src: clarify

[Repository Conversion <srcmastr%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/272309801b80
branches:  trunk
changeset: 318199:272309801b80
user:      maxv <maxv%NetBSD.org@localhost>
date:      Sun Apr 15 17:26:39 2018 +0000
description:
clarify

diffstat:

 sys/sys/mbuf.h |  23 ++++++++++++-----------
 1 files changed, 12 insertions(+), 11 deletions(-)

diffs (61 lines):

diff -r 7ea839b1b5af -r 272309801b80 sys/sys/mbuf.h
--- a/sys/sys/mbuf.h    Sun Apr 15 17:22:03 2018 +0000
+++ b/sys/sys/mbuf.h    Sun Apr 15 17:26:39 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: mbuf.h,v 1.186 2018/04/15 07:35:49 maxv Exp $  */
+/*     $NetBSD: mbuf.h,v 1.187 2018/04/15 17:26:39 maxv Exp $  */
 
 /*
  * Copyright (c) 1996, 1997, 1999, 2001, 2007 The NetBSD Foundation, Inc.
@@ -254,7 +254,9 @@
 #define        M_EXT_MAXPAGES          ((65536 / MIN_PAGE_SIZE) + 1)
 #endif
 
-/* description of external storage mapped into mbuf, valid if M_EXT set */
+/*
+ * Description of external storage mapped into mbuf, valid if M_EXT set.
+ */
 struct _m_ext_storage {
        unsigned int ext_refcnt;
        int ext_flags;
@@ -263,19 +265,18 @@
                (struct mbuf *, void *, size_t, void *);
        void *ext_arg;                  /* argument for ext_free */
        size_t ext_size;                /* size of buffer, for ext_free */
+
        union {
-               paddr_t extun_paddr;    /* physical address (M_EXT_CLUSTER) */
-                                       /* pages (M_EXT_PAGES) */
-       /*
-        * XXX This is gross, but it doesn't really matter; this is
-        * XXX overlaid on top of the mbuf data area.
-        */
+               /* M_EXT_CLUSTER: physical address */
+               paddr_t extun_paddr;
 #ifdef M_EXT_MAXPAGES
+               /* M_EXT_PAGES: pages */
                struct vm_page *extun_pgs[M_EXT_MAXPAGES];
 #endif
        } ext_un;
 #define        ext_paddr       ext_un.extun_paddr
 #define        ext_pgs         ext_un.extun_pgs
+
 #ifdef DEBUG
        const char *ext_ofile;
        const char *ext_nfile;
@@ -297,12 +298,12 @@
  */
 #define        MBUF_DEFINE(name, mhlen, mlen)                                  \
        struct name {                                                   \
-               struct  m_hdr m_hdr;                                    \
+               struct m_hdr m_hdr;                                     \
                union {                                                 \
                        struct {                                        \
-                               struct  pkthdr MH_pkthdr;               \
+                               struct pkthdr MH_pkthdr;                \
                                union {                                 \
-                                       struct  _m_ext MH_ext;          \
+                                       struct _m_ext MH_ext;           \
                                        char MH_databuf[(mhlen)];       \
                                } MH_dat;                               \
                        } MH;                                           \