Commit 64fcbac1 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86: Simplify timer_ack magic in time_32.c 



Let the compiler optimize the timer_ack magic away in the 32bit timer
interrupt and put the same code into time_64.c. It's optimized out for
CONFIG_X86_IO_APIC on 32bit and for 64bit because timer_ack is const 0
in both cases.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent dd3e6e8c

arch/x86/include/asm/timer.h

+4 −2
Original line number Diff line number Diff line
@@ -9,11 +9,13 @@ 


unsigned long long native_sched_clock(void);

unsigned long native_calibrate_tsc(void);

extern int recalibrate_cpu_khz(void);



#ifdef CONFIG_X86_32

#if defined(CONFIG_X86_32) && defined(CONFIG_X86_IO_APIC)

extern int timer_ack;

#else

# define timer_ack (0)

#endif

extern int recalibrate_cpu_khz(void);



extern int no_timer_check;

arch/x86/kernel/time_32.c

+3 −2
Original line number Diff line number Diff line
@@ -23,7 +23,9 @@ 
#include <asm/time.h>

#include <asm/nmi.h>



#if defined(CONFIG_X86_32) && defined(CONFIG_X86_IO_APIC)

int timer_ack;

#endif



unsigned long profile_pc(struct pt_regs *regs)

{
@@ -60,7 +62,7 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id) 
	/* Keep nmi watchdog up to date */

	inc_irq_stat(irq0_irqs);



#ifdef CONFIG_X86_IO_APIC

	/* Optimized out for !IO_APIC and x86_64 */

	if (timer_ack) {

		/*

		 * Subtle, when I/O APICs are used we have to ack timer IRQ
@@ -73,7 +75,6 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id) 
		inb(PIC_MASTER_POLL);

		spin_unlock(&i8259A_lock);

	}

#endif



	global_clock_event->event_handler(global_clock_event);

arch/x86/kernel/time_64.c

+14 −0
Original line number Diff line number Diff line
@@ -51,6 +51,20 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id) 
{

	inc_irq_stat(irq0_irqs);



	/* Optimized out for !IO_APIC and x86_64 */

	if (timer_ack) {

		/*

		 * Subtle, when I/O APICs are used we have to ack timer IRQ

		 * manually to deassert NMI lines for the watchdog if run

		 * on an 82489DX-based system.

		 */

		spin_lock(&i8259A_lock);

		outb(0x0c, PIC_MASTER_OCW3);

		/* Ack the IRQ; AEOI will end it automatically. */

		inb(PIC_MASTER_POLL);

		spin_unlock(&i8259A_lock);

	}



	global_clock_event->event_handler(global_clock_event);



#ifdef CONFIG_MCA

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