[NETFILTER]: reduce netfilter sk_buff enlargement
Harald Welte [Wed, 10 Aug 2005 02:24:19 +0000 (19:24 -0700)]
As discussed at netconf'05, we're trying to save every bit in sk_buff.
The patch below makes sk_buff 8 bytes smaller.  I did some basic
testing on my notebook and it seems to work.

The only real in-tree user of nfcache was IPVS, who only needs a
single bit.  Unfortunately I couldn't find some other free bit in
sk_buff to stuff that bit into, so I introduced a separate field for
them.  Maybe the IPVS guys can resolve that to further save space.

Initially I wanted to shrink pkt_type to three bits (PACKET_HOST and
alike are only 6 values defined), but unfortunately the bluetooth code
overloads pkt_type :(

The conntrack-event-api (out-of-tree) uses nfcache, but Rusty just
came up with a way how to do it without any skb fields, so it's safe
to remove it.

- remove all never-implemented 'nfcache' code
- don't have ipvs code abuse 'nfcache' field. currently get's their own
  compile-conditional skb->ipvs_property field.  IPVS maintainers can
  decide to move this bit elswhere, but nfcache needs to die.
- remove skb->nfcache field to save 4 bytes
- move skb->nfctinfo into three unused bits to save further 4 bytes

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

27 files changed:
include/linux/netfilter.h
include/linux/netfilter_decnet.h
include/linux/netfilter_ipv4.h
include/linux/netfilter_ipv6.h
include/linux/skbuff.h
net/bridge/netfilter/ebt_mark.c
net/core/skbuff.c
net/ipv4/ip_output.c
net/ipv4/ipvs/ip_vs_core.c
net/ipv4/ipvs/ip_vs_xmit.c
net/ipv4/netfilter/ip_conntrack_core.c
net/ipv4/netfilter/ip_nat_core.c
net/ipv4/netfilter/ip_nat_standalone.c
net/ipv4/netfilter/ip_queue.c
net/ipv4/netfilter/ip_tables.c
net/ipv4/netfilter/ipt_CLASSIFY.c
net/ipv4/netfilter/ipt_CONNMARK.c
net/ipv4/netfilter/ipt_DSCP.c
net/ipv4/netfilter/ipt_ECN.c
net/ipv4/netfilter/ipt_MARK.c
net/ipv4/netfilter/ipt_REJECT.c
net/ipv4/netfilter/ipt_TCPMSS.c
net/ipv4/netfilter/ipt_TOS.c
net/ipv6/ip6_output.c
net/ipv6/netfilter/ip6_queue.c
net/ipv6/netfilter/ip6_tables.c
net/ipv6/netfilter/ip6t_MARK.c

index 2e20454..ec60856 100644 (file)
 #define NF_STOP 5
 #define NF_MAX_VERDICT NF_STOP
 
+/* only for userspace compatibility */
+#ifndef __KERNEL__
 /* Generic cache responses from hook functions.
    <= 0x2000 is used for protocol-flags. */
 #define NFC_UNKNOWN 0x4000
 #define NFC_ALTERED 0x8000
+#endif
 
 #ifdef __KERNEL__
 #include <linux/config.h>
index 3064eec..0189794 100644 (file)
@@ -9,6 +9,8 @@
 
 #include <linux/netfilter.h>
 
+/* only for userspace compatibility */
+#ifndef __KERNEL__
 /* IP Cache bits. */
 /* Src IP address. */
 #define NFC_DN_SRC             0x0001
@@ -18,6 +20,7 @@
 #define NFC_DN_IF_IN           0x0004
 /* Output device. */
 #define NFC_DN_IF_OUT          0x0008
+#endif /* ! __KERNEL__ */
 
 /* DECnet Hooks */
 /* After promisc drops, checksum checks. */
index 3ebc36a..552815b 100644 (file)
@@ -8,6 +8,8 @@
 #include <linux/config.h>
 #include <linux/netfilter.h>
 
