lkml.org 
[lkml]   [2009]   [May]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[PATCH v2] [BUGFIX] x86/x86_64: fix CPU offlining triggered active device IRQ interrruption

    Impact: Eliminates an issue that can leave the system in an
    unusable state.

    This patch addresses an issue where device generated IRQs
    are no longer seen by the kernel following IRQ affinity
    migration while the device is generating IRQs at a high rate.

    I have been able to consistently reproduce the problem on
    some of our systems by running the following script (VICTIM_IRQ
    specifies the IRQ for the aic94xx device) while a single instance
    of the command
    # while true; do find / -exec file {} \;; done
    is keeping the filesystem activity and IRQ rate reasonably high.

    #!/bin/sh

    SYS_CPU_DIR=/sys/devices/system/cpu
    VICTIM_IRQ=25
    IRQ_MASK=f0

    iteration=0
    while true; do
    echo $iteration
    echo $IRQ_MASK > /proc/irq/$VICTIM_IRQ/smp_affinity
    for cpudir in $SYS_CPU_DIR/cpu[1-9] $SYS_CPU_DIR/cpu??; do
    echo 0 > $cpudir/online
    done
    for cpudir in $SYS_CPU_DIR/cpu[1-9] $SYS_CPU_DIR/cpu??; do
    echo 1 > $cpudir/online
    done
    iteration=`expr $iteration + 1`
    done

    The root cause is a known issue already addressed for some
    code paths [e.g. ack_apic_level() and the now obsolete
    migrate_irq_remapped_level_desc()] where the ioapic can
    misbehave when the I/O redirection table register is written
    while the Remote IRR bit is set.

    The proposed fix uses the same avoidance method and much
    of same code that the Interrupt Remapping code previously
    used to avoid the same problem.

    Successfully tested with Ingo's linux-2.6-tip (32 and 64-bit
    builds) on the IBM x460, x3550 M2, x3850, and x3950 M2.

    v2: modified to integrate with Yinghai Lu's
    "irq: change ->set_affinity() to return status" changes
    to intersecting/related code.

    Signed-off-by: Gary Hade <garyhade@us.ibm.com>

    ---
    arch/x86/kernel/apic/io_apic.c | 68 ++++++++++++++++++++++++++++++-
    1 file changed, 67 insertions(+), 1 deletion(-)

    Index: linux-2.6-tip/arch/x86/kernel/apic/io_apic.c
    ===================================================================
    --- linux-2.6-tip.orig/arch/x86/kernel/apic/io_apic.c 2009-05-14 14:11:00.000000000 -0700
    +++ linux-2.6-tip/arch/x86/kernel/apic/io_apic.c 2009-05-14 14:11:32.000000000 -0700
    @@ -2296,7 +2296,8 @@ set_desc_affinity(struct irq_desc *desc,
    }

    static int
    -set_ioapic_affinity_irq_desc(struct irq_desc *desc, const struct cpumask *mask)
    +set_ioapic_irq_affinity_desc(struct irq_desc *desc,
    + const struct cpumask *mask)
    {
    struct irq_cfg *cfg;
    unsigned long flags;
    @@ -2320,6 +2321,71 @@ set_ioapic_affinity_irq_desc(struct irq_
    return ret;
    }

    +static void
    +delayed_irq_move(struct work_struct *work)
    +{
    + unsigned int irq;
    + struct irq_desc *desc;
    +
    + for_each_irq_desc(irq, desc) {
    + if (desc->status & IRQ_MOVE_PENDING) {
    + unsigned long flags;
    +
    + spin_lock_irqsave(&desc->lock, flags);
    + if (!desc->chip->set_affinity ||
    + !(desc->status & IRQ_MOVE_PENDING)) {
    + desc->status &= ~IRQ_MOVE_PENDING;
    + spin_unlock_irqrestore(&desc->lock, flags);
    + continue;
    + }
    + desc->chip->set_affinity(irq, desc->pending_mask);
    + spin_unlock_irqrestore(&desc->lock, flags);
    + }
    + }
    +}
    +
    +static DECLARE_DELAYED_WORK(delayed_irq_move_work, delayed_irq_move);
    +
    +static int
    +set_ioapic_irq_affinity_level_desc(struct irq_desc *desc)
    +{
    + struct irq_cfg *cfg = desc->chip_data;
    + int ret = -1;
    +
    + mask_IO_APIC_irq_desc(desc);
    + if (io_apic_level_ack_pending(cfg)) {
    + /*
    + * Interrupt in progress. Migrating irq now will change
    + * the vector information in the IO-APIC RTE which will
    + * confuse the EOI broadcast performed by cpu.
    + * So, we delay the IRQ migration.
    + */
    + schedule_delayed_work(&delayed_irq_move_work, 1);
    + ret = 0;
    + goto unmask;
    + }
    +
    + /* Interrupt not in progress. We can change the vector
    + * information in the IO-APIC RTE. */
    + ret = set_ioapic_irq_affinity_desc(desc, desc->pending_mask);
    + desc->status &= ~IRQ_MOVE_PENDING;
    +unmask:
    + unmask_IO_APIC_irq_desc(desc);
    + return ret;
    +}
    +
    +static int
    +set_ioapic_affinity_irq_desc(struct irq_desc *desc,
    + const struct cpumask *mask)
    +{
    + if (desc->status & IRQ_LEVEL) {
    + desc->status |= IRQ_MOVE_PENDING;
    + cpumask_copy(desc->pending_mask, mask);
    + return set_ioapic_irq_affinity_level_desc(desc);
    + }
    + return set_ioapic_irq_affinity_desc(desc, mask);
    +}
    +
    static int
    set_ioapic_affinity_irq(unsigned int irq, const struct cpumask *mask)
    {

    \
     
     \ /
      Last update: 2009-05-15 01:05    [W:0.035 / U:1.868 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site