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authorPetr Machata <petrm@mellanox.com>2020-03-13 01:10:57 +0200
committerDavid S. Miller <davem@davemloft.net>2020-03-14 21:03:46 -0700
commit0a7fad2376ba6b37c6b1a1072ed2a2381d82cd18 (patch)
treececaf961e1015055ee4f9912de73fbd5d04f0722
parent14bc175d9c885c86239de3d730eea85ad67bfe7b (diff)
downloadlinux-0a7fad2376ba6b37c6b1a1072ed2a2381d82cd18.tar.bz2
net: sched: RED: Introduce an ECN nodrop mode
When the RED Qdisc is currently configured to enable ECN, the RED algorithm is used to decide whether a certain SKB should be marked. If that SKB is not ECN-capable, it is early-dropped. It is also possible to keep all traffic in the queue, and just mark the ECN-capable subset of it, as appropriate under the RED algorithm. Some switches support this mode, and some installations make use of it. To that end, add a new RED flag, TC_RED_NODROP. When the Qdisc is configured with this flag, non-ECT traffic is enqueued instead of being early-dropped. Signed-off-by: Petr Machata <petrm@mellanox.com> Reviewed-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/pkt_cls.h1
-rw-r--r--include/net/red.h5
-rw-r--r--include/uapi/linux/pkt_sched.h1
-rw-r--r--net/sched/sch_red.c31
4 files changed, 32 insertions, 6 deletions
diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
index dbc89452f90b..1db8b27d4515 100644
--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -740,6 +740,7 @@ struct tc_red_qopt_offload_params {
u32 limit;
bool is_ecn;
bool is_harddrop;
+ bool is_nodrop;
struct gnet_stats_queue *qstats;
};
diff --git a/include/net/red.h b/include/net/red.h
index 6a2aaa6c7c41..fc455445f4b2 100644
--- a/include/net/red.h
+++ b/include/net/red.h
@@ -209,6 +209,11 @@ static inline int red_get_flags(unsigned char qopt_flags,
static inline int red_validate_flags(unsigned char flags,
struct netlink_ext_ack *extack)
{
+ if ((flags & TC_RED_NODROP) && !(flags & TC_RED_ECN)) {
+ NL_SET_ERR_MSG_MOD(extack, "nodrop mode is only meaningful with ECN");
+ return -EINVAL;
+ }
+
return 0;
}
diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h
index 6325507935ea..ea39287d59c8 100644
--- a/include/uapi/linux/pkt_sched.h
+++ b/include/uapi/linux/pkt_sched.h
@@ -286,6 +286,7 @@ struct tc_red_qopt {
#define TC_RED_ECN 1
#define TC_RED_HARDDROP 2
#define TC_RED_ADAPTATIVE 4
+#define TC_RED_NODROP 8
};
#define TC_RED_HISTORIC_FLAGS (TC_RED_ECN | TC_RED_HARDDROP | TC_RED_ADAPTATIVE)
diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c
index d4ce111704dc..3ef0a4f7399b 100644
--- a/net/sched/sch_red.c
+++ b/net/sched/sch_red.c
@@ -48,7 +48,7 @@ struct red_sched_data {
struct Qdisc *qdisc;
};
-static const u32 red_supported_flags = TC_RED_HISTORIC_FLAGS;
+static const u32 red_supported_flags = TC_RED_HISTORIC_FLAGS | TC_RED_NODROP;
static inline int red_use_ecn(struct red_sched_data *q)
{
@@ -60,6 +60,11 @@ static inline int red_use_harddrop(struct red_sched_data *q)
return q->flags & TC_RED_HARDDROP;
}
+static int red_use_nodrop(struct red_sched_data *q)
+{
+ return q->flags & TC_RED_NODROP;
+}
+
static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
@@ -80,23 +85,36 @@ static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch,
case RED_PROB_MARK:
qdisc_qstats_overlimit(sch);
- if (!red_use_ecn(q) || !INET_ECN_set_ce(skb)) {
+ if (!red_use_ecn(q)) {
q->stats.prob_drop++;
goto congestion_drop;
}
- q->stats.prob_mark++;
+ if (INET_ECN_set_ce(skb)) {
+ q->stats.prob_mark++;
+ } else if (!red_use_nodrop(q)) {
+ q->stats.prob_drop++;
+ goto congestion_drop;
+ }
+
+ /* Non-ECT packet in ECN nodrop mode: queue it. */
break;
case RED_HARD_MARK:
qdisc_qstats_overlimit(sch);
- if (red_use_harddrop(q) || !red_use_ecn(q) ||
- !INET_ECN_set_ce(skb)) {
+ if (red_use_harddrop(q) || !red_use_ecn(q)) {
+ q->stats.forced_drop++;
+ goto congestion_drop;
+ }
+
+ if (INET_ECN_set_ce(skb)) {
+ q->stats.forced_mark++;
+ } else if (!red_use_nodrop(q)) {
q->stats.forced_drop++;
goto congestion_drop;
}
- q->stats.forced_mark++;
+ /* Non-ECT packet in ECN nodrop mode: queue it. */
break;
}
@@ -171,6 +189,7 @@ static int red_offload(struct Qdisc *sch, bool enable)
opt.set.limit = q->limit;
opt.set.is_ecn = red_use_ecn(q);
opt.set.is_harddrop = red_use_harddrop(q);
+ opt.set.is_nodrop = red_use_nodrop(q);
opt.set.qstats = &sch->qstats;
} else {
opt.command = TC_RED_DESTROY;