+/* only for userspace compatibility */
+#ifndef __KERNEL__
 /* IP Cache bits. */
 /* Src IP address. */
 #define NFC_IP_SRC             0x0001
@@ -35,6 +37,7 @@
 #define NFC_IP_DST_PT          0x0400
 /* Something else about the proto */
 #define NFC_IP_PROTO_UNKNOWN   0x2000
+#endif /* ! __KERNEL__ */
 
 /* IP Hooks */
 /* After promisc drops, checksum checks. */
index bee7a5e..20c069a 100644 (file)
@@ -10,6 +10,8 @@
 
 #include <linux/netfilter.h>
 
+/* only for userspace compatibility */
+#ifndef __KERNEL__
 /* IP Cache bits. */
 /* Src IP address. */
 #define NFC_IP6_SRC              0x0001
@@ -38,6 +40,7 @@
 #define NFC_IP6_DST_PT           0x0400
 /* Something else about the proto */
 #define NFC_IP6_PROTO_UNKNOWN    0x2000
+#endif /* ! __KERNEL__ */
 
 
 /* IP6 Hooks */
index 2e40f4c..4b929c3 100644 (file)
@@ -190,7 +190,6 @@ struct skb_shared_info {
  *     @end: End pointer
  *     @destructor: Destruct function
  *     @nfmark: Can be used for communication between hooks
- *     @nfcache: Cache info
  *     @nfct: Associated connection, if any
  *     @nfctinfo: Relationship of this skb to the connection
  *     @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
@@ -252,17 +251,18 @@ struct sk_buff {
        __u8                    local_df:1,
                                cloned:1,
                                ip_summed:2,
-                               nohdr:1;
-                               /* 3 bits spare */
+                               nohdr:1,
+                               nfctinfo:3;
        __u8                    pkt_type;
        __be16                  protocol;
 
        void                    (*destructor)(struct sk_buff *skb);
 #ifdef CONFIG_NETFILTER
        __u32                   nfmark;
-       __u32                   nfcache;
-       __u32                   nfctinfo;
        struct nf_conntrack     *nfct;
+#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
+       __u8                    ipvs_property:1;
+#endif
 #ifdef CONFIG_BRIDGE_NETFILTER
        struct nf_bridge_info   *nf_bridge;
 #endif
index 02c632b..c93d35a 100644 (file)
@@ -23,10 +23,9 @@ static int ebt_target_mark(struct sk_buff **pskb, unsigned int hooknr,
 {
        struct ebt_mark_t_info *info = (struct ebt_mark_t_info *)data;
 
-       if ((*pskb)->nfmark != info->mark) {
+       if ((*pskb)->nfmark != info->mark)
                (*pskb)->nfmark = info->mark;
-               (*pskb)->nfcache |= NFC_ALTERED;
-       }
+
        return info->target;
 }
 
index 7eab867..096991c 100644 (file)
@@ -361,7 +361,6 @@ struct sk_buff *skb_clone(struct sk_buff *skb, unsigned int __nocast gfp_mask)
        n->destructor = NULL;
 #ifdef CONFIG_NETFILTER
        C(nfmark);
-       C(nfcache);
        C(nfct);
        nf_conntrack_get(skb->nfct);
        C(nfctinfo);
@@ -424,7 +423,6 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
        new->destructor = NULL;
 #ifdef CONFIG_NETFILTER
        new->nfmark     = old->nfmark;
-       new->nfcache    = old->nfcache;
        new->nfct       = old->nfct;
        nf_conntrack_get(old->nfct);
        new->nfctinfo   = old->nfctinfo;
index 80d1310..766564c 100644 (file)
@@ -392,7 +392,6 @@ static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from)
 #endif
 #ifdef CONFIG_NETFILTER
        to->nfmark = from->nfmark;
-       to->nfcache = from->nfcache;
        /* Connection association is same as pre-frag packet */
        nf_conntrack_put(to->nfct);
        to->nfct = from->nfct;
index 5fb257d..3ac7eec 100644 (file)
@@ -22,6 +22,7 @@
  *
  * Changes:
  *     Paul `Rusty' Russell            properly handle non-linear skbs
+ *     Harald Welte                    don't use nfcache
  *
  */
 
