On Sun, Aug 14, 2022 at 02:04:09AM +0300, Vitaliy Makkoveev wrote:
> On Sat, Aug 13, 2022 at 09:08:36PM +0200, Alexander Bluhm wrote:
> > Hi,
> >
> > While running forwarding in parallel, I have introduced a hard
> > barrier for parallel local protocol processing. The packets are
> > requeued from shared to exclusive netlock.
> >
> > Unless we unlock all protocol input routines at once, we need some
> > mechanism from to move from one queue to the other. The problem
> > is, that we have to remember next protocol field and offset of the
> > parsed header chain.
> >
> > A simple example is IPv6 hop-by-hop options precessing. This code
> > is MP safe and can be moved from ip6_local() to ip6_ours() to run
> > in parallel. If there were any options, the offset and next protocol
> > are stored in a mbuf tag. Without tag we know that it is a regular
> > IPv6 header.
> >
> > Of course mbuf tags kill performance, but who uses hop-by-hop options
> > anyway? pf drops such packets per default.
> >
> > ok?
> >
>
> Isn't it better to use ip6_offnxt?
Maybe I want to use the same trick for the IP deliver loop one day.
But until that happens ip6_offnxt is consistent to PACKET_TAG_IP6_OFFNXT.
bluhm
Index: netinet/ip_input.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet/ip_input.c,v
retrieving revision 1.378
diff -u -p -r1.378 ip_input.c
--- netinet/ip_input.c 12 Aug 2022 14:49:15 -0000 1.378
+++ netinet/ip_input.c 15 Aug 2022 09:38:53 -0000
@@ -560,11 +560,13 @@ ip_input_if(struct mbuf **mp, int *offp,
int
ip_local(struct mbuf **mp, int *offp, int nxt, int af)
{
- struct ip *ip;
+ if (*offp == 0) {
+ struct ip *ip;
- ip = mtod(*mp, struct ip *);
- *offp = ip->ip_hl << 2;
- nxt = ip->ip_p;
+ ip = mtod(*mp, struct ip *);
+ *offp = ip->ip_hl << 2;
+ nxt = ip->ip_p;
+ }
/* Check whether we are already in a IPv4/IPv6 local deliver loop. */
if (af == AF_UNSPEC)
Index: netinet6/ip6_input.c
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/netinet6/ip6_input.c,v
retrieving revision 1.252
diff -u -p -r1.252 ip6_input.c
--- netinet6/ip6_input.c 12 Aug 2022 14:49:15 -0000 1.252
+++ netinet6/ip6_input.c 15 Aug 2022 09:43:20 -0000
@@ -167,6 +167,11 @@ ip6_init(void)
#endif
}
+struct ip6_offnxt {
+ int ion_off;
+ int ion_nxt;
+};
+
/*
* Enqueue packet for local delivery. Queuing is used as a boundary
* between the network layer (input/forward path) running with
@@ -175,10 +180,37 @@ ip6_init(void)
int
ip6_ours(struct mbuf **mp, int *offp, int nxt, int af)
{
+ /* ip6_hbhchcheck() may be run before, then off and nxt are set */
+ if (*offp == 0) {
+ nxt = ip6_hbhchcheck(mp, offp, NULL);
+ if (nxt == IPPROTO_DONE)
+ return IPPROTO_DONE;
+ }
+
/* We are already in a IPv4/IPv6 local deliver loop. */
if (af != AF_UNSPEC)
return ip6_local(mp, offp, nxt, af);
+ /* save values for later, use after dequeue */
+ if (*offp != sizeof(struct ip6_hdr)) {
+ struct m_tag *mtag;
+ struct ip6_offnxt *ion;
+
+ /* mbuf tags are expensive, but only used for header options */
+ mtag = m_tag_get(PACKET_TAG_IP6_OFFNXT, sizeof(*ion),
+ M_NOWAIT);
+ if (mtag == NULL) {
+ ip6stat_inc(ip6s_idropped);
+ m_freemp(mp);
+ return IPPROTO_DONE;
+ }
+ ion = (struct ip6_offnxt *)(mtag + 1);
+ ion->ion_off = *offp;
+ ion->ion_nxt = nxt;
+
+ m_tag_prepend(*mp, mtag);
+ }
+
niq_enqueue(&ip6intrq, *mp);
*mp = NULL;
return IPPROTO_DONE;
@@ -584,9 +616,27 @@ ip6_input_if(struct mbuf **mp, int *offp
int
ip6_local(struct mbuf **mp, int *offp, int nxt, int af)
{
- nxt = ip6_hbhchcheck(mp, offp, NULL);
- if (nxt == IPPROTO_DONE)
- return IPPROTO_DONE;
+ if (*offp == 0) {
+ struct m_tag *mtag;
+
+ mtag = m_tag_find(*mp, PACKET_TAG_IP6_OFFNXT, NULL);
+ if (mtag != NULL) {
+ struct ip6_offnxt *ion;
+
+ ion = (struct ip6_offnxt *)(mtag + 1);
+ *offp = ion->ion_off;
+ nxt = ion->ion_nxt;
+
+ m_tag_delete(*mp, mtag);
+ } else {
+ struct ip6_hdr *ip6;
+
+ ip6 = mtod(*mp, struct ip6_hdr *);
+ *offp = sizeof(struct ip6_hdr);
+ nxt = ip6->ip6_nxt;
+
+ }
+ }
/* Check whether we are already in a IPv4/IPv6 local deliver loop. */
if (af == AF_UNSPEC)
Index: sys/mbuf.h
===================================================================
RCS file: /data/mirror/openbsd/cvs/src/sys/sys/mbuf.h,v
retrieving revision 1.254
diff -u -p -r1.254 mbuf.h
--- sys/mbuf.h 14 Feb 2022 04:33:18 -0000 1.254
+++ sys/mbuf.h 15 Aug 2022 09:43:14 -0000
@@ -479,6 +479,7 @@ struct m_tag *m_tag_next(struct mbuf *,
#define PACKET_TAG_SRCROUTE 0x1000 /* IPv4 source routing options */
#define PACKET_TAG_TUNNEL 0x2000 /* Tunnel endpoint address */
#define PACKET_TAG_CARP_BAL_IP 0x4000 /* carp(4) ip balanced marker */
+#define PACKET_TAG_IP6_OFFNXT 0x8000 /* IPv6 offset and next proto */
#define MTAG_BITS \
("\20\1IPSEC_IN_DONE\2IPSEC_OUT_DONE\3IPSEC_FLOWINFO" \
