On 1/6/14, Prarit Bhargava <pra...@redhat.com> wrote: > I tested this by doing a continuous loop of booting a system, downing all > cpus, and then rebooting. Before every reboot I grepped the dmesg log for > the do_IRQ warning to see if there were any additional do_IRQ warnings and > I do not see any after applying this patch. I also tested on several > small and medium sized boxes to confirm that cpu hotplug still works there > too and do not see any issues. Please note that this patchset was tested > in conjunction with > > http://marc.info/?l=linux-edac&m=138783131400902&w=2 > > and > > http://marc.info/?l=linux-kernel&m=138871006718478&w=2 > > in order to get cpu hotplug working. > > I'm redoing some additional stability testing (with the additional 2 line > change in this version of the patch) after down'ing all cpus and > bringing them back into service, however, I don't expect to see any new > issues. > > P. > > ----8<---- > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=64831 > > When downing a cpu it is possible that there are unhandled irqs left in > the APIC IRR register. The following code path shows how the problem > can occur: > > 1. CPU 5 is to go down. > 2. cpu_disable() on CPU 5 executes with interrupt flag cleared by > local_irq_save() via stop_machine(). > 3. IRQ 12 asserts on CPU 5, setting IRR but not ISR because interrupt > flag is cleared (CPU unabled to handle the irq) > 4. IRQs are migrated off of CPU 5, and the vectors' irqs are set to -1. > 5. stop_machine() finishes cpu_disable() > 6. cpu_die() for CPU 5 executes in normal context. > 7. CPU 5 attempts to handle IRQ 12 because the IRR is set for IRQ 12. The > code attempts to find the vector's IRQ and cannot because it has been set to > -1. > 8. do_IRQ warning displays warning about CPU 5 IRQ 12. > > When this happens, do_IRQ() spits out a warning like > > kernel: [ 614.414443] do_IRQ: 5.124 No irq handler for vector (irq -1) > > I added a debug printk to output which CPU & vector was retriggered and > discovered that that we are getting bogus events. I see a 100% correlation > between this debug printk in fixup_irqs() and the do_IRQ() warning. > > This patchset resolves this by adding definitions for VECTOR_UNDEFINED(-1) > and > VECTOR_RETRIGGERED(-2) and modifying the code to use them. > > [v2]: sent with more detailed commit message > [v3]: set vector_irq[irq] back to VECTOR_UNDEFINED after call in do_IRQ() > > Signed-off-by: Prarit Bhargava <pra...@redhat.com> > Cc: Thomas Gleixner <t...@linutronix.de> > Cc: Ingo Molnar <mi...@redhat.com> > Cc: "H. Peter Anvin" <h...@zytor.com> > Cc: x...@kernel.org > Cc: Michel Lespinasse <wal...@google.com> > Cc: Andi Kleen <a...@linux.intel.com> > Cc: Seiji Aguchi <seiji.agu...@hds.com> > Cc: Yang Zhang <yang.z.zh...@intel.com> > Cc: Paul Gortmaker <paul.gortma...@windriver.com> > Cc: janet.mor...@intel.com > Cc: tony.l...@intel.com > Cc: ruiv.w...@gmail.com > --- > arch/x86/include/asm/hw_irq.h | 2 ++ > arch/x86/kernel/apic/io_apic.c | 13 +++++++------ > arch/x86/kernel/irq.c | 20 ++++++++++++++------ > arch/x86/kernel/irqinit.c | 4 ++-- > 4 files changed, 25 insertions(+), 14 deletions(-) > > diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h > index 92b3bae..22c425e 100644 > --- a/arch/x86/include/asm/hw_irq.h > +++ b/arch/x86/include/asm/hw_irq.h > @@ -188,6 +188,8 @@ extern __visible void smp_invalidate_interrupt(struct > pt_regs *); > > extern void (*__initconst > interrupt[NR_VECTORS-FIRST_EXTERNAL_VECTOR])(void); > > +#define VECTOR_UNDEFINED -1 > +#define VECTOR_RETRIGGERED -2 > typedef int vector_irq_t[NR_VECTORS]; > DECLARE_PER_CPU(vector_irq_t, vector_irq); > extern void setup_vector_irq(int cpu); > diff --git a/arch/x86/kernel/apic/io_apic.c > b/arch/x86/kernel/apic/io_apic.c > index e63a5bd..6e1541c 100644 > --- a/arch/x86/kernel/apic/io_apic.c > +++ b/arch/x86/kernel/apic/io_apic.c > @@ -1143,7 +1143,8 @@ next: > goto next; > > for_each_cpu_and(new_cpu, tmp_mask, cpu_online_mask) > - if (per_cpu(vector_irq, new_cpu)[vector] != -1) > + if (per_cpu(vector_irq, new_cpu)[vector] > > + VECTOR_UNDEFINED) > goto next; > /* Found one! */ > current_vector = vector; > @@ -1183,7 +1184,7 @@ static void __clear_irq_vector(int irq, struct irq_cfg > *cfg) > > vector = cfg->vector; > for_each_cpu_and(cpu, cfg->domain, cpu_online_mask) > - per_cpu(vector_irq, cpu)[vector] = -1; > + per_cpu(vector_irq, cpu)[vector] = VECTOR_UNDEFINED; > > cfg->vector = 0; > cpumask_clear(cfg->domain); > @@ -1195,7 +1196,7 @@ static void __clear_irq_vector(int irq, struct irq_cfg > *cfg) > vector++) { > if (per_cpu(vector_irq, cpu)[vector] != irq) > continue; > - per_cpu(vector_irq, cpu)[vector] = -1; > + per_cpu(vector_irq, cpu)[vector] = VECTOR_UNDEFINED; > break; > } > } > @@ -1228,12 +1229,12 @@ void __setup_vector_irq(int cpu) > /* Mark the free vectors */ > for (vector = 0; vector < NR_VECTORS; ++vector) { > irq = per_cpu(vector_irq, cpu)[vector]; > - if (irq < 0) > + if (irq <= VECTOR_UNDEFINED) > continue; > > cfg = irq_cfg(irq); > if (!cpumask_test_cpu(cpu, cfg->domain)) > - per_cpu(vector_irq, cpu)[vector] = -1; > + per_cpu(vector_irq, cpu)[vector] = VECTOR_UNDEFINED; > } > raw_spin_unlock(&vector_lock); > } > @@ -2208,7 +2209,7 @@ asmlinkage void smp_irq_move_cleanup_interrupt(void) > struct irq_cfg *cfg; > irq = __this_cpu_read(vector_irq[vector]); > > - if (irq == -1) > + if (irq <= VECTOR_UNDEFINED) > continue; > > desc = irq_to_desc(irq); > diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c > index 22d0687..8e9f0aa 100644 > --- a/arch/x86/kernel/irq.c > +++ b/arch/x86/kernel/irq.c > @@ -193,9 +193,13 @@ __visible unsigned int __irq_entry do_IRQ(struct > pt_regs *regs) > if (!handle_irq(irq, regs)) { > ack_APIC_irq(); > > - if (printk_ratelimit()) > - pr_emerg("%s: %d.%d No irq handler for vector (irq > %d)\n", > - __func__, smp_processor_id(), vector, irq); > + if (irq != VECTOR_RETRIGGERED) > + pr_emerg_ratelimited("%s: %d.%d No irq handler for > vector (irq %d)\n", > + __func__, smp_processor_id(), > + vector, irq); > + else > + __this_cpu_write(vector_irq[vector], > + VECTOR_UNDEFINED); > } > > irq_exit(); > @@ -344,7 +348,7 @@ void fixup_irqs(void) > for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) { > unsigned int irr; > > - if (__this_cpu_read(vector_irq[vector]) < 0) > + if (__this_cpu_read(vector_irq[vector]) <= VECTOR_UNDEFINED) > continue; > > irr = apic_read(APIC_IRR + (vector / 32 * 0x10)); > @@ -355,11 +359,15 @@ void fixup_irqs(void) > data = irq_desc_get_irq_data(desc); > chip = irq_data_get_irq_chip(data); > raw_spin_lock(&desc->lock); > - if (chip->irq_retrigger) > + if (chip->irq_retrigger) { > chip->irq_retrigger(data); > + __this_cpu_write(vector_irq[vector], > + VECTOR_RETRIGGERED); > + } > raw_spin_unlock(&desc->lock); > } > - __this_cpu_write(vector_irq[vector], -1); > + if (__this_cpu_read(vector_irq[vector]) != VECTOR_RETRIGGERED) > + __this_cpu_write(vector_irq[vector], VECTOR_UNDEFINED); > } > } > #endif > diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c > index a2a1fbc..7f50156 100644 > --- a/arch/x86/kernel/irqinit.c > +++ b/arch/x86/kernel/irqinit.c > @@ -52,7 +52,7 @@ static struct irqaction irq2 = { > }; > > DEFINE_PER_CPU(vector_irq_t, vector_irq) = { > - [0 ... NR_VECTORS - 1] = -1, > + [0 ... NR_VECTORS - 1] = VECTOR_UNDEFINED, > }; > > int vector_used_by_percpu_irq(unsigned int vector) > @@ -60,7 +60,7 @@ int vector_used_by_percpu_irq(unsigned int vector) > int cpu; > > for_each_online_cpu(cpu) { > - if (per_cpu(vector_irq, cpu)[vector] != -1) > + if (per_cpu(vector_irq, cpu)[vector] > VECTOR_UNDEFINED) > return 1; > } > > -- > 1.7.9.3 > >
If it precisely catches the remaining IRR, then it is something good to have. Reviewed-by: Rui Wang <rui.y.w...@intel.com> Thanks Rui -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
