On Sat, 23 Feb 2002, Matthew Dillon wrote:

> :My version of it does less than this.  I only use it to help implement
> :spinlocks.
>
>     You put together infrastructure to deal with pending pci interrupts?
>     If so, then why not commit it (or at least commit a version #ifdef'd
>     for the i386 architecture).

It's too messy and unfinished (doesn't work right for SMP or irqs >= 16),
and dificult to untangle from my other patches.  I posted these partial
ones to attempt to inhibit() recomplication of the current critical*
functions in directions that I don't want to go :-).

> :Index: kern_switch.c
> :===================================================================
> :RCS file: /home/ncvs/src/sys/kern/kern_switch.c,v
> :retrieving revision 1.20
> :diff -u -2 -r1.20 kern_switch.c
> :--- kern_switch.c    11 Feb 2002 20:37:51 -0000      1.20
> :+++ kern_switch.c    13 Feb 2002 05:34:20 -0000
> :@@ -70,14 +70,21 @@
> : }
> :
> :-/* Critical sections that prevent preemption. */
> :+/*-
> :+ * Critical section handling.
> :+ * XXX doesn't belong here.
> :+ *
> :+ * Entering a critical section only blocks non-fast interrupts.
> :+ * critical_enter() is similar to splhigh() in a 2-level spl setup under
> :+ * old versions of FreeBSD.
> :+ *
> :+ * Exiting from all critical sections unblocks non-fast interrupts and runs
> :+ * the handlers of any that were blocked.  critical_exit() is similar to
> :+ * spl(old_level) in a 2-level spl setup under old versions of FreeBSD.
> :+ */
> : void
> : critical_enter(void)
> : {
> :-    struct thread *td;
> :
> :-    td = curthread;
> :-    if (td->td_critnest == 0)
> :-            td->td_savecrit = cpu_critical_enter();
> :-    td->td_critnest++;
> :+    curthread->td_critnest++;
> : }
> :
> :@@ -85,12 +92,7 @@
> : critical_exit(void)
> : {
> :-    struct thread *td;
> :
> :-    td = curthread;
> :-    if (td->td_critnest == 1) {
> :-            td->td_critnest = 0;
> :-            cpu_critical_exit(td->td_savecrit);
> :-    } else
> :-            td->td_critnest--;
> :+    if (--curthread->td_critnest == 0 && (ipending | spending) != 0)
> :+            unpend();
> : }

ipending here works much as in RELENG_4.  It is ORed into by sched_ithd()
if curthread->td_critnest != 0.  Nothing special is needed for pci
(the ICU masks pending interrupts).

Bruce


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