Compromise for critical*()/cpu_critical*() recommit. Cleanup the interrupt

disablement assumptions in kern_fork.c by adding another API call,
cpu_critical_fork_exit().  Cleanup the td_savecrit field by moving it
from MI to MD.  Temporarily move cpu_critical*() from <arch>/include/cpufunc.h
to <arch>/<arch>/critical.c (stage-2 will clean this up).

Implement interrupt deferral for i386 that allows interrupts to remain
enabled inside critical sections.  This also fixes an IPI interlock bug,
and requires uses of icu_lock to be enclosed in a true interrupt disablement.

This is the stage-1 commit.  Stage-2 will occur after stage-1 has stabilized,
and will move cpu_critical*() into its own header file(s) + other things.
This commit may break non-i386 architectures in trivial ways.  This should
be temporary.

Reviewed by:	core
Approved by:	core

1 files changed, 9 insertions, 3 deletions

diff --git a/sys/i386/isa/npx.c b/sys/i386/isa/npx.c
index 43b012c..22a0282 100644
--- a/sys/i386/isa/npx.c
+++ b/sys/i386/isa/npx.c
@@ -429,9 +429,15 @@ no_irq13:
 	 * XXX hack around brokenness of bus_teardown_intr().  If we left the
 	 * irq active then we would get it instead of exception 16.
 	 */
-	mtx_lock_spin(&icu_lock);
-	INTRDIS(1 << irq_num);
-	mtx_unlock_spin(&icu_lock);
+	{
+		register_t crit;
+
+		crit = intr_disable();
+		mtx_lock_spin(&icu_lock);
+		INTRDIS(1 << irq_num);
+		mtx_unlock_spin(&icu_lock);
+		intr_restore(crit);
+	}
 
 	bus_release_resource(dev, SYS_RES_IRQ, irq_rid, irq_res);
 	bus_release_resource(dev, SYS_RES_IOPORT, ioport_rid, ioport_res);