genirq: Mark polled irqs and defer the real handler

With the chip.end() function gone we might run into a situation where
a poll call runs and the real interrupt comes in, sees IRQ_INPROGRESS
and disables the line. That might be a perfect working one, which will
then be masked forever.

So mark them polled while the poll runs. When the real handler sees
IRQ_INPROGRESS it checks the poll flag and waits for the polling to
complete. Add the necessary amount of sanity checks to it to avoid
deadlocks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/irq.h b/include/linux/irq.h
index f5e9003..e32b64c 100644 (file)
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -71,6 +71,7 @@ typedef       void (*irq_flow_handler_t)(unsigned int irq,
 #define IRQ_SUSPENDED          0x04000000      /* IRQ has gone through suspend sequence */
 #define IRQ_ONESHOT            0x08000000      /* IRQ is not unmasked after hardirq */
 #define IRQ_NESTED_THREAD      0x10000000      /* IRQ is nested into another, no own handler thread */
+#define IRQ_POLL_INPROGRESS    0x20000000      /* IRQ poll is in progress */
 
 #define IRQF_MODIFY_MASK       \
        (IRQ_TYPE_SENSE_MASK | IRQ_NOPROBE | IRQ_NOREQUEST | \

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 622b55a..3125878 100644 (file)
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -448,6 +448,13 @@ out_unlock:
 }
 EXPORT_SYMBOL_GPL(handle_nested_irq);
 
+static bool irq_check_poll(struct irq_desc *desc)
+{
+       if (!(desc->status & IRQ_POLL_INPROGRESS))
+               return false;
+       return irq_wait_for_poll(desc);
+}
+
 /**
  *     handle_simple_irq - Simple and software-decoded IRQs.
  *     @irq:   the interrupt number
@@ -469,7 +476,9 @@ handle_simple_irq(unsigned int irq, struct irq_desc *desc)
        raw_spin_lock(&desc->lock);
 
        if (unlikely(desc->status & IRQ_INPROGRESS))
-               goto out_unlock;
+               if (!irq_check_poll(desc))
+                       goto out_unlock;
+
        desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
        kstat_incr_irqs_this_cpu(irq, desc);
 
@@ -510,7 +519,9 @@ handle_level_irq(unsigned int irq, struct irq_desc *desc)
        mask_ack_irq(desc);
 
        if (unlikely(desc->status & IRQ_INPROGRESS))
-               goto out_unlock;
+               if (!irq_check_poll(desc))
+                       goto out_unlock;
+
        desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
        kstat_incr_irqs_this_cpu(irq, desc);
 
@@ -558,7 +569,8 @@ handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc)
        raw_spin_lock(&desc->lock);
 
        if (unlikely(desc->status & IRQ_INPROGRESS))
-               goto out;
+               if (!irq_check_poll(desc))
+                       goto out;
 
        desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
        kstat_incr_irqs_this_cpu(irq, desc);
@@ -620,9 +632,11 @@ handle_edge_irq(unsigned int irq, struct irq_desc *desc)
         */
        if (unlikely((desc->status & (IRQ_INPROGRESS | IRQ_DISABLED)) ||
                    !desc->action)) {
-               desc->status |= (IRQ_PENDING | IRQ_MASKED);
-               mask_ack_irq(desc);
-               goto out_unlock;
+               if (!irq_check_poll(desc)) {
+                       desc->status |= (IRQ_PENDING | IRQ_MASKED);
+                       mask_ack_irq(desc);
+                       goto out_unlock;
+               }
        }
        kstat_incr_irqs_this_cpu(irq, desc);
 

diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index b5bfa24..0eff7e9 100644 (file)
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -28,6 +28,7 @@ extern void init_kstat_irqs(struct irq_desc *desc, int node, int nr);
 
 /* Resending of interrupts :*/
 void check_irq_resend(struct irq_desc *desc, unsigned int irq);
+bool irq_wait_for_poll(struct irq_desc *desc);
 
 #ifdef CONFIG_PROC_FS
 extern void register_irq_proc(unsigned int irq, struct irq_desc *desc);
@@ -47,16 +48,6 @@ extern int irq_select_affinity_usr(unsigned int irq, struct cpumask *mask);
 
 extern void irq_set_thread_affinity(struct irq_desc *desc);
 
