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Date: Wed, 26 Sep 2012 12:14:18 +0530 From: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com> To: Chuansheng Liu <chuansheng.liu@...el.com> CC: tglx@...utronix.de, mingo@...hat.com, x86@...nel.org, linux-kernel@...r.kernel.org, yanmin_zhang@...ux.intel.com, Ingo Molnar <mingo@...nel.org> Subject: Re: [PATCH] x86/fixup_irq: Clean the offlining CPU from the irq affinity mask On 09/26/2012 08:02 PM, Chuansheng Liu wrote: > > When one CPU is going offline, and fixup_irqs() will re-set the > irq affinity in some cases, we should clean the offlining CPU from > the irq affinity. > > The reason is setting offlining CPU as of the affinity is useless. > Moreover, the smp_affinity value will be confusing when the > offlining CPU come back again. > > Example: > For irq 93 with 4 CPUS, the default affinity f(1111), > normal cases: 4 CPUS will receive the irq93 interrupts. > > When echo 0 > /sys/devices/system/cpu/cpu3/online, just CPU0,1,2 will > receive the interrupts. > > But after the CPU3 is online again, we will not set affinity,the result > will be: > the smp_affinity is f, but still just CPU0,1,2 can receive the interrupts. > > So we should clean the offlining CPU from irq affinity mask > in fixup_irqs(). > > Signed-off-by: liu chuansheng <chuansheng.liu@...el.com> > --- > arch/x86/kernel/irq.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c > index d44f782..671d462 100644 > --- a/arch/x86/kernel/irq.c > +++ b/arch/x86/kernel/irq.c > @@ -239,6 +239,7 @@ void fixup_irqs(void) > struct irq_desc *desc; > struct irq_data *data; > struct irq_chip *chip; > + int cpu = smp_processor_id(); > > for_each_irq_desc(irq, desc) { > int break_affinity = 0; > @@ -271,7 +272,8 @@ void fixup_irqs(void) > if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) { > break_affinity = 1; > affinity = cpu_online_mask; > - } > + } else if (cpumask_test_cpu(cpu, data->affinity)) > + cpumask_clear_cpu(cpu, data->affinity); > You meant to use 'affinity' (instead of data->affinity) in the above 2 statements right? Note that we do chip->irq_set_affinity(data, affinity, true); further down. Regards, Srivatsa S. Bhat > chip = irq_data_get_irq_chip(data); > if (!irqd_can_move_in_process_context(data) && chip->irq_mask) > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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