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powerpc: Make decrementer interrupt robust against offlined CPUs 

With some implementations, it is possible that a timer interrupt
occurs every few seconds on an offline CPU. In this case, just
re-arm the decrementer and return immediately

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Benjamin Herrenschmidt 2011-03-29 14:51:10 +11:00
parent ecb78ab6f3
commit 963e5d3b76
1 changed files with 11 additions and 4 deletions
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15
arch/powerpc/kernel/time.c
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@ -577,14 +577,21 @@ void timer_interrupt(struct pt_regs * regs)
struct clock_event_device *evt = &decrementer->event;
u64 now;
/* Ensure a positive value is written to the decrementer, or else
* some CPUs will continue to take decrementer exceptions.
*/
set_dec(DECREMENTER_MAX);
/* Some implementations of hotplug will get timer interrupts while
* offline, just ignore these
*/
if (!cpu_online(smp_processor_id()))
return;
trace_timer_interrupt_entry(regs);
__get_cpu_var(irq_stat).timer_irqs++;
/* Ensure a positive value is written to the decrementer, or else
* some CPUs will continuue to take decrementer exceptions */
set_dec(DECREMENTER_MAX);
#if defined(CONFIG_PPC32) && defined(CONFIG_PMAC)
if (atomic_read(&ppc_n_lost_interrupts) != 0)
do_IRQ(regs);