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Date: Tue, 9 Sep 2008 10:58:40 +0200
From: Thomas Graf <tgraf@...g.ch>
To: Ranjit Manomohan <ranjitm@...gle.com>
Cc: netdev@...r.kernel.org, Paul Menage <menage@...gle.com>
Subject: Re: [RFC] Control Group Classifier
* Thomas Graf <tgraf@...g.ch> 2008-09-09 02:06
> * Ranjit Manomohan <ranjitm@...gle.com> 2008-09-08 14:28
> > Wouldn't this cause a lot of packets (like acks) to be incorrectly
> > classifed to the current tasks cgroup although it may not have
> > anything to do with them? That is the reason I chose to put the
> > classid into the socket at creation time.
>
> In its current form, it does not work if the packet is rescheduled
> or not sent in the context of a process. Such packets simply end
> up not being classified at all. In the most common case, the packet
> is not queued before it hits the qdisc so this takes away a lot of
> complexity and is very fast but should still be sufficient.
Sorry, I just noticed that I actually missed to add the in_softirq()
check to the classification function. It only existed in my mind ;-)
Thanks for pointing this out!
Here is an updated patch with the classify function slightly changed.
Index: net-2.6-next/include/linux/cgroup_subsys.h
===================================================================
--- net-2.6-next.orig/include/linux/cgroup_subsys.h 2008-09-08 13:38:07.000000000 +0200
+++ net-2.6-next/include/linux/cgroup_subsys.h 2008-09-08 13:38:47.000000000 +0200
@@ -48,3 +48,9 @@
#endif
/* */
+
+#ifdef CONFIG_NET_CLS_CGROUP
+SUBSYS(net_cls)
+#endif
+
+/* */
Index: net-2.6-next/include/linux/pkt_cls.h
===================================================================
--- net-2.6-next.orig/include/linux/pkt_cls.h 2008-09-08 13:38:07.000000000 +0200
+++ net-2.6-next/include/linux/pkt_cls.h 2008-09-08 13:38:47.000000000 +0200
@@ -394,6 +394,20 @@
#define TCA_BASIC_MAX (__TCA_BASIC_MAX - 1)
+
+/* Cgroup classifier */
+
+enum
+{
+ TCA_CGROUP_UNSPEC,
+ TCA_CGROUP_ACT,
+ TCA_CGROUP_POLICE,
+ TCA_CGROUP_EMATCHES,
+ __TCA_CGROUP_MAX,
+};
+
+#define TCA_CGROUP_MAX (__TCA_CGROUP_MAX - 1)
+
/* Extended Matches */
struct tcf_ematch_tree_hdr
Index: net-2.6-next/net/sched/Kconfig
===================================================================
--- net-2.6-next.orig/net/sched/Kconfig 2008-09-08 13:38:07.000000000 +0200
+++ net-2.6-next/net/sched/Kconfig 2008-09-08 13:38:47.000000000 +0200
@@ -307,6 +307,17 @@
To compile this code as a module, choose M here: the
module will be called cls_flow.
+config NET_CLS_CGROUP
+ tristate "Control Group Classifier"
+ select NET_CLS
+ depends on CGROUPS
+ ---help---
+ Say Y here if you want to classify packets based on the control
+ cgroup of their process.
+
+ To compile this code as a module, choose M here: the
+ module will be called cls_cgroup.
+
config NET_EMATCH
bool "Extended Matches"
select NET_CLS
Index: net-2.6-next/net/sched/Makefile
===================================================================
--- net-2.6-next.orig/net/sched/Makefile 2008-09-08 13:38:07.000000000 +0200
+++ net-2.6-next/net/sched/Makefile 2008-09-08 13:38:47.000000000 +0200
@@ -36,6 +36,7 @@
obj-$(CONFIG_NET_CLS_RSVP6) += cls_rsvp6.o
obj-$(CONFIG_NET_CLS_BASIC) += cls_basic.o
obj-$(CONFIG_NET_CLS_FLOW) += cls_flow.o
+obj-$(CONFIG_NET_CLS_CGROUP) += cls_cgroup.o
obj-$(CONFIG_NET_EMATCH) += ematch.o
obj-$(CONFIG_NET_EMATCH_CMP) += em_cmp.o
obj-$(CONFIG_NET_EMATCH_NBYTE) += em_nbyte.o
Index: net-2.6-next/net/sched/cls_cgroup.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ net-2.6-next/net/sched/cls_cgroup.c 2008-09-09 10:54:06.000000000 +0200
@@ -0,0 +1,281 @@
+/*
+ * net/sched/cls_cgroup.c Control Group Classifier
+ *
+ * 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@...g.ch>
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/skbuff.h>
+#include <linux/cgroup.h>
+#include <net/rtnetlink.h>
+#include <net/pkt_cls.h>
+
+struct cgroup_cls_state
+{
+ struct cgroup_subsys_state css;
+ u32 classid;
+};
+
+static inline struct cgroup_cls_state *net_cls_state(struct cgroup *cgrp)
+{
+ return (struct cgroup_cls_state *)
+ cgroup_subsys_state(cgrp, net_cls_subsys_id);
+}
+
+static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
+ struct cgroup *cgrp)
+{
+ struct cgroup_cls_state *cs;
+
+ if (!(cs = kzalloc(sizeof(*cs), GFP_KERNEL)))
+ return ERR_PTR(-ENOMEM);
+
+ if (cgrp->parent)
+ cs->classid = net_cls_state(cgrp)->classid;
+
+ return &cs->css;
+}
+
+static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
+{
+ kfree(ss);
+}
+
+static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
+{
+ return net_cls_state(cgrp)->classid;
+}
+
+static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
