[PATCH] disable LAPIC completely for offline CPU

From: Shaohua Li
Date: Wed Nov 23 2005 - 18:56:15 EST


Disabling LAPIC timer isn't sufficient. In some situations, such as we
enabled NMI watchdog, there is still unexpected interrupt (such as NMI)
invoked in offline CPU. This also avoids offline CPU receives spurious
interrupt and anything similar.

Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
---

linux-2.6.14-root/arch/i386/kernel/smpboot.c | 3 +--
linux-2.6.14-root/arch/x86_64/kernel/smpboot.c | 2 +-
2 files changed, 2 insertions(+), 3 deletions(-)

diff -puN arch/x86_64/kernel/smpboot.c~cpuhp-disable-lapic arch/x86_64/kernel/smpboot.c
--- linux-2.6.14/arch/x86_64/kernel/smpboot.c~cpuhp-disable-lapic 2005-11-23 19:27:36.000000000 -0800
+++ linux-2.6.14-root/arch/x86_64/kernel/smpboot.c 2005-11-23 19:28:27.000000000 -0800
@@ -1181,7 +1181,7 @@ int __cpu_disable(void)
if (cpu == 0)
return -EBUSY;

- disable_APIC_timer();
+ disable_local_APIC();

/*
* HACK:
diff -puN arch/i386/kernel/smpboot.c~cpuhp-disable-lapic arch/i386/kernel/smpboot.c
--- linux-2.6.14/arch/i386/kernel/smpboot.c~cpuhp-disable-lapic 2005-11-23 19:28:38.000000000 -0800
+++ linux-2.6.14-root/arch/i386/kernel/smpboot.c 2005-11-23 19:30:05.000000000 -0800
@@ -1338,8 +1338,7 @@ int __cpu_disable(void)
if (cpu == 0)
return -EBUSY;

- /* We enable the timer again on the exit path of the death loop */
- disable_APIC_timer();
+ disable_local_APIC();
/* Allow any queued timer interrupts to get serviced */
local_irq_enable();
mdelay(1);
_


-
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