[PATCH 01/18] powerpc: Make decrementer interrupt robust against offlined CPUs
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2011-03-08 06:37:40
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
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> --- arch/powerpc/kernel/time.c | 15 +++++++++++---- 1 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 09d31db..ecebc7c 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c@@ -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 continuue 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);
--
1.7.1