+{
+ if (!cgroup_lock_live_group(cgrp))
+ return -ENODEV;
+
+ net_cls_state(cgrp)->classid = (u32) value;
+
+ cgroup_unlock();
+
+ return 0;
+}
+
+static struct cftype ss_files[] = {
+ {
+ .name = "classid",
+ .read_u64 = read_classid,
+ .write_u64 = write_classid,
+ },
+};
+
+static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
+{
+ return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
+}
+
+struct cgroup_subsys net_cls_subsys = {
+ .name = "net_cls",
+ .create = cgrp_create,
+ .destroy = cgrp_destroy,
+ .populate = cgrp_populate,
+ .subsys_id = net_cls_subsys_id,
+};
+
+struct cls_cgroup_head
+{
+ u32 handle;
+ struct tcf_exts exts;
+ struct tcf_ematch_tree ematches;
+};
+
+static int cls_cgroup_classify(struct sk_buff *skb, struct tcf_proto *tp,
+ struct tcf_result *res)
+{
+ struct cls_cgroup_head *head = tp->root;
+ struct cgroup_cls_state *cs;
+ int ret = 0;
+
+ if (in_softirq())
+ return -1;
+
+ rcu_read_lock();
+
+ cs = (struct cgroup_cls_state *) task_subsys_state(current,
+ net_cls_subsys_id);
+ if (cs->classid && tcf_em_tree_match(skb, &head->ematches, NULL)) {
+ res->classid = cs->classid;
+ res->class = 0;
+ ret = tcf_exts_exec(skb, &head->exts, res);
+ } else
+ ret = -1;
+
+ rcu_read_unlock();
+
+ return ret;
+}
+
+static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
+{
+ return 0UL;
+}
+
+static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
+{
+}
+
+static int cls_cgroup_init(struct tcf_proto *tp)
+{
+ return 0;
+}
+
+static const struct tcf_ext_map cgroup_ext_map = {
+ .action = TCA_CGROUP_ACT,
+ .police = TCA_CGROUP_POLICE,
+};
+
+static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
+ [TCA_CGROUP_EMATCHES] = { .type = NLA_NESTED },
+};
+
+static int cls_cgroup_change(struct tcf_proto *tp, unsigned long base,
+ u32 handle, struct nlattr **tca,
+ unsigned long *arg)
+{
+ struct nlattr *tb[TCA_CGROUP_MAX+1];
+ struct cls_cgroup_head *head = tp->root;
+ struct tcf_ematch_tree t;
+ struct tcf_exts e;
+ int err;
+
+ if (head == NULL) {
+ if (!handle)
+ return -EINVAL;
+
+ head = kzalloc(sizeof(*head), GFP_KERNEL);
+ if (head == NULL)
+ return -ENOBUFS;
+
+ head->handle = handle;
+
+ tcf_tree_lock(tp);
+ tp->root = head;
+ tcf_tree_unlock(tp);
+ }
+
+ if (handle != head->handle)
+ return -ENOENT;
+
+ err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
+ cgroup_policy);
+ if (err < 0)
+ return err;
+
+ err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
+ if (err < 0)
+ return err;
+
+ err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
+ if (err < 0)
+ return err;
+
+ tcf_exts_change(tp, &head->exts, &e);
+ tcf_em_tree_change(tp, &head->ematches, &t);
+
+ return 0;
+}
+
+static void cls_cgroup_destroy(struct tcf_proto *tp)
+{
+ struct cls_cgroup_head *head;
+
+ head = (struct cls_cgroup_head *)xchg(&tp->root, NULL);
+
+ if (head) {
+ tcf_exts_destroy(tp, &head->exts);
+ tcf_em_tree_destroy(tp, &head->ematches);
+ kfree(head);
+ }
+}
+
+static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
+{
+ return -EOPNOTSUPP;
+}
+
+static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
+{
+ struct cls_cgroup_head *head = tp->root;
+
+ if (arg->count < arg->skip)
+ goto skip;
+
+ if (arg->fn(tp, (unsigned long) head, arg) < 0) {
+ arg->stop = 1;
+ return;
+ }
+skip:
+ arg->count++;
+}
+
+static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
+ struct sk_buff *skb, struct tcmsg *t)
+{
+ struct cls_cgroup_head *head = tp->root;
+ unsigned char *b = skb_tail_pointer(skb);
+ struct nlattr *nest;
+
+ t->tcm_handle = head->handle;
+
+ nest = nla_nest_start(skb, TCA_OPTIONS);
+ if (nest == NULL)
+ goto nla_put_failure;
+
+ if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
+ tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
+ goto nla_put_failure;
+
+ nla_nest_end(skb, nest);
+
+ if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
+ goto nla_put_failure;
+
+ return skb->len;
+
+nla_put_failure:
+ nlmsg_trim(skb, b);
+ return -1;
+}
+
+static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
+ .kind = "cgroup",
+ .init = cls_cgroup_init,
+ .change = cls_cgroup_change,
+ .classify = cls_cgroup_classify,
+ .destroy = cls_cgroup_destroy,
+ .get = cls_cgroup_get,
+ .put = cls_cgroup_put,
+ .delete = cls_cgroup_delete,
+ .walk = cls_cgroup_walk,
+ .dump = cls_cgroup_dump,
+ .owner = THIS_MODULE,
+};
+
+static int __init init_cgroup_cls(void)
+{
+ return register_tcf_proto_ops(&cls_cgroup_ops);
+}
+
+static void __exit exit_cgroup_cls(void)
+{
+ unregister_tcf_proto_ops(&cls_cgroup_ops);
+}
+
+module_init(init_cgroup_cls);
+module_exit(exit_cgroup_cls);
+MODULE_LICENSE("GPL");
--
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