@@ -529,7 +530,7 @@ static unsigned int ip_vs_post_routing(unsigned int hooknum,
                                       const struct net_device *out,
                                       int (*okfn)(struct sk_buff *))
 {
-       if (!((*pskb)->nfcache & NFC_IPVS_PROPERTY))
+       if (!((*pskb)->ipvs_property))
                return NF_ACCEPT;
 
        /* The packet was sent from IPVS, exit this chain */
@@ -701,7 +702,7 @@ static int ip_vs_out_icmp(struct sk_buff **pskb, int *related)
        /* do the statistics and put it back */
        ip_vs_out_stats(cp, skb);
 
-       skb->nfcache |= NFC_IPVS_PROPERTY;
+       skb->ipvs_property = 1;
        verdict = NF_ACCEPT;
 
   out:
@@ -739,7 +740,7 @@ ip_vs_out(unsigned int hooknum, struct sk_buff **pskb,
 
        EnterFunction(11);
 
-       if (skb->nfcache & NFC_IPVS_PROPERTY)
+       if (skb->ipvs_property)
                return NF_ACCEPT;
 
        iph = skb->nh.iph;
@@ -821,7 +822,7 @@ ip_vs_out(unsigned int hooknum, struct sk_buff **pskb,
        ip_vs_set_state(cp, IP_VS_DIR_OUTPUT, skb, pp);
        ip_vs_conn_put(cp);
 
-       skb->nfcache |= NFC_IPVS_PROPERTY;
+       skb->ipvs_property = 1;
 
        LeaveFunction(11);
        return NF_ACCEPT;
index a8512a3..3b87482 100644 (file)
@@ -127,7 +127,7 @@ ip_vs_dst_reset(struct ip_vs_dest *dest)
 
 #define IP_VS_XMIT(skb, rt)                            \
 do {                                                   \
-       (skb)->nfcache |= NFC_IPVS_PROPERTY;            \
+       (skb)->ipvs_property = 1;                       \
        (skb)->ip_summed = CHECKSUM_NONE;               \
        NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, (skb), NULL,  \
                (rt)->u.dst.dev, dst_output);           \
index a7f0c82..04c3414 100644 (file)
@@ -625,9 +625,6 @@ unsigned int ip_conntrack_in(unsigned int hooknum,
                return NF_DROP;
        }
 
-       /* FIXME: Do this right please. --RR */
-       (*pskb)->nfcache |= NFC_UNKNOWN;
-
 /* Doesn't cover locally-generated broadcast, so not worth it. */
 #if 0
        /* Ignore broadcast: no `connection'. */
@@ -943,10 +940,8 @@ ip_ct_gather_frags(struct sk_buff *skb, u_int32_t user)
        skb = ip_defrag(skb, user);
        local_bh_enable();
 
-       if (skb) {
+       if (skb)
                ip_send_check(skb->nh.iph);
-               skb->nfcache |= NFC_ALTERED;
-       }
        return skb;
 }
 
index 739b6dd..ed4d731 100644 (file)
@@ -321,7 +321,6 @@ manip_pkt(u_int16_t proto,
 {
        struct iphdr *iph;
 
-       (*pskb)->nfcache |= NFC_ALTERED;
        if (!skb_ip_make_writable(pskb, iphdroff + sizeof(*iph)))
                return 0;
 
index 91d5ea1..9ecba97 100644 (file)
@@ -73,8 +73,6 @@ ip_nat_fn(unsigned int hooknum,
        IP_NF_ASSERT(!((*pskb)->nh.iph->frag_off
                       & htons(IP_MF|IP_OFFSET)));
 
