The linux traffic control mechanism has different ways to select the
correct class of a qdisc. A common way to do this is to use tc filters
that are directly attached to a qdisc. Another approach is to use the
iptables classify module. The latter one can reduce the amount of work
necessary to process a packet when iptables is already involved in the
packet classification.
The iptables module can be used in the postrouting chain of the mangle
table.
# iptables -F -t mangle
# iptables -X -t mangle
# iptables -t mangle -I POSTROUTING -j CLASSIFY --set-class 1:1337
A simple qdisc with two classes will now route the traffic to 1:1337
# tc qdisc del dev eth0 root
# tc qdisc add dev eth0 root handle 1: htb default 1
# tc class add dev eth0 parent 1: classid 1:1 htb rate 15kbit burst 0kbit
# tc class add dev eth0 parent 1: classid 1:1337 htb rate 250kbit burst 0kbit
# tc -s class show dev eth0
A similar test with an ath9k device will show a complete different
behavior. The default class 1:1 will be used and data is sent through.
This problem seems to be related to the fact that the shared member
variable sk_buff::priority is used to store the tc class id of an
outgoing packet. This variable is also used in other places for
different purposes. An example is the ieee80211_select_queue function
which always overwrites the priority of an outgoing skb.
This conflict can be resolved by an additional member variable
sk_buff::tc_class that is only used for the traffic control
classification.
Signed-off-by: Simon Wunderlich <siwu@xxxxxxxxxxxxxxxxxx>
Cc: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Cc: Patrick McHardy <kaber@xxxxxxxxx>
Cc: Jamal Hadi Salim <hadi@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Cc: "John W. Linville" <linville@xxxxxxxxxxxxx>
Cc: Marek Lindner <lindner_marek@xxxxxxxx>
Cc: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Cc: netfilter-devel@xxxxxxxxxxxxxxx
Cc: netfilter@xxxxxxxxxxxxxxx
Cc: coreteam@xxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Cc: linux-wireless@xxxxxxxxxxxxxxx
---
include/linux/skbuff.h | 2 ++
net/netfilter/xt_CLASSIFY.c | 4 ++--
net/sched/sch_atm.c | 4 ++--
net/sched/sch_cbq.c | 2 +-
net/sched/sch_drr.c | 4 ++--
net/sched/sch_dsmark.c | 4 ++--
net/sched/sch_generic.c | 2 +-
net/sched/sch_hfsc.c | 4 ++--
net/sched/sch_htb.c | 6 +++---
net/sched/sch_prio.c | 4 ++--
net/sched/sch_sfq.c | 8 ++++----
11 files changed, 23 insertions(+), 21 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 50db9b0..3ffc301 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -352,6 +352,7 @@ typedef unsigned char *sk_buff_data_t;
* @nf_bridge: Saved data about a bridged frame - see br_netfilter.c
* @skb_iif: ifindex of device we arrived on
* @tc_index: Traffic control index
+ * @tc_class: Classification index
* @tc_verd: traffic control verdict
* @rxhash: the packet hash computed on receive
* @queue_mapping: Queue mapping for multiqueue devices
@@ -439,6 +440,7 @@ struct sk_buff {
int skb_iif;
#ifdef CONFIG_NET_SCHED
+ __u32 tc_class; /* traffic control class */
__u16 tc_index; /* traffic control index */
#ifdef CONFIG_NET_CLS_ACT
__u16 tc_verd; /* traffic control verdict */
diff --git a/net/netfilter/xt_CLASSIFY.c b/net/netfilter/xt_CLASSIFY.c
index af9c4da..9b71957 100644
--- a/net/netfilter/xt_CLASSIFY.c
+++ b/net/netfilter/xt_CLASSIFY.c
@@ -1,5 +1,5 @@
/*
- * This is a module which is used for setting the skb->priority field
+ * This is a module which is used for setting the skb->tc_class field
* of an skb for qdisc classification.
