From: Chia-Yu Chang <chia-yu.ch...@nokia-bell-labs.com>

The configuration and statistics dump of the DualPI2 Qdisc provides
information related to both queues, such as packet numbers and queuing
delays in the L-queue and C-queue, as well as general information such as
probability value, WRR credits, memory usage, packet marking counters, max
queue size, etc.

The following patch includes enqueue/dequeue for DualPI2.

Signed-off-by: Chia-Yu Chang <chia-yu.ch...@nokia-bell-labs.com>

---
v17:
- Replace 0xffffffff with U32_MAX
- Add READ_ONCE() in dualpi2_dump_stats()
v16:
- Update convert_ns_to_usec() to avoid overflow
---
 include/uapi/linux/pkt_sched.h | 15 ++++++
 net/sched/sch_dualpi2.c        | 89 ++++++++++++++++++++++++++++++++++
 2 files changed, 104 insertions(+)

diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h
index ae8af0e8d479..a7243f32ff0f 100644
--- a/include/uapi/linux/pkt_sched.h
+++ b/include/uapi/linux/pkt_sched.h
@@ -1264,4 +1264,19 @@ enum {
 
 #define TCA_DUALPI2_MAX   (__TCA_DUALPI2_MAX - 1)
 
+struct tc_dualpi2_xstats {
+       __u32 prob;             /* current probability */
+       __u32 delay_c;          /* current delay in C queue */
+       __u32 delay_l;          /* current delay in L queue */
+       __u32 packets_in_c;     /* number of packets enqueued in C queue */
+       __u32 packets_in_l;     /* number of packets enqueued in L queue */
+       __u32 maxq;             /* maximum queue size */
+       __u32 ecn_mark;         /* packets marked with ecn*/
+       __u32 step_marks;       /* ECN marks due to the step AQM */
+       __s32 credit;           /* current c_protection credit */
+       __u32 memory_used;      /* Memory used of both queues */
+       __u32 max_memory_used;  /* Maximum used memory */
+       __u32 memory_limit;     /* Memory limit of both queues */
+};
+
 #endif
diff --git a/net/sched/sch_dualpi2.c b/net/sched/sch_dualpi2.c
index 6c510bc321d2..2d7a83cc03f2 100644
--- a/net/sched/sch_dualpi2.c
+++ b/net/sched/sch_dualpi2.c
@@ -123,6 +123,14 @@ static u32 dualpi2_scale_alpha_beta(u32 param)
        return tmp;
 }
 
+static u32 dualpi2_unscale_alpha_beta(u32 param)
+{
+       u64 tmp = ((u64)param * NSEC_PER_SEC << ALPHA_BETA_SCALING);
+
+       do_div(tmp, MAX_PROB);
+       return tmp;
+}
+
 static ktime_t next_pi2_timeout(struct dualpi2_sched_data *q)
 {
        return ktime_add_ns(ktime_get_ns(), q->pi2_tupdate);
@@ -227,6 +235,15 @@ static u32 convert_us_to_nsec(u32 us)
                return lower_32_bits(ns);
 }
 
+static u32 convert_ns_to_usec(u64 ns)
+{
+       do_div(ns, NSEC_PER_USEC);
+       if (upper_32_bits(ns))
+               return U32_MAX;
+       else
+               return lower_32_bits(ns);
+}
+
 static enum hrtimer_restart dualpi2_timer(struct hrtimer *timer)
 {
        struct dualpi2_sched_data *q = from_timer(q, timer, pi2_timer);
@@ -462,6 +479,76 @@ static int dualpi2_init(struct Qdisc *sch, struct nlattr 
*opt,
        return 0;
 }
 
+static int dualpi2_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+       struct dualpi2_sched_data *q = qdisc_priv(sch);
+       struct nlattr *opts;
+
+       opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
+       if (!opts)
+               goto nla_put_failure;
+
+       if (nla_put_u32(skb, TCA_DUALPI2_LIMIT, READ_ONCE(sch->limit)) ||
+           nla_put_u32(skb, TCA_DUALPI2_MEMORY_LIMIT,
+                       READ_ONCE(q->memory_limit)) ||
+           nla_put_u32(skb, TCA_DUALPI2_TARGET,
+                       convert_ns_to_usec(READ_ONCE(q->pi2_target))) ||
+           nla_put_u32(skb, TCA_DUALPI2_TUPDATE,
+                       convert_ns_to_usec(READ_ONCE(q->pi2_tupdate))) ||
+           nla_put_u32(skb, TCA_DUALPI2_ALPHA,
+                       dualpi2_unscale_alpha_beta(READ_ONCE(q->pi2_alpha))) ||
+           nla_put_u32(skb, TCA_DUALPI2_BETA,
+                       dualpi2_unscale_alpha_beta(READ_ONCE(q->pi2_beta))) ||
+           nla_put_u32(skb, TCA_DUALPI2_STEP_THRESH,
+                       READ_ONCE(q->step_in_packets) ?
+                       READ_ONCE(q->step_thresh) :
+                       convert_ns_to_usec(READ_ONCE(q->step_thresh))) ||
+           nla_put_u32(skb, TCA_DUALPI2_MIN_QLEN_STEP,
+                       READ_ONCE(q->min_qlen_step)) ||
+           nla_put_u8(skb, TCA_DUALPI2_COUPLING,
+                      READ_ONCE(q->coupling_factor)) ||
+           nla_put_u8(skb, TCA_DUALPI2_DROP_OVERLOAD,
+                      READ_ONCE(q->drop_overload)) ||
+           (READ_ONCE(q->step_in_packets) &&
+            nla_put_flag(skb, TCA_DUALPI2_STEP_PACKETS)) ||
+           nla_put_u8(skb, TCA_DUALPI2_DROP_EARLY,
+                      READ_ONCE(q->drop_early)) ||
+           nla_put_u8(skb, TCA_DUALPI2_C_PROTECTION,
+                      READ_ONCE(q->c_protection_wc)) ||
+           nla_put_u8(skb, TCA_DUALPI2_ECN_MASK, READ_ONCE(q->ecn_mask)) ||
+           nla_put_u8(skb, TCA_DUALPI2_SPLIT_GSO, READ_ONCE(q->split_gso)))
+               goto nla_put_failure;
+
+       return nla_nest_end(skb, opts);
+
+nla_put_failure:
+       nla_nest_cancel(skb, opts);
+       return -1;
+}
+
+static int dualpi2_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
+{
+       struct dualpi2_sched_data *q = qdisc_priv(sch);
+       struct tc_dualpi2_xstats st = {
+