[src/rmind-uvmplock]: src/sys/arch/x86/x86 pmap_deactivate: improve comment.

[rmind <rmind%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/67bc532440b1
branches:  rmind-uvmplock
changeset: 753074:67bc532440b1
user:      rmind <rmind%NetBSD.org@localhost>
date:      Tue Mar 08 23:26:35 2011 +0000

description:
pmap_deactivate: improve comment.

diffstat:

 sys/arch/x86/x86/pmap.c |  17 ++++++++---------
 1 files changed, 8 insertions(+), 9 deletions(-)

diffs (47 lines):

diff -r 3278c1cd16aa -r 67bc532440b1 sys/arch/x86/x86/pmap.c
--- a/sys/arch/x86/x86/pmap.c   Tue Mar 08 20:07:30 2011 +0000
+++ b/sys/arch/x86/x86/pmap.c   Tue Mar 08 23:26:35 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pmap.c,v 1.105.2.11 2011/03/08 20:07:30 rmind Exp $    */
+/*     $NetBSD: pmap.c,v 1.105.2.12 2011/03/08 23:26:35 rmind Exp $    */
 
 /*-
  * Copyright (c) 2008, 2010 The NetBSD Foundation, Inc.
@@ -171,7 +171,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.105.2.11 2011/03/08 20:07:30 rmind Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.105.2.12 2011/03/08 23:26:35 rmind Exp $");
 
 #include "opt_user_ldt.h"
 #include "opt_lockdebug.h"
@@ -2712,11 +2712,10 @@
 }
 
 /*
- * pmap_deactivate: deactivate a process' pmap
+ * pmap_deactivate: deactivate a process' pmap.
  *
- * => must be called with kernel preemption disabled (high SPL is enough)
+ * => Must be called with kernel preemption disabled (high IPL is enough).
  */
-
 void
 pmap_deactivate(struct lwp *l)
 {
@@ -2730,10 +2729,10 @@
        }
 
        /*
-        * wait for pending TLB shootdowns to complete.  necessary
-        * because TLB shootdown state is per-CPU, and the LWP may
-        * be coming off the CPU before it has a chance to call
-        * pmap_update().
+        * Wait for pending TLB shootdowns to complete.  Necessary because
+        * TLB shootdown state is per-CPU, and the LWP may be coming off
+        * the CPU before it has a chance to call pmap_update(), e.g. due
+        * to kernel preemption or blocking routine in between.
         */
        pmap_tlb_shootnow();