Minor fixes and tweaks to the x86 interrupt code:

- Split the intr_table_lock into an sx lock used for most things, and a
  spin lock to protect intrcnt_index.  Originally I had this as a spin lock
  so interrupt code could use it to lookup sources.  However, we don't
  actually do that because it would add a lot of overhead to interrupts,
  and if we ever do support removing interrupt sources, we can use other
  means to safely do so w/o locking in the interrupt handling code.
- Replace is_enabled (boolean) with is_handlers (a count of handlers) to
  determine if a source is enabled or not.  This allows us to notice when
  a source is no longer in use.  When that happens, we now invoke a new
  PIC method (pic_disable_intr()) to inform the PIC driver that the
  source is no longer in use.  The I/O APIC driver frees the APIC IDT
  vector when this happens.  The MSI driver no longer needs to have a
  hack to clear is_enabled during msi_alloc() and msix_alloc() as a result
  of this change as well.
- Add an apic_disable_vector() to reset an IDT vector back to Xrsvd to
  complement apic_enable_vector() and use it in the I/O APIC and MSI code
  when freeing an IDT vector.
- Add a new nexus hook: nexus_add_irq() to ask the nexus driver to add an
  IRQ to its irq_rman.  The MSI code uses this when it creates new
  interrupt sources to let the nexus know about newly valid IRQs.
  Previously the msi_alloc() and msix_alloc() passed some extra stuff
  back to the nexus methods which then added the IRQs.  This approach is
  a bit cleaner.
- Change the MSI sx lock to a mutex.  If we need to create new sources,
  drop the lock, create the required number of sources, then get the lock
  and try the allocation again.

1 files changed, 11 insertions, 15 deletions

diff --git a/sys/amd64/amd64/nexus.c b/sys/amd64/amd64/nexus.c
index 108abc117969..b5498b7d1e18 100644
--- a/sys/amd64/amd64/nexus.c
+++ b/sys/amd64/amd64/nexus.c
@@ -503,15 +503,20 @@ nexus_delete_resource(device_t dev, device_t child, int type, int rid)
 	resource_list_delete(rl, type, rid);
 }
 
+/* Called from the MSI code to add new IRQs to the IRQ rman. */
+void
+nexus_add_irq(u_long irq)
+{
+
+	if (rman_manage_region(&irq_rman, irq, irq) != 0)
+		panic("%s: failed", __func__);
+}
+
 static int
 nexus_alloc_msix(device_t pcib, device_t dev, int *irq)
 {
-	int error, new;
 
-	error = msix_alloc(dev, irq, &new);
-	if (new)
-		rman_manage_region(&irq_rman, *irq, *irq);
-	return (error);
+	return (msix_alloc(dev, irq));
 }
 
 static int
@@ -524,17 +529,8 @@ nexus_release_msix(device_t pcib, device_t dev, int irq)
 static int
 nexus_alloc_msi(device_t pcib, device_t dev, int count, int maxcount, int *irqs)
 {
-	int error, i, newirq, newcount;
-
-	/* First alloc the messages. */
-	error = msi_alloc(dev, count, maxcount, irqs, &newirq, &newcount);
 
-	/* Always add any new IRQs to the rman, even on failure. */
-	for (i = 0; i < newcount; i++)
-		rman_manage_region(&irq_rman, irqs[newirq + i],
-		    irqs[newirq + i]);
-
-	return (error);
+	return (msi_alloc(dev, count, maxcount, irqs));
 }
 
 static int