[src/trunk]: src/share/man/man9 rnd(9): Note that rndsource callbacks are nev...

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

details:   https://anonhg.NetBSD.org/src/rev/cdfb72b88a14
branches:  trunk
changeset: 366173:cdfb72b88a14
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Tue May 17 01:39:57 2022 +0000

description:
rnd(9): Note that rndsource callbacks are never run in hardint.

But they may be run in softint at IPL_SOFTSERIAL.

diffstat:

 share/man/man9/rnd.9 |  13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)

diffs (27 lines):

diff -r 88ecf5e9510f -r cdfb72b88a14 share/man/man9/rnd.9
--- a/share/man/man9/rnd.9      Tue May 17 01:22:14 2022 +0000
+++ b/share/man/man9/rnd.9      Tue May 17 01:39:57 2022 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: rnd.9,v 1.30 2022/03/19 11:54:53 riastradh Exp $
+.\"    $NetBSD: rnd.9,v 1.31 2022/05/17 01:39:57 riastradh Exp $
 .\"
 .\" Copyright (c) 1997 The NetBSD Foundation, Inc.
 .\" All rights reserved.
@@ -171,6 +171,17 @@
 .Fa callback
 in serial \(em it never issues two calls to the same source's callback
 at the same time in two differen threads or on two different CPUs.
+.Pp
+The callback may be invoked in thread context or soft interrupt
+context, up to
+.Dv SOFTINT_SERIAL ,
+and as such must follow the rules of soft interrupt handlers in
+.Xr softint 9
+\(em that is, the callback must never sleep, except on adaptive
+.Xr mutex 9
+locks at
+.Dv IPL_SOFTSERIAL .
+The callback will never be called in hard interrupt context.
 .It Fn rnd_attach_source "rnd_source" "devname" "type" "flags"
 Makes
 .Fa rnd_source