Revert "[PATCH] i386: add idle notifier"

This reverts commit 2ff2d3d747.

Uwe Bugla reports that he cannot mount a floppy drive any more, and Jiri
Slaby bisected it down to this commit.

Benjamin LaHaise also points out that this is a big hot-path, and that
interrupt delivery while idle is very common and should not go through
all these expensive gyrations.

Fix up conflicts in arch/i386/kernel/apic.c and arch/i386/kernel/irq.c
due to other unrelated irq changes.

Cc: Stephane Eranian <eranian@hpl.hp.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Andrew Morton <akpm@osdl.org>
Cc: Uwe Bugla <uwe.bugla@gmx.de>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/i386/kernel/apic.c

@@ -38,7 +38,6 @@
 #include <asm/hpet.h>
 #include <asm/i8253.h>
 #include <asm/nmi.h>
-#include <asm/idle.h>
 
 #include <mach_apic.h>
 #include <mach_apicdef.h>
@@ -561,7 +560,6 @@ void fastcall 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();
 	local_apic_timer_interrupt();
 	irq_exit();
@@ -1221,7 +1219,6 @@ 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
@@ -1245,7 +1242,6 @@ 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);

arch/i386/kernel/cpu/mcheck/p4.c

@@ -12,7 +12,6 @@
 #include <asm/system.h>
 #include <asm/msr.h>
 #include <asm/apic.h>
-#include <asm/idle.h>
 
 #include <asm/therm_throt.h>
 
@@ -60,7 +59,6 @@ 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();

arch/i386/kernel/irq.c

@@ -18,8 +18,6 @@
 #include <linux/cpu.h>
 #include <linux/delay.h>
 
-#include <asm/idle.h>
-
 #include <asm/apic.h>
 #include <asm/uaccess.h>
 
@@ -77,7 +75,6 @@ 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",

arch/i386/kernel/process.c

@@ -49,7 +49,6 @@
 #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
@@ -82,42 +81,6 @@ 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++;
@@ -168,7 +131,6 @@ EXPORT_SYMBOL(default_idle);
  */
 static void poll_idle (void)
 {
-	local_irq_enable();
 	cpu_relax();
 }
 
@@ -229,16 +191,7 @@ 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();
 		}
 		tick_nohz_restart_sched_tick();
 		preempt_enable_no_resched();
@@ -293,11 +246,7 @@ void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
 		__monitor((void *)&current_thread_info()->flags, 0, 0);
 		smp_mb();
 		if (!need_resched())
-			__sti_mwait(eax, ecx);
+			__mwait(eax, ecx);
-		else
-			local_irq_enable();
-	} else {
-		local_irq_enable();
 	}
 }
 

arch/i386/kernel/smp.c

@@ -23,7 +23,6 @@
 
 #include <asm/mtrr.h>
 #include <asm/tlbflush.h>
-#include <asm/idle.h>
 #include <mach_apic.h>
 
 /*
@@ -624,7 +623,6 @@ 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();

include/asm-i386/idle.h

@@ -1,14 +0,0 @@
-#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

include/asm-i386/processor.h

@@ -257,14 +257,6 @@ 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