taprio: Add support for setting the cycle-time manually

IEEE 802.1Q-2018 defines that a the cycle-time of a schedule may be
overridden, so the schedule is truncated to a determined "width".

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h
index d59770d0eb843eef313aa9f8ad65d17e5381c769..7a32276838e19fb07963e82951289b640c2398d2 100644 (file)
--- a/include/uapi/linux/pkt_sched.h
+++ b/include/uapi/linux/pkt_sched.h
@@ -1167,6 +1167,7 @@ enum {
        TCA_TAPRIO_ATTR_SCHED_CLOCKID, /* s32 */
        TCA_TAPRIO_PAD,
        TCA_TAPRIO_ATTR_ADMIN_SCHED, /* The admin sched, only used in dump */
+       TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME, /* s64 */
        __TCA_TAPRIO_ATTR_MAX,
 };
 

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index ec8ccaee64e657d52dbedd431b21241f9381cd6a..6b37ffda23ecd821c9192913a832b44673bfa523 100644 (file)
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -46,6 +46,8 @@ struct sched_gate_list {
        struct rcu_head rcu;
        struct list_head entries;
        size_t num_entries;
+       ktime_t cycle_close_time;
+       s64 cycle_time;
        s64 base_time;
 };
 
@@ -105,6 +107,22 @@ static void switch_schedules(struct taprio_sched *q,
        *admin = NULL;
 }
 
+static ktime_t get_cycle_time(struct sched_gate_list *sched)
+{
+       struct sched_entry *entry;
+       ktime_t cycle = 0;
+
+       if (sched->cycle_time != 0)
+               return sched->cycle_time;
+
+       list_for_each_entry(entry, &sched->entries, list)
+               cycle = ktime_add_ns(cycle, entry->interval);
+
+       sched->cycle_time = cycle;
+
+       return cycle;
+}
+
 static int taprio_enqueue(struct sk_buff *skb, struct Qdisc *sch,
                          struct sk_buff **to_free)
 {
@@ -256,6 +274,18 @@ done:
        return skb;
 }
 
+static bool should_restart_cycle(const struct sched_gate_list *oper,
+                                const struct sched_entry *entry)
+{
+       if (list_is_last(&entry->list, &oper->entries))
+               return true;
+
+       if (ktime_compare(entry->close_time, oper->cycle_close_time) == 0)
+               return true;
+
+       return false;
+}
+
 static bool should_change_schedules(const struct sched_gate_list *admin,
                                    const struct sched_gate_list *oper,
                                    ktime_t close_time)
@@ -309,13 +339,17 @@ static enum hrtimer_restart advance_sched(struct hrtimer *timer)
                goto first_run;
        }
 
-       if (list_is_last(&entry->list, &oper->entries))
+       if (should_restart_cycle(oper, entry)) {
                next = list_first_entry(&oper->entries, struct sched_entry,
                                        list);
-       else
+               oper->cycle_close_time = ktime_add_ns(oper->cycle_close_time,
+                                                     oper->cycle_time);
+       } else {
                next = list_next_entry(entry, list);
+       }
 
        close_time = ktime_add_ns(entry->close_time, next->interval);
+       close_time = min_t(ktime_t, close_time, oper->cycle_close_time);
 
        if (should_change_schedules(admin, oper, close_time)) {
                /* Set things so the next time this runs, the new
@@ -360,6 +394,7 @@ static const struct nla_policy taprio_policy[TCA_TAPRIO_ATTR_MAX + 1] = {
        [TCA_TAPRIO_ATTR_SCHED_BASE_TIME]      = { .type = NLA_S64 },
        [TCA_TAPRIO_ATTR_SCHED_SINGLE_ENTRY]   = { .type = NLA_NESTED },
        [TCA_TAPRIO_ATTR_SCHED_CLOCKID]        = { .type = NLA_S32 },
+       [TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME]     = { .type = NLA_S64 },
 };
 
 static int fill_sched_entry(struct nlattr **tb, struct sched_entry *entry,
@@ -461,6 +496,9 @@ static int parse_taprio_schedule(struct nlattr **tb,
        if (tb[TCA_TAPRIO_ATTR_SCHED_BASE_TIME])
                new->base_time = nla_get_s64(tb[TCA_TAPRIO_ATTR_SCHED_BASE_TIME]);
 
+       if (tb[TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME])
+               new->cycle_time = nla_get_s64(tb[TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME]);
+
        if (tb[TCA_TAPRIO_ATTR_SCHED_ENTRY_LIST])
                err = parse_sched_list(
                        tb[TCA_TAPRIO_ATTR_SCHED_ENTRY_LIST], new, extack);
@@ -537,7 +575,6 @@ static int taprio_get_start_time(struct Qdisc *sch,
                                 ktime_t *start)
 {
        struct taprio_sched *q = qdisc_priv(sch);
-       struct sched_entry *entry;
        ktime_t now, base, cycle;
        s64 n;
 
@@ -549,11 +586,7 @@ static int taprio_get_start_time(struct Qdisc *sch,
                return 0;
        }
 
-       /* Calculate the cycle_time, by summing all the intervals.
-        */
-       cycle = 0;
-       list_for_each_entry(entry, &sched->entries, list)
-               cycle = ktime_add_ns(cycle, entry->interval);
+       cycle = get_cycle_time(sched);
 
        /* The qdisc is expected to have at least one sched_entry.  Moreover,
         * any entry must have 'interval' > 0. Thus if the cycle time is zero,
@@ -575,10 +608,16 @@ static void setup_first_close_time(struct taprio_sched *q,
                                   struct sched_gate_list *sched, ktime_t base)
 {
        struct sched_entry *first;
+       ktime_t cycle;
 
        first = list_first_entry(&sched->entries,
                                 struct sched_entry, list);
 
+       cycle = get_cycle_time(sched);
+
+       /* FIXME: find a better place to do this */
+       sched->cycle_close_time = ktime_add_ns(base, cycle);
+
        first->close_time = ktime_add_ns(base, first->interval);
        taprio_set_budget(q, first);
        rcu_assign_pointer(q->current_entry, NULL);
@@ -965,6 +1004,10 @@ static int dump_schedule(struct sk_buff *msg,
                        root->base_time, TCA_TAPRIO_PAD))
                return -1;
 
+       if (nla_put_s64(msg, TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME,
+                       root->cycle_time, TCA_TAPRIO_PAD))
+               return -1;
+
        entry_list = nla_nest_start_noflag(msg,
                                           TCA_TAPRIO_ATTR_SCHED_ENTRY_LIST);
        if (!entry_list)