[src/trunk]: src/sys/dev/ic com(4): Comment on lock order.

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

details:   https://anonhg.NetBSD.org/src/rev/8c8f2ad823df
branches:  trunk
changeset: 371721:8c8f2ad823df
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Mon Oct 03 19:57:41 2022 +0000

description:
com(4): Comment on lock order.

diffstat:

 sys/dev/ic/com.c |  8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diffs (25 lines):

diff -r 4b62851d96dc -r 8c8f2ad823df sys/dev/ic/com.c
--- a/sys/dev/ic/com.c  Mon Oct 03 19:57:25 2022 +0000
+++ b/sys/dev/ic/com.c  Mon Oct 03 19:57:41 2022 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: com.c,v 1.374 2022/10/03 19:26:35 riastradh Exp $ */
+/* $NetBSD: com.c,v 1.375 2022/10/03 19:57:41 riastradh Exp $ */
 
 /*-
  * Copyright (c) 1998, 1999, 2004, 2008 The NetBSD Foundation, Inc.
@@ -63,10 +63,14 @@
 /*
  * COM driver, uses National Semiconductor NS16450/NS16550AF UART
  * Supports automatic hardware flow control on StarTech ST16C650A UART
+ *
+ * Lock order:
+ *     tty_lock (IPL_VM)
+ *     -> sc->sc_lock (IPL_HIGH)
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: com.c,v 1.374 2022/10/03 19:26:35 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: com.c,v 1.375 2022/10/03 19:57:41 riastradh Exp $");
 
 #include "opt_com.h"
 #include "opt_ddb.h"