*/
@@ -33,7 +33,7 @@ classify_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
const struct xt_classify_target_info *clinfo = par->targinfo;
- skb->priority = clinfo->priority;
+ skb->tc_class = clinfo->priority;
return XT_CONTINUE;
}
diff --git a/net/sched/sch_atm.c b/net/sched/sch_atm.c
index e25e490..003511a 100644
--- a/net/sched/sch_atm.c
+++ b/net/sched/sch_atm.c
@@ -369,8 +369,8 @@ static int atm_tc_enqueue(struct sk_buff *skb, struct Qdisc *sch)
pr_debug("atm_tc_enqueue(skb %p,sch %p,[qdisc %p])\n", skb, sch, p);
result = TC_POLICE_OK; /* be nice to gcc */
flow = NULL;
- if (TC_H_MAJ(skb->priority) != sch->handle ||
- !(flow = (struct atm_flow_data *)atm_tc_get(sch, skb->priority))) {
+ if (TC_H_MAJ(skb->tc_class) != sch->handle ||
+ !(flow = (struct atm_flow_data *)atm_tc_get(sch, skb->tc_class))) {
list_for_each_entry(flow, &p->flows, list) {
if (flow->filter_list) {
result = tc_classify_compat(skb,
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index 24d94c0..b1321f9 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -221,7 +221,7 @@ cbq_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
struct cbq_class *head = &q->link;
struct cbq_class **defmap;
struct cbq_class *cl = NULL;
- u32 prio = skb->priority;
+ u32 prio = skb->tc_class;
struct tcf_result res;
/*
diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c
index 6b7fe4a..57b1ca2 100644
--- a/net/sched/sch_drr.c
+++ b/net/sched/sch_drr.c
@@ -321,8 +321,8 @@ static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
struct tcf_result res;
int result;
- if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
- cl = drr_find_class(sch, skb->priority);
+ if (TC_H_MAJ(skb->tc_class ^ sch->handle) == 0) {
+ cl = drr_find_class(sch, skb->tc_class);
if (cl != NULL)
return cl;
}
diff --git a/net/sched/sch_dsmark.c b/net/sched/sch_dsmark.c
index 2c79020..60cfe15 100644
--- a/net/sched/sch_dsmark.c
+++ b/net/sched/sch_dsmark.c
@@ -224,8 +224,8 @@ static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch)
}
}
- if (TC_H_MAJ(skb->priority) == sch->handle)
- skb->tc_index = TC_H_MIN(skb->priority);
+ if (TC_H_MAJ(skb->tc_class) == sch->handle)
+ skb->tc_index = TC_H_MIN(skb->tc_class);
else {
struct tcf_result res;
int result = tc_classify(skb, p->filter_list, &res);
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 67fc573..c14779a 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -449,7 +449,7 @@ static inline struct sk_buff_head *band2list(struct pfifo_fast_priv *priv,
static int pfifo_fast_enqueue(struct sk_buff *skb, struct Qdisc *qdisc)
{
if (skb_queue_len(&qdisc->q) < qdisc_dev(qdisc)->tx_queue_len) {
- int band = prio2band[skb->priority & TC_PRIO_MAX];
+ int band = prio2band[skb->tc_class & TC_PRIO_MAX];
struct pfifo_fast_priv *priv = qdisc_priv(qdisc);
struct sk_buff_head *list = band2list(priv, band);
diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index 9bdca2e..2fcc6ef 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -1154,8 +1154,8 @@ hfsc_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
struct tcf_proto *tcf;
int result;
- if (TC_H_MAJ(skb->priority ^ sch->handle) == 0 &&
- (cl = hfsc_find_class(skb->priority, sch)) != NULL)
+ if (TC_H_MAJ(skb->tc_class ^ sch->handle) == 0 &&
+ (cl = hfsc_find_class(skb->tc_class, sch)) != NULL)
if (cl->level == 0)
return cl;
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 29b942c..ef8dd42 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -197,13 +197,13 @@ static struct htb_class *htb_classify(struct sk_buff *skb, struct Qdisc *sch,
struct tcf_proto *tcf;
int result;
- /* allow to select class by setting skb->priority to valid classid;
+ /* allow to select class by setting skb->tc_class to valid classid;
* note that nfmark can be used too by attaching filter fw with no
* rules in it
*/
- if (skb->priority == sch->handle)
+ if (skb->tc_class == sch->handle)
return HTB_DIRECT; /* X:0 (direct flow) selected */
- cl = htb_find(skb->priority, sch);
+ cl = htb_find(skb->tc_class, sch);
if (cl && cl->level == 0)
return cl;
diff --git a/net/sched/sch_prio.c b/net/sched/sch_prio.c
index b5d56a2..f53a5b99 100644
--- a/net/sched/sch_prio.c
+++ b/net/sched/sch_prio.c
@@ -34,12 +34,12 @@ static struct Qdisc *
prio_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
{
struct prio_sched_data *q = qdisc_priv(sch);
- u32 band = skb->priority;
+ u32 band = skb->tc_class;
struct tcf_result res;
int err;
*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
- if (TC_H_MAJ(skb->priority) != sch->handle) {
+ if (TC_H_MAJ(skb->tc_class) != sch->handle) {
err = tc_classify(skb, q->filter_list, &res);
#ifdef CONFIG_NET_CLS_ACT
switch (err) {
diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index 67494ae..79bc0ac 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -190,10 +190,10 @@ static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch,
struct tcf_result res;
int result;
- if (TC_H_MAJ(skb->priority) == sch->handle &&
- TC_H_MIN(skb->priority) > 0 &&
- TC_H_MIN(skb->priority) <= q->divisor)
- return TC_H_MIN(skb->priority);
+ if (TC_H_MAJ(skb->tc_class) == sch->handle &&
+ TC_H_MIN(skb->tc_class) > 0 &&
+ TC_H_MIN(skb->tc_class) <= q->divisor)
+ return TC_H_MIN(skb->tc_class);
if (!q->filter_list) {
skb_flow_dissect(skb, &sfq_skb_cb(skb)->keys);
--
1.7.8.3
--
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