Revert "x86: fix ioapic bug again"

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From: Linux Kernel Mailing List
Date: Thursday, June 12, 2008 - 1:59 pm

Gitweb:     http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=0b6a39...
Commit:     0b6a39f7ebcb1c82587ce35b401c513eed41ac5c
Parent:     86b2b70e156203149c3861455feec54bc4906e6d
Author:     Ingo Molnar <mingo@elte.hu>
AuthorDate: Mon Jun 9 13:29:43 2008 +0200
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Thu Jun 12 21:26:28 2008 +0200

    Revert "x86: fix ioapic bug again"
    
    This reverts commit 6e908947b4995bc0e551a8257c586d5c3e428201.
    
    Németh Márton reported:
    
    | there is a problem in 2.6.26-rc3 which was not there in case of
    | 2.6.25: the CPU wakes up ~90,000 times per sec instead of ~60 per sec.
    |
    | I also "git bisected" the problem, the result is:
    |
    | 6e908947b4995bc0e551a8257c586d5c3e428201 is first bad commit
    | commit 6e908947b4995bc0e551a8257c586d5c3e428201
    | Author: Ingo Molnar <mingo@elte.hu>
    | Date:   Fri Mar 21 14:32:36 2008 +0100
    |
    |     x86: fix ioapic bug again
    
    the original problem is fixed by Maciej W. Rozycki in the tip/x86/apic
    branch (confirmed by Márton), but those changes are too intrusive for
    v2.6.26 so we'll go for the less intrusive (repeated) revert now.
    
    Reported-and-bisected-by: Németh Márton <nm127@freemail.hu>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/kernel/io_apic_32.c |   12 ++----------
 arch/x86/kernel/nmi_32.c     |    9 ++-------
 2 files changed, 4 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kernel/io_apic_32.c b/arch/x86/kernel/io_apic_32.c
index a40d54f..4dc8600 100644
--- a/arch/x86/kernel/io_apic_32.c
+++ b/arch/x86/kernel/io_apic_32.c
@@ -2130,14 +2130,10 @@ static inline void __init check_timer(void)
 {
 	int apic1, pin1, apic2, pin2;
 	int vector;
-	unsigned int ver;
 	unsigned long flags;
 
 	local_irq_save(flags);
 
-	ver = apic_read(APIC_LVR);
-	ver = GET_APIC_VERSION(ver);
-
 	/*
 	 * get/set the timer IRQ vector:
 	 */
@@ -2150,15 +2146,11 @@ static inline void __init check_timer(void)
 	 * mode for the 8259A whenever interrupts are routed
 	 * through I/O APICs.  Also IRQ0 has to be enabled in
 	 * the 8259A which implies the virtual wire has to be
-	 * disabled in the local APIC.  Finally timer interrupts
-	 * need to be acknowledged manually in the 8259A for
-	 * timer_interrupt() and for the i82489DX when using
-	 * the NMI watchdog.
+	 * disabled in the local APIC.
 	 */
 	apic_write_around(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_EXTINT);
 	init_8259A(1);
-	timer_ack = !cpu_has_tsc;
-	timer_ack |= (nmi_watchdog == NMI_IO_APIC && !APIC_INTEGRATED(ver));
+	timer_ack = 1;
 	if (timer_over_8254 > 0)
 		enable_8259A_irq(0);
 
diff --git a/arch/x86/kernel/nmi_32.c b/arch/x86/kernel/nmi_32.c
index 11b14bb..84160f7 100644
--- a/arch/x86/kernel/nmi_32.c
+++ b/arch/x86/kernel/nmi_32.c
@@ -26,7 +26,6 @@
 
 #include <asm/smp.h>
 #include <asm/nmi.h>
-#include <asm/timer.h>
 
 #include "mach_traps.h"
 
@@ -82,7 +81,7 @@ int __init check_nmi_watchdog(void)
 
 	prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);
 	if (!prev_nmi_count)
-		goto error;
+		return -1;
 
 	printk(KERN_INFO "Testing NMI watchdog ... ");
 
@@ -119,7 +118,7 @@ int __init check_nmi_watchdog(void)
 	if (!atomic_read(&nmi_active)) {
 		kfree(prev_nmi_count);
 		atomic_set(&nmi_active, -1);
-		goto error;
+		return -1;
 	}
 	printk("OK.\n");
 
@@ -130,10 +129,6 @@ int __init check_nmi_watchdog(void)
 
 	kfree(prev_nmi_count);
 	return 0;
-error:
-	timer_ack = !cpu_has_tsc;
-
-	return -1;
 }
 
 static int __init setup_nmi_watchdog(char *str)
--
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Revert "x86: fix ioapic bug again", Linux Kernel Mailing ..., (Thu Jun 12, 1:59 pm)