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authorJesper Dangaard Brouer <brouer@redhat.com>2013-08-14 23:47:11 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-09-14 06:54:55 -0700
commitc06ab09127706af38e9e2869afef82a0f63e5fd7 (patch)
treec3db3c8155aa958ce6f991b5e178288cd8dc62f9
parent9f0bd377e1210501cd11eef80159e5d7f6160fef (diff)
net_sched: restore "linklayer atm" handling
[ Upstream commit 8a8e3d84b1719a56f9151909e80ea6ebc5b8e318 ] commit 56b765b79 ("htb: improved accuracy at high rates") broke the "linklayer atm" handling. tc class add ... htb rate X ceil Y linklayer atm The linklayer setting is implemented by modifying the rate table which is send to the kernel. No direct parameter were transferred to the kernel indicating the linklayer setting. The commit 56b765b79 ("htb: improved accuracy at high rates") removed the use of the rate table system. To keep compatible with older iproute2 utils, this patch detects the linklayer by parsing the rate table. It also supports future versions of iproute2 to send this linklayer parameter to the kernel directly. This is done by using the __reserved field in struct tc_ratespec, to convey the choosen linklayer option, but only using the lower 4 bits of this field. Linklayer detection is limited to speeds below 100Mbit/s, because at high rates the rtab is gets too inaccurate, so bad that several fields contain the same values, this resembling the ATM detect. Fields even start to contain "0" time to send, e.g. at 1000Mbit/s sending a 96 bytes packet cost "0", thus the rtab have been more broken than we first realized. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--include/net/sch_generic.h9
-rw-r--r--include/uapi/linux/pkt_sched.h10
-rw-r--r--net/sched/sch_api.c41
-rw-r--r--net/sched/sch_generic.c1
-rw-r--r--net/sched/sch_htb.c13
5 files changed, 72 insertions, 2 deletions
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index e7f4e21cc3e1..63ed1d1dd9e7 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -682,13 +682,19 @@ struct psched_ratecfg {
u64 rate_bps;
u32 mult;
u16 overhead;
+ u8 linklayer;
u8 shift;
};
static inline u64 psched_l2t_ns(const struct psched_ratecfg *r,
unsigned int len)
{
- return ((u64)(len + r->overhead) * r->mult) >> r->shift;
+ len += r->overhead;
+
+ if (unlikely(r->linklayer == TC_LINKLAYER_ATM))
+ return ((u64)(DIV_ROUND_UP(len,48)*53) * r->mult) >> r->shift;
+
+ return ((u64)len * r->mult) >> r->shift;
}
extern void psched_ratecfg_precompute(struct psched_ratecfg *r, const struct tc_ratespec *conf);
@@ -699,6 +705,7 @@ static inline void psched_ratecfg_getrate(struct tc_ratespec *res,
memset(res, 0, sizeof(*res));
res->rate = r->rate_bps >> 3;
res->overhead = r->overhead;
+ res->linklayer = (r->linklayer & TC_LINKLAYER_MASK);
}
#endif
diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h
index dbd71b0c7d8c..09d62b9228ff 100644
--- a/include/uapi/linux/pkt_sched.h
+++ b/include/uapi/linux/pkt_sched.h
@@ -73,9 +73,17 @@ struct tc_estimator {
#define TC_H_ROOT (0xFFFFFFFFU)
#define TC_H_INGRESS (0xFFFFFFF1U)
+/* Need to corrospond to iproute2 tc/tc_core.h "enum link_layer" */
+enum tc_link_layer {
+ TC_LINKLAYER_UNAWARE, /* Indicate unaware old iproute2 util */
+ TC_LINKLAYER_ETHERNET,
+ TC_LINKLAYER_ATM,
+};
+#define TC_LINKLAYER_MASK 0x0F /* limit use to lower 4 bits */
+
struct tc_ratespec {
unsigned char cell_log;
- unsigned char __reserved;
+ __u8 linklayer; /* lower 4 bits */
unsigned short overhead;
short cell_align;
unsigned short mpu;
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 281c1bded1f6..51b968d3febb 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -285,6 +285,45 @@ static struct Qdisc_ops *qdisc_lookup_ops(struct nlattr *kind)
return q;
}
+/* The linklayer setting were not transferred from iproute2, in older
+ * versions, and the rate tables lookup systems have been dropped in
+ * the kernel. To keep backward compatible with older iproute2 tc
+ * utils, we detect the linklayer setting by detecting if the rate
+ * table were modified.
