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x86: apic - introduce dummy apic operations

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Impact: refactor, speed up and robustize code

In case if apic was disabled by kernel option
or by hardware limits we can use dummy operations
in apic->write to simplify the ack_APIC_irq() code.

At the lame time the patch fixes the missed EOI in
do_IRQ function (which has place if kernel is compiled
as X86-32 and interrupt without handler happens where
apic was not asked to be disabled via kernel option).

Note that native_apic_write_dummy() consists of
WARN_ON_ONCE to catch any buggy writes on enabled
APICs. Could be removed after some time of testing.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
LKML-Reference: <20090412165058.724788431@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Cyrill Gorcunov
2009-04-12 20:47:41 +04:00
committed by Ingo Molnar
parent c0eaa4536f
commit 08306ce61d
3 changed files with 28 additions and 9 deletions
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10
arch/x86/kernel/irq.c
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@ -27,7 +27,6 @@ void ack_bad_irq(unsigned int irq)
if (printk_ratelimit())
pr_err("unexpected IRQ trap at vector %02x\n", irq);
#ifdef CONFIG_X86_LOCAL_APIC
/*
* Currently unexpected vectors happen only on SMP and APIC.
* We _must_ ack these because every local APIC has only N
@ -37,9 +36,7 @@ void ack_bad_irq(unsigned int irq)
* completely.
* But only ack when the APIC is enabled -AK
*/
if (cpu_has_apic)
ack_APIC_irq();
#endif
ack_APIC_irq();
}
#define irq_stats(x) (&per_cpu(irq_stat, x))
@ -214,10 +211,7 @@ unsigned int __irq_entry do_IRQ(struct pt_regs *regs)
irq = __get_cpu_var(vector_irq)[vector];
if (!handle_irq(irq, regs)) {
#ifdef CONFIG_X86_64
if (!disable_apic)
ack_APIC_irq();
#endif
ack_APIC_irq();
if (printk_ratelimit())
pr_emerg("%s: %d.%d No irq handler for vector (irq %d)\n",