,7 @@ fastcall unsigned int do_IRQ(struct pt_regs *regs)
         union irq_ctx *curctx, *irqctx;
         u32 *isp;
 #endif
+        exit_idle();
 
         if (unlikely((unsigned)irq >= NR_IRQS)) {
                 printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index 05be77413351..7845d480c293 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -48,6 +48,7 @@
 #include <asm/i387.h>
 #include <asm/desc.h>
 #include <asm/vm86.h>
+#include <asm/idle.h>
 #ifdef CONFIG_MATH_EMULATION
 #include <asm/math_emu.h>
 #endif
@@ -80,6 +81,42 @@ void (*pm_idle)(void);
 EXPORT_SYMBOL(pm_idle);
 static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
 
+static ATOMIC_NOTIFIER_HEAD(idle_notifier);
+
+void idle_notifier_register(struct notifier_block *n)
+{
+        atomic_notifier_chain_register(&idle_notifier, n);
+}
+
+void idle_notifier_unregister(struct notifier_block *n)
+{
+        atomic_notifier_chain_unregister(&idle_notifier, n);
+}
+
+static DEFINE_PER_CPU(volatile unsigned long, idle_state);
+
+void enter_idle(void)
+{
+        /* needs to be atomic w.r.t. interrupts, not against other CPUs */
+        __set_bit(0, &__get_cpu_var(idle_state));
+        atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
+}
+
+static void __exit_idle(void)
+{
+        /* needs to be atomic w.r.t. interrupts, not against other CPUs */
+        if (__test_and_clear_bit(0, &__get_cpu_var(idle_state)) == 0)
+                return;
+        atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
+}
+
+void exit_idle(void)
+{
+        if (current->pid)
+                return;
+        __exit_idle();
+}
+
 void disable_hlt(void)
 {
         hlt_counter++;
@@ -130,6 +167,7 @@ EXPORT_SYMBOL(default_idle);
  */
 static void poll_idle (void)
 {
+        local_irq_enable();
         cpu_relax();
 }
 
@@ -189,7 +227,16 @@ void cpu_idle(void)
                                 play_dead();
 
                         __get_cpu_var(irq_stat).idle_timestamp = jiffies;
+
+                        /*
+                         * Idle routines should keep interrupts disabled
+                         * from here on, until they go to idle.
+                         * Otherwise, idle callbacks can misfire.
+                         */
+                        local_irq_disable();
+                        enter_idle();
                         idle();
+                        __exit_idle();
                 }
                 preempt_enable_no_resched();
                 schedule();
@@ -243,7 +290,11 @@ void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
                 __monitor((void *)&current_thread_info()->flags, 0, 0);
                 smp_mb();
                 if (!need_resched())
-                        __mwait(eax, ecx);
+                        __sti_mwait(eax, ecx);
+                else
+                        local_irq_enable();
+        } else {
+                local_irq_enable();
         }
 }
 
diff --git a/arch/i386/kernel/smp.c b/arch/i386/kernel/smp.c
index 5285aff8367f..ffc4f65c5189 100644
--- a/arch/i386/kernel/smp.c
+++ b/arch/i386/kernel/smp.c
@@ -23,6 +23,7 @@
 
 #include <asm/mtrr.h>
 #include <asm/tlbflush.h>
+#include <asm/idle.h>
 #include <mach_apic.h>
 
 /*
@@ -624,6 +625,7 @@ fastcall void smp_call_function_interrupt(struct pt_regs *regs)
         /*
          * At this point the info structure may be out of scope unless wait==1
          */
+        exit_idle();
         irq_enter();
         (*func)(info);
         irq_exit();
diff --git a/include/asm-i386/idle.h b/include/asm-i386/idle.h
new file mode 100644
index 000000000000..87ab93911199
--- /dev/null
+++ b/include/asm-i386/idle.h
@@ -0,0 +1,14 @@
+#ifndef _ASM_I386_IDLE_H
+#define _ASM_I386_IDLE_H 1
+
+#define IDLE_START 1
+#define IDLE_END 2
+
+struct notifier_block;
+void idle_notifier_register(struct notifier_block *n);
+void idle_notifier_unregister(struct notifier_block *n);
+
+void exit_idle(void);
+void enter_idle(void);
+
+#endif
diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h
index 11bf899de8aa..edfbe46a5e13 100644
--- a/include/asm-i386/processor.h
+++ b/include/asm-i386/processor.h
@@ -257,6 +257,14 @@ static inline void __mwait(unsigned long eax, unsigned long ecx)
                 : :"a" (eax), "c" (ecx));
 }
 
+static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
+{
+        /* "mwait %eax,%ecx;" */
+        asm volatile(
+                "sti; .byte 0x0f,0x01,0xc9;"
+                : :"a" (eax), "c" (ecx));
+}
+
 extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
 
 /* from system description table in BIOS.  Mostly for MCA use, but