-       (*pskb)->nfcache |= NFC_UNKNOWN;
-
        /* If we had a hardware checksum before, it's now invalid */
        if ((*pskb)->ip_summed == CHECKSUM_HW)
                if (skb_checksum_help(*pskb, (out == NULL)))
index c6baa81..bc0af8d 100644 (file)
@@ -392,7 +392,6 @@ ipq_mangle_ipv4(ipq_verdict_msg_t *v, struct ipq_queue_entry *e)
                return -ENOMEM;
        memcpy(e->skb->data, v->payload, v->data_len);
        e->skb->ip_summed = CHECKSUM_NONE;
-       e->skb->nfcache |= NFC_ALTERED;
 
        /*
         * Extra routing may needed on local out, as the QUEUE target never
index c88dfcd..ff8d85d 100644 (file)
@@ -312,7 +312,6 @@ ipt_do_table(struct sk_buff **pskb,
        do {
                IP_NF_ASSERT(e);
                IP_NF_ASSERT(back);
-               (*pskb)->nfcache |= e->nfcache;
                if (ip_packet_match(ip, indev, outdev, &e->ip, offset)) {
                        struct ipt_entry_target *t;
 
index 9842e6e..dab78d8 100644 (file)
@@ -32,10 +32,8 @@ target(struct sk_buff **pskb,
 {
        const struct ipt_classify_target_info *clinfo = targinfo;
 
-       if((*pskb)->priority != clinfo->priority) {
+       if((*pskb)->priority != clinfo->priority) 
                (*pskb)->priority = clinfo->priority;
-               (*pskb)->nfcache |= NFC_ALTERED;
-       }
 
        return IPT_CONTINUE;
 }
index 8ed7441..1346380 100644 (file)
@@ -61,10 +61,8 @@ target(struct sk_buff **pskb,
            case IPT_CONNMARK_RESTORE:
                nfmark = (*pskb)->nfmark;
                diff = (ct->mark ^ nfmark) & markinfo->mask;
-               if (diff != 0) {
+               if (diff != 0)
                    (*pskb)->nfmark = nfmark ^ diff;
-                   (*pskb)->nfcache |= NFC_ALTERED;
-               }
                break;
            }
        }
index 3ea4509..975476f 100644 (file)
@@ -51,7 +51,6 @@ target(struct sk_buff **pskb,
                                                 sizeof(diffs),
                                                 (*pskb)->nh.iph->check
                                                 ^ 0xFFFF));
-               (*pskb)->nfcache |= NFC_ALTERED;
        }
        return IPT_CONTINUE;
 }
index 94a0ce1..f63a9bc 100644 (file)
@@ -43,7 +43,6 @@ set_ect_ip(struct sk_buff **pskb, const struct ipt_ECN_info *einfo)
                                                 sizeof(diffs),
                                                 (*pskb)->nh.iph->check
                                                 ^0xFFFF));
-               (*pskb)->nfcache |= NFC_ALTERED;
        } 
        return 1;
 }
@@ -87,7 +86,6 @@ set_ect_tcp(struct sk_buff **pskb, const struct ipt_ECN_info *einfo, int inward)
                tcph->check = csum_fold(csum_partial((char *)diffs,
                                                     sizeof(diffs),
                                                     tcph->check^0xFFFF));
-       (*pskb)->nfcache |= NFC_ALTERED;
        return 1;
 }
 
index 8526398..52b4f2c 100644 (file)
@@ -29,10 +29,9 @@ target_v0(struct sk_buff **pskb,
 {
        const struct ipt_mark_target_info *markinfo = targinfo;
 
-       if((*pskb)->nfmark != markinfo->mark) {
+       if((*pskb)->nfmark != markinfo->mark)
                (*pskb)->nfmark = markinfo->mark;
-               (*pskb)->nfcache |= NFC_ALTERED;
-       }
+
        return IPT_CONTINUE;
 }
 
@@ -61,10 +60,9 @@ target_v1(struct sk_buff **pskb,
                break;
        }
 
-       if((*pskb)->nfmark != mark) {
+       if((*pskb)->nfmark != mark)
                (*pskb)->nfmark = mark;
-               (*pskb)->nfcache |= NFC_ALTERED;
-       }
+
        return IPT_CONTINUE;
 }
 
index 9156964..f115a84 100644 (file)
@@ -156,7 +156,6 @@ static void send_reset(struct sk_buff *oldskb, int hook)
 
        /* This packet will not be the same as the other: clear nf fields */
        nf_reset(nskb);
-       nskb->nfcache = 0;
        nskb->nfmark = 0;
 #ifdef CONFIG_BRIDGE_NETFILTER
        nf_bridge_put(nskb->nf_bridge);
index 7b84a25..9492883 100644 (file)
@@ -190,7 +190,6 @@ ipt_tcpmss_target(struct sk_buff **pskb,
               newmss);
 
  retmodified:
-       (*pskb)->nfcache |= NFC_UNKNOWN | NFC_ALTERED;
        return IPT_CONTINUE;
 }
 
index 85c70d2..49abb7e 100644 (file)
@@ -46,7 +46,6 @@ target(struct sk_buff **pskb,
                                                 sizeof(diffs),
                                                 (*pskb)->nh.iph->check
                                                 ^0xFFFF));
-               (*pskb)->nfcache |= NFC_ALTERED;
        }
        return IPT_CONTINUE;
 }
index ae652ca..590d2b7 100644 (file)
@@ -185,19 +185,6 @@ int ip6_route_me_harder(struct sk_buff *skb)
 }
 #endif
 
-static inline int ip6_maybe_reroute(struct sk_buff *skb)
-{
-#ifdef CONFIG_NETFILTER
-       if (skb->nfcache & NFC_ALTERED){
-               if (ip6_route_me_harder(skb) != 0){
-                       kfree_skb(skb);
-                       return -EINVAL;
-               }
-       }
-#endif /* CONFIG_NETFILTER */
-       return dst_output(skb);
-}
-
 /*
  *     xmit an sk_buff (used by TCP)
  */
@@ -266,7 +253,8 @@ int ip6_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
        mtu = dst_mtu(dst);
        if ((skb->len <= mtu) || ipfragok) {
                IP6_INC_STATS(IPSTATS_MIB_OUTREQUESTS);
-               return NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, skb, NULL, dst->dev, ip6_maybe_reroute);
+               return NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, skb, NULL, dst->dev,
+                               dst_output);
        }
 
        if (net_ratelimit())
index a16df5b..83ccedc 100644 (file)
@@ -388,7 +388,6 @@ ipq_mangle_ipv6(ipq_verdict_msg_t *v, struct ipq_queue_entry *e)
                return -ENOMEM;
        memcpy(e->skb->data, v->payload, v->data_len);
        e->skb->ip_summed = CHECKSUM_NONE;
-       e->skb->nfcache |= NFC_ALTERED;
 
        /*
         * Extra routing may needed on local out, as the QUEUE target never
index 7303451..41a67cf 100644 (file)
@@ -401,7 +401,6 @@ ip6t_do_table(struct sk_buff **pskb,
        do {
                IP_NF_ASSERT(e);
                IP_NF_ASSERT(back);
-               (*pskb)->nfcache |= e->nfcache;
                if (ip6_packet_match(*pskb, indev, outdev, &e->ipv6,
                        &protoff, &offset)) {
                        struct ip6t_entry_target *t;
index d09ceb0..81924fc 100644 (file)
@@ -28,10 +28,9 @@ target(struct sk_buff **pskb,
 {
        const struct ip6t_mark_target_info *markinfo = targinfo;
 
-       if((*pskb)->nfmark != markinfo->mark) {
+       if((*pskb)->nfmark != markinfo->mark)
                (*pskb)->nfmark = markinfo->mark;
-               (*pskb)->nfcache |= NFC_ALTERED;
-       }
+
        return IP6T_CONTINUE;
 }