[src/trunk]: src/sys/netipsec Clarify, remove superfluous things.

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

details:   https://anonhg.NetBSD.org/src/rev/ea6eb9b6da6b
branches:  trunk
changeset: 832877:ea6eb9b6da6b
user:      maxv <maxv%NetBSD.org@localhost>
date:      Thu May 31 15:34:25 2018 +0000

description:
Clarify, remove superfluous things.

diffstat:

 sys/netipsec/ipsec_mbuf.c |  40 +++++++++++-----------------------------
 1 files changed, 11 insertions(+), 29 deletions(-)

diffs (99 lines):

diff -r bd089f3b00c2 -r ea6eb9b6da6b sys/netipsec/ipsec_mbuf.c
--- a/sys/netipsec/ipsec_mbuf.c Thu May 31 15:06:45 2018 +0000
+++ b/sys/netipsec/ipsec_mbuf.c Thu May 31 15:34:25 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ipsec_mbuf.c,v 1.27 2018/04/28 14:39:34 maxv Exp $     */
+/*     $NetBSD: ipsec_mbuf.c,v 1.28 2018/05/31 15:34:25 maxv Exp $     */
 
 /*
  * Copyright (c) 2002, 2003 Sam Leffler, Errno Consulting
@@ -29,7 +29,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ipsec_mbuf.c,v 1.27 2018/04/28 14:39:34 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ipsec_mbuf.c,v 1.28 2018/05/31 15:34:25 maxv Exp $");
 
 /*
  * IPsec-specific mbuf routines.
@@ -65,25 +65,15 @@
        for (m = m0; m != NULL; m = mprev->m_next) {
                /*
                 * Regular mbufs are ignored unless there's a cluster
-                * in front of it that we can use to coalesce.  We do
-                * the latter mainly so later clusters can be coalesced
-                * also w/o having to handle them specially (i.e. convert
-                * mbuf+cluster -> cluster).  This optimization is heavily
-                * influenced by the assumption that we're running over
-                * Ethernet where MCLBYTES is large enough that the max
-                * packet size will permit lots of coalescing into a
-                * single cluster.  This in turn permits efficient
-                * crypto operations, especially when using hardware.
+                * in front of it that we can use to coalesce.
                 */
                if ((m->m_flags & M_EXT) == 0) {
                        if (mprev && (mprev->m_flags & M_EXT) &&
                            m->m_len <= M_TRAILINGSPACE(mprev)) {
-                               /* XXX: this ignores mbuf types */
                                memcpy(mtod(mprev, char *) + mprev->m_len,
-                                      mtod(m, char *), m->m_len);
+                                   mtod(m, char *), m->m_len);
                                mprev->m_len += m->m_len;
-                               mprev->m_next = m->m_next;      /* unlink from chain */
-                               m_free(m);                      /* reclaim mbuf */
+                               mprev->m_next = m_free(m);
                                IPSEC_STATINC(IPSEC_STAT_MBCOALESCED);
                        } else {
                                mprev = m;
@@ -92,7 +82,7 @@
                }
 
                /*
-                * Writable mbufs are left alone (for now).
+                * Writable mbufs are left alone.
                 */
                if (!M_READONLY(m)) {
                        mprev = m;
@@ -105,16 +95,14 @@
                 * it anyway, we try to reduce the number of mbufs and
                 * clusters so that future work is easier).
                 */
-               KASSERTMSG(m->m_flags & M_EXT, "m_flags 0x%x", m->m_flags);
-               /* NB: we only coalesce into a cluster or larger */
+
+               /* We only coalesce into a cluster. */
                if (mprev != NULL && (mprev->m_flags & M_EXT) &&
                    m->m_len <= M_TRAILINGSPACE(mprev)) {
-                       /* XXX: this ignores mbuf types */
                        memcpy(mtod(mprev, char *) + mprev->m_len,
-                              mtod(m, char *), m->m_len);
+                           mtod(m, char *), m->m_len);
                        mprev->m_len += m->m_len;
-                       mprev->m_next = m->m_next;      /* unlink from chain */
-                       m_free(m);                      /* reclaim mbuf */
+                       mprev->m_next = m_free(m);
                        IPSEC_STATINC(IPSEC_STAT_CLCOALESCED);
                        continue;
                }
@@ -123,12 +111,6 @@
                 * Allocate new space to hold the copy...
                 */
                if (mprev == NULL && (m->m_flags & M_PKTHDR)) {
-                       /*
-                        * NB: if a packet header is present we must
-                        * allocate the mbuf separately from any cluster
-                        * because M_MOVE_PKTHDR will smash the data
-                        * pointer and drop the M_EXT marker.
-                        */
                        MGETHDR(n, M_DONTWAIT, m->m_type);
                        if (n == NULL) {
                                m_freem(m0);
@@ -162,7 +144,7 @@
                mfirst = n;
                mlast = NULL;
                for (;;) {
-                       int cc = min(len, MCLBYTES);
+                       const int cc = min(len, MCLBYTES);
                        memcpy(mtod(n, char *), mtod(m, char *) + off, cc);
                        n->m_len = cc;
                        if (mlast != NULL)