[src/trunk]: src/share/man/man9 kpreempt(9): add a note when kernel preemptio...

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

details:   https://anonhg.NetBSD.org/src/rev/c5bd9271cb86
branches:  trunk
changeset: 752136:c5bd9271cb86
user:      rmind <rmind%NetBSD.org@localhost>
date:      Tue Feb 16 19:21:30 2010 +0000

description:
kpreempt(9): add a note when kernel preemption is disabled/deferred.
Sprinkle cross-links, bump dates.

diffstat:

 share/man/man9/kpreempt.9 |  14 +++++++++++---
 share/man/man9/mutex.9    |   5 +++--
 share/man/man9/spl.9      |   5 +++--
 3 files changed, 17 insertions(+), 7 deletions(-)

diffs (97 lines):

diff -r a2ed5b77675c -r c5bd9271cb86 share/man/man9/kpreempt.9
--- a/share/man/man9/kpreempt.9 Tue Feb 16 18:57:53 2010 +0000
+++ b/share/man/man9/kpreempt.9 Tue Feb 16 19:21:30 2010 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: kpreempt.9,v 1.2 2008/12/21 10:32:56 ad Exp $
+.\"    $NetBSD: kpreempt.9,v 1.3 2010/02/16 19:21:30 rmind Exp $
 .\"
 .\" Copyright (c)2008 YAMAMOTO Takashi,
 .\" All rights reserved.
@@ -25,7 +25,7 @@
 .\" SUCH DAMAGE.
 .\"
 .\" ------------------------------------------------------------
-.Dd December 21, 2008
+.Dd February 16, 2010
 .Dt KPREEMPT 9
 .Os
 .\" ------------------------------------------------------------
@@ -52,6 +52,13 @@
 On architectures where kernel preemption is not supported natively, these
 functions may still be used.
 .Pp
+It should be noted that kernel preemption is also disabled when holding
+the interrupt priority level above IPL_NONE, e.g. using
+.Xr spl 9
+or spinning
+.Xr mutex 9
+calls or holding kernel_lock (indicating that the code is not MT safe).
+.Pp
 .Fn kpreempt_disable
 disables kernel preemption of the calling LWP.
 Note that disabling kernel preemption can prevent LWPs with higher priorities
@@ -70,10 +77,11 @@
 returns
 .Dv true
 if preemption of the calling LWP is disabled.
-It's for diagnostic purpose.
+It is only for diagnostic purpose.
 .\" ------------------------------------------------------------
 .\" .Sh RETURN VALUES
 .\" ------------------------------------------------------------
 .Sh SEE ALSO
 .Xr intro 9 ,
+.Xr mutex 9 ,
 .Xr spl 9
diff -r a2ed5b77675c -r c5bd9271cb86 share/man/man9/mutex.9
--- a/share/man/man9/mutex.9    Tue Feb 16 18:57:53 2010 +0000
+++ b/share/man/man9/mutex.9    Tue Feb 16 19:21:30 2010 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: mutex.9,v 1.21 2010/01/25 17:27:41 jruoho Exp $
+.\"    $NetBSD: mutex.9,v 1.22 2010/02/16 19:21:30 rmind Exp $
 .\"
 .\" Copyright (c) 2007, 2009 The NetBSD Foundation, Inc.
 .\" All rights reserved.
@@ -27,7 +27,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd November 22, 2009
+.Dd February 16, 2010
 .Dt MUTEX 9
 .Os
 .Sh NAME
@@ -251,6 +251,7 @@
 .Xr membar_ops 3 ,
 .Xr lockstat 8 ,
 .Xr condvar 9 ,
+.Xr kpreempt 9 ,
 .Xr rwlock 9 ,
 .Xr spl 9
 .Pp
diff -r a2ed5b77675c -r c5bd9271cb86 share/man/man9/spl.9
--- a/share/man/man9/spl.9      Tue Feb 16 18:57:53 2010 +0000
+++ b/share/man/man9/spl.9      Tue Feb 16 19:21:30 2010 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: spl.9,v 1.38 2010/02/07 10:49:35 wiz Exp $
+.\"    $NetBSD: spl.9,v 1.39 2010/02/16 19:21:30 rmind Exp $
 .\"
 .\" Copyright (c) 2000, 2001 Jason R. Thorpe.  All rights reserved.
 .\" Copyright (c) 1997 Michael Long.
@@ -27,7 +27,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd February 6, 2010
+.Dd February 16, 2010
 .Dt SPL 9
 .Os
 .Sh NAME
@@ -210,6 +210,7 @@
 .Sh SEE ALSO
 .Xr condvar 9 ,
 .Xr i386/splraise 9 ,
+.Xr kpreempt 9 ,
 .Xr mutex 9 ,
 .Xr rwlock 9
 .Sh HISTORY