[src/trunk]: src/share/man/man9 Point out that spurious wake-ups are possible...

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

details:   https://anonhg.NetBSD.org/src/rev/d5574403a165
branches:  trunk
changeset: 1005541:d5574403a165
user:      pgoyette <pgoyette%NetBSD.org@localhost>
date:      Thu Dec 12 02:34:55 2019 +0000

description:
Point out that spurious wake-ups are possible, and that an LWP should
check for resource availability after being awoken.

diffstat:

 share/man/man9/condvar.9 |  11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diffs (32 lines):

diff -r 110619eb7101 -r d5574403a165 share/man/man9/condvar.9
--- a/share/man/man9/condvar.9  Thu Dec 12 02:15:42 2019 +0000
+++ b/share/man/man9/condvar.9  Thu Dec 12 02:34:55 2019 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: condvar.9,v 1.20 2019/04/12 11:02:22 abhinav Exp $
+.\"    $NetBSD: condvar.9,v 1.21 2019/12/12 02:34:55 pgoyette Exp $
 .\"
 .\" Copyright (c) 2006, 2007, 2008 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 12, 2017
+.Dd December 12, 2019
 .Dt CONDVAR 9
 .Os
 .Sh NAME
@@ -144,6 +144,13 @@
 .Pp
 Non-interruptable waits have the potential to deadlock the system, and so must
 be kept short (typically, under one second).
+.Pp
+Upon being awakened, the calling LWP should verify the availability
+of the resource (or other condition).
+It should not blindly assume that the resource is now available.
+If the resource is still not available, the calling LWP may call
+.Fn cv_wait
+again to continue waiting.
 .It Fn cv_wait_sig "cv" "mtx"
 .Pp
 As per