-#ifndef CONFIG_GENERIC_HARDIRQS_NO_DEPRECATED
-static inline void irq_end(unsigned int irq, struct irq_desc *desc)
-{
-       if (desc->irq_data.chip && desc->irq_data.chip->end)
-               desc->irq_data.chip->end(irq);
-}
-#else
-static inline void irq_end(unsigned int irq, struct irq_desc *desc) { }
-#endif
-
 /* Inline functions for support of irq chips on slow busses */
 static inline void chip_bus_lock(struct irq_desc *desc)
 {

diff --git a/kernel/irq/spurious.c b/kernel/irq/spurious.c
index 56ff8ff..f749d29 100644 (file)
--- a/kernel/irq/spurious.c
+++ b/kernel/irq/spurious.c
@@ -25,12 +25,44 @@ static int irq_poll_cpu;
 static atomic_t irq_poll_active;
 
 /*
+ * We wait here for a poller to finish.
+ *
+ * If the poll runs on this CPU, then we yell loudly and return
+ * false. That will leave the interrupt line disabled in the worst
+ * case, but it should never happen.
+ *
+ * We wait until the poller is done and then recheck disabled and
+ * action (about to be disabled). Only if it's still active, we return
+ * true and let the handler run.
+ */
+bool irq_wait_for_poll(struct irq_desc *desc)
+{
+       if (WARN_ONCE(irq_poll_cpu == smp_processor_id(),
+                     "irq poll in progress on cpu %d for irq %d\n",
+                     smp_processor_id(), desc->irq_data.irq))
+               return false;
+
+#ifdef CONFIG_SMP
+       do {
+               raw_spin_unlock(&desc->lock);
+               while (desc->status & IRQ_INPROGRESS)
+                       cpu_relax();
+               raw_spin_lock(&desc->lock);
+       } while (desc->status & IRQ_INPROGRESS);
+       /* Might have been disabled in meantime */
+       return !(desc->status & IRQ_DISABLED) && desc->action;
+#else
+       return false;
+#endif
+}
+
+/*
  * Recovery handler for misrouted interrupts.
  */
 static int try_one_irq(int irq, struct irq_desc *desc, bool force)
 {
        struct irqaction *action;
-       int ok = 0, work = 0;
+       int ok = 0;
 
        raw_spin_lock(&desc->lock);
 
@@ -64,10 +96,9 @@ static int try_one_irq(int irq, struct irq_desc *desc, bool force)
                goto out;
        }
 
-       /* Honour the normal IRQ locking */
-       desc->status |= IRQ_INPROGRESS;
+       /* Honour the normal IRQ locking and mark it poll in progress */
+       desc->status |= IRQ_INPROGRESS | IRQ_POLL_INPROGRESS;
        do {
-               work++;
                desc->status &= ~IRQ_PENDING;
                raw_spin_unlock(&desc->lock);
                if (handle_IRQ_event(irq, action) != IRQ_NONE)
@@ -76,14 +107,7 @@ static int try_one_irq(int irq, struct irq_desc *desc, bool force)
                action = desc->action;
        }  while ((desc->status & IRQ_PENDING) && action);
 
-       desc->status &= ~IRQ_INPROGRESS;
-       /*
-        * If we did actual work for the real IRQ line we must let the
-        * IRQ controller clean up too
-        */
-       if (work > 1)
-               irq_end(irq, desc);
-
+       desc->status &= ~(IRQ_INPROGRESS | IRQ_POLL_INPROGRESS);
 out:
        raw_spin_unlock(&desc->lock);
        return ok;
@@ -238,6 +262,9 @@ try_misrouted_irq(unsigned int irq, struct irq_desc *desc,
 void note_interrupt(unsigned int irq, struct irq_desc *desc,
                    irqreturn_t action_ret)
 {
+       if (desc->status & IRQ_POLL_INPROGRESS)
+               return;
+
        if (unlikely(action_ret != IRQ_HANDLED)) {
                /*
                 * If we are seeing only the odd spurious IRQ caused by