[POWERPC] cell: Fix lost interrupts due to fasteoi handler

We may currently lose interrupts during SPE context switch, as we alter
the INT_Route register. Because the IIC uses a per-thread priority
status, changing the interrupt routing to a different thread means that
the IRQ is no longer masked by the priority status, so we end up with
two fasteoi IRQ handlers executing for the one irq_desc. The fasteoi
handler doesn't handle multiple IRQs, so drops the second one.

Fix this by using our own flow handler. This is based on
handle_edge_irq, but issues an eoi after IRQs are handled, and doesn't
do any mask/unmasking.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

diff --git a/arch/powerpc/platforms/cell/interrupt.c b/arch/powerpc/platforms/cell/interrupt.c
index 04f74f9..5bf7df1 100644 (file)
--- a/arch/powerpc/platforms/cell/interrupt.c
+++ b/arch/powerpc/platforms/cell/interrupt.c
@@ -35,6 +35,7 @@
 #include <linux/percpu.h>
 #include <linux/types.h>
 #include <linux/ioport.h>
+#include <linux/kernel_stat.h>
 
 #include <asm/io.h>
 #include <asm/pgtable.h>
@@ -231,6 +232,54 @@ static int iic_host_match(struct irq_host *h, struct device_node *node)
                                    "IBM,CBEA-Internal-Interrupt-Controller");
 }
 
+extern int noirqdebug;
+
+static void handle_iic_irq(unsigned int irq, struct irq_desc *desc)
+{
+       const unsigned int cpu = smp_processor_id();
+
+       spin_lock(&desc->lock);
+
+       desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
+
+       /*
+        * If we're currently running this IRQ, or its disabled,
+        * we shouldn't process the IRQ. Mark it pending, handle
+        * the necessary masking and go out
+        */
+       if (unlikely((desc->status & (IRQ_INPROGRESS | IRQ_DISABLED)) ||
+                   !desc->action)) {
+               desc->status |= IRQ_PENDING;
+               goto out_eoi;
+       }
+
+       kstat_cpu(cpu).irqs[irq]++;
+
+       /* Mark the IRQ currently in progress.*/
+       desc->status |= IRQ_INPROGRESS;
+
+       do {
+               struct irqaction *action = desc->action;
+               irqreturn_t action_ret;
+
+               if (unlikely(!action))
+                       goto out_eoi;
+
+               desc->status &= ~IRQ_PENDING;
+               spin_unlock(&desc->lock);
+               action_ret = handle_IRQ_event(irq, action);
+               if (!noirqdebug)
+                       note_interrupt(irq, desc, action_ret);
+               spin_lock(&desc->lock);
+
+       } while ((desc->status & (IRQ_PENDING | IRQ_DISABLED)) == IRQ_PENDING);
+
+       desc->status &= ~IRQ_INPROGRESS;
+out_eoi:
+       desc->chip->eoi(irq);
+       spin_unlock(&desc->lock);
+}
+
 static int iic_host_map(struct irq_host *h, unsigned int virq,
                        irq_hw_number_t hw)
 {
@@ -240,10 +289,10 @@ static int iic_host_map(struct irq_host *h, unsigned int virq,
                break;
        case IIC_IRQ_TYPE_IOEXC:
                set_irq_chip_and_handler(virq, &iic_ioexc_chip,
-                                        handle_fasteoi_irq);
+                                        handle_iic_irq);
                break;
        default:
-               set_irq_chip_and_handler(virq, &iic_chip, handle_fasteoi_irq);
+               set_irq_chip_and_handler(virq, &iic_chip, handle_iic_irq);
        }
        return 0;
 }