+ *
+ * For linklayer ATM table entries, the rate table will be aligned to
+ * 48 bytes, thus some table entries will contain the same value. The
+ * mpu (min packet unit) is also encoded into the old rate table, thus
+ * starting from the mpu, we find low and high table entries for
+ * mapping this cell. If these entries contain the same value, when
+ * the rate tables have been modified for linklayer ATM.
+ *
+ * This is done by rounding mpu to the nearest 48 bytes cell/entry,
+ * and then roundup to the next cell, calc the table entry one below,
+ * and compare.
+ */
+static __u8 __detect_linklayer(struct tc_ratespec *r, __u32 *rtab)
+{
+ int low = roundup(r->mpu, 48);
+ int high = roundup(low+1, 48);
+ int cell_low = low >> r->cell_log;
+ int cell_high = (high >> r->cell_log) - 1;
+
+ /* rtab is too inaccurate at rates > 100Mbit/s */
+ if ((r->rate > (100000000/8)) || (rtab[0] == 0)) {
+ pr_debug("TC linklayer: Giving up ATM detection\n");
+ return TC_LINKLAYER_ETHERNET;
+ }
+
+ if ((cell_high > cell_low) && (cell_high < 256)
+ && (rtab[cell_low] == rtab[cell_high])) {
+ pr_debug("TC linklayer: Detected ATM, low(%d)=high(%d)=%u\n",
+ cell_low, cell_high, rtab[cell_high]);
+ return TC_LINKLAYER_ATM;
+ }
+ return TC_LINKLAYER_ETHERNET;
+}
+
static struct qdisc_rate_table *qdisc_rtab_list;
struct qdisc_rate_table *qdisc_get_rtab(struct tc_ratespec *r, struct nlattr *tab)
@@ -308,6 +347,8 @@ struct qdisc_rate_table *qdisc_get_rtab(struct tc_ratespec *r, struct nlattr *ta
rtab->rate = *r;
rtab->refcnt = 1;
memcpy(rtab->data, nla_data(tab), 1024);
+ if (r->linklayer == TC_LINKLAYER_UNAWARE)
+ r->linklayer = __detect_linklayer(r, rtab->data);
rtab->next = qdisc_rtab_list;
qdisc_rtab_list = rtab;
}
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 20224086cc28..a7f838b45dc8 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -908,6 +908,7 @@ void psched_ratecfg_precompute(struct psched_ratecfg *r,
memset(r, 0, sizeof(*r));
r->overhead = conf->overhead;
r->rate_bps = (u64)conf->rate << 3;
+ r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
r->mult = 1;
/*
* Calibrate mult, shift so that token counting is accurate
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 5c9f0b7b2109..910667cbc1e3 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -1312,6 +1312,7 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
struct htb_sched *q = qdisc_priv(sch);
struct htb_class *cl = (struct htb_class *)*arg, *parent;
struct nlattr *opt = tca[TCA_OPTIONS];
+ struct qdisc_rate_table *rtab = NULL, *ctab = NULL;
struct nlattr *tb[TCA_HTB_MAX + 1];
struct tc_htb_opt *hopt;
@@ -1333,6 +1334,18 @@ static int htb_change_class(struct Qdisc *sch, u32 classid,
if (!hopt->rate.rate || !hopt->ceil.rate)
goto failure;
+ /* Keeping backward compatible with rate_table based iproute2 tc */
+ if (hopt->rate.linklayer == TC_LINKLAYER_UNAWARE) {
+ rtab = qdisc_get_rtab(&hopt->rate, tb[TCA_HTB_RTAB]);
+ if (rtab)
+ qdisc_put_rtab(rtab);
+ }
+ if (hopt->ceil.linklayer == TC_LINKLAYER_UNAWARE) {
+ ctab = qdisc_get_rtab(&hopt->ceil, tb[TCA_HTB_CTAB]);
+ if (ctab)
+ qdisc_put_rtab(ctab);
+ }
+
if (!cl) { /* new class */
struct Qdisc *new_q;
int prio;