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>

1 files changed, 2 insertions, 10 deletions

diff --git a/arch/x86/kernel/io_apic_32.c b/arch/x86/kernel/io_apic_32.c
index a40d54fc1fdd..4dc8600d9d20 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);