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, 3 deletions

diff --git a/sys/amd64/isa/atpic.c b/sys/amd64/isa/atpic.c
index 3a88eda4ef10..d9792eb8fcde 100644
--- a/sys/amd64/isa/atpic.c
+++ b/sys/amd64/isa/atpic.c
@@ -107,9 +107,10 @@ inthand_t
 
 #define	ATPIC(io, base, eoi, imenptr)					\
      	{ { atpic_enable_source, atpic_disable_source, (eoi),		\
-	    atpic_enable_intr, atpic_vector, atpic_source_pending, NULL, \
-	    atpic_resume, atpic_config_intr, atpic_assign_cpu }, (io),  \
-	    (base), IDT_IO_INTS + (base), (imenptr) }
+	    atpic_enable_intr, atpic_disable_intr, atpic_vector,	\
+	    atpic_source_pending, NULL,	atpic_resume, atpic_config_intr,\
+	    atpic_assign_cpu }, (io), (base), IDT_IO_INTS + (base),	\
+	    (imenptr) }
 
 #define	INTSRC(irq)							\
 	{ { &atpics[(irq) / 8].at_pic }, IDTVEC(atpic_intr ## irq ),	\
@@ -137,6 +138,7 @@ static void atpic_disable_source(struct intsrc *isrc, int eoi);
 static void atpic_eoi_master(struct intsrc *isrc);
 static void atpic_eoi_slave(struct intsrc *isrc);
 static void atpic_enable_intr(struct intsrc *isrc);
+static void atpic_disable_intr(struct intsrc *isrc);
 static int atpic_vector(struct intsrc *isrc);
 static void atpic_resume(struct pic *pic);
 static int atpic_source_pending(struct intsrc *isrc);
@@ -266,6 +268,12 @@ atpic_enable_intr(struct intsrc *isrc)
 {
 }
 
+static void
+atpic_disable_intr(struct intsrc *isrc)
+{
+}
+
+
 static int
 atpic_vector(struct intsrc *isrc)
 {