@@ -727,6 +727,7 @@ struct tc_red_qopt_offload_params {
u32 limit;
bool is_ecn;
bool is_harddrop;
+ bool is_nodrop;
struct gnet_stats_queue *qstats;
};
@@ -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;
}
@@ -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)
@@ -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;
}
- q->stats.forced_mark++;
+ if (INET_ECN_set_ce(skb)) {
+ q->stats.forced_mark++;
+ } else if (!red_use_nodrop(q)) {
+ q->stats.forced_drop++;
+ goto congestion_drop;
+ }
+
+ /* 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;
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> --- Notes: v3: - Rename "taildrop" to "nodrop" - Make red_use_nodrop() static instead of static inline v2: - Fix red_use_taildrop() condition in red_enqueue switch for probabilistic case. include/net/pkt_cls.h | 1 + include/net/red.h | 5 +++++ include/uapi/linux/pkt_sched.h | 1 + net/sched/sch_red.c | 31 +++++++++++++++++++++++++------ 4 files changed, 32 insertions(+), 6 deletions(-)