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Re: [RFC] ematch API, u32 ematch, nbyte ematch, basic classifier

To: jamal <hadi@xxxxxxxxxx>
Subject: Re: [RFC] ematch API, u32 ematch, nbyte ematch, basic classifier
From: Thomas Graf <tgraf@xxxxxxx>
Date: Wed, 5 Jan 2005 17:48:32 +0100
Cc: netdev@xxxxxxxxxxx
In-reply-to: <20050105144514.GQ26856@xxxxxxxxxxxxxx>
References: <20050103125635.GB26856@xxxxxxxxxxxxxx> <20050104223612.GN26856@xxxxxxxxxxxxxx> <1104894728.1117.56.camel@xxxxxxxxxxxxxxxx> <20050105110048.GO26856@xxxxxxxxxxxxxx> <1104931991.1117.152.camel@xxxxxxxxxxxxxxxx> <20050105144514.GQ26856@xxxxxxxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
> Most importantly I don't want to touch any of the hashing code in u32.
> I really like and it should stay as it is. The existing u32 match can
> be easly made an ematch so this would safe us the extra work in u32 to
> implement logic relations again and to fiddle with complicated selector
> TLVs. The only problem with this is the nexthdr bits because it relies
> on the hashing code. So we have to make this data available to the
> ematch which is actually not a bad idea anyway. So I'm thinking about
> introducing a new structure tcf_em_pkt_info or alike which carries
> some additional information found out by the classifiers which can be
> used by ematches. This can be information about the next header,
> already extracted dscp values, etc.

Here's what I mean, it moves the u32 match as-is to an ematch so it
benefits from logic relations, inversion and can be used from other
classifiers as well. All we have to do is set info->ptr and
info->nexthdr to ptr respetively off2 before we evaluate the ematch
tree. The pkt_info struct is then passed to tcf_em_tree_match and
made available to every ematch.

Thoughts?

diff -Nru linux-2.6.10-bk8.orig/include/linux/pkt_cls.h 
linux-2.6.10-bk8/include/linux/pkt_cls.h
--- linux-2.6.10-bk8.orig/include/linux/pkt_cls.h       2005-01-05 
17:40:02.000000000 +0100
+++ linux-2.6.10-bk8/include/linux/pkt_cls.h    2005-01-05 17:38:42.000000000 
+0100
@@ -351,6 +351,7 @@
        TCF_EM_CONTAINER,
        TCF_EM_CMP,
        TCF_EM_NBYTE,
+       TCF_EM_U32,
        __TCF_EM_MAX
 };
 
diff -Nru linux-2.6.10-bk8.orig/include/net/pkt_cls.h 
linux-2.6.10-bk8/include/net/pkt_cls.h
--- linux-2.6.10-bk8.orig/include/net/pkt_cls.h 2005-01-05 17:40:02.000000000 
+0100
+++ linux-2.6.10-bk8/include/net/pkt_cls.h      2005-01-05 17:39:08.000000000 
+0100
@@ -274,6 +274,8 @@
 
 struct tcf_pkt_info
 {
+       u8 *                    ptr;
+       int                     nexthdr;
 };
 
 static inline u32 tcf_read_bucket(u8 *ptr, u8 align)
diff -Nru linux-2.6.10-bk8.orig/net/sched/Kconfig 
linux-2.6.10-bk8/net/sched/Kconfig
--- linux-2.6.10-bk8.orig/net/sched/Kconfig     2005-01-05 17:38:26.000000000 
+0100
+++ linux-2.6.10-bk8/net/sched/Kconfig  2005-01-05 17:41:59.000000000 +0100
@@ -408,6 +408,12 @@
          To compile this code as a module, choose M here: the
          module will be called em_nbyte.
 
+config NET_EMATCH_U32
+       tristate "U32 hashing key"
+       depends on NET_EMATCH
+       ---help---
+         TODO
+
 config NET_CLS_ACT
        bool "Packet ACTION"
        depends on EXPERIMENTAL && NET_CLS && NET_QOS
diff -Nru linux-2.6.10-bk8.orig/net/sched/Makefile 
linux-2.6.10-bk8/net/sched/Makefile
--- linux-2.6.10-bk8.orig/net/sched/Makefile    2005-01-05 17:38:26.000000000 
+0100
+++ linux-2.6.10-bk8/net/sched/Makefile 2005-01-05 17:40:15.000000000 +0100
@@ -36,3 +36,4 @@
 obj-$(CONFIG_NET_EMATCH)       += ematch.o
 obj-$(CONFIG_NET_EMATCH_CMP)   += em_cmp.o
 obj-$(CONFIG_NET_EMATCH_NBYTE) += em_nbyte.o
+obj-$(CONFIG_NET_EMATCH_U32)   += em_u32.o
diff -Nru linux-2.6.10-bk8.orig/net/sched/em_u32.c 
linux-2.6.10-bk8/net/sched/em_u32.c
--- linux-2.6.10-bk8.orig/net/sched/em_u32.c    1970-01-01 01:00:00.000000000 
+0100
+++ linux-2.6.10-bk8/net/sched/em_u32.c 2005-01-05 17:38:42.000000000 +0100
@@ -0,0 +1,53 @@
+/*
+ * net/sched/em_u32.c  U32 Ematch
+ *
+ *             This program is free software; you can redistribute it and/or
+ *             modify it under the terms of the GNU General Public License
+ *             as published by the Free Software Foundation; either version
+ *             2 of the License, or (at your option) any later version.
+ *
+ * Authors:    Thomas Graf <tgraf@xxxxxxx>
+ *             Alexey Kuznetsov, <kuznet@xxxxxxxxxxxxx>
+ *
+ * Based on net/sched/cls_u32.c
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <net/pkt_cls.h>
+
+static int em_u32_match(struct sk_buff *skb, struct tcf_ematch *m,
+                       struct tcf_pkt_info *info)
+{
+       struct tc_u32_key *k = (struct tc_u32_key *) m->data;
+       u8 *ptr = info->ptr + k->off + (info->nexthdr & k->offmask);
+
+       return !((*(u32*) ptr ^ k->val) & k->mask);
+}
+
+static struct tcf_ematch_ops em_u32_ops = {
+       .kind     = TCF_EM_U32,
+       .datalen  = sizeof(struct tc_u32_key),
+       .match    = em_u32_match,
+       .owner    = THIS_MODULE,
+       .link     = LIST_HEAD_INIT(em_u32_ops.link)
+};
+
+static int __init init_em_u32(void)
+{
+       return tcf_em_register(&em_u32_ops);
+}
+
+static void __exit exit_em_u32(void) 
+{
+       tcf_em_unregister(&em_u32_ops);
+}
+
+MODULE_LICENSE("GPL");
+
+module_init(init_em_u32);
+module_exit(exit_em_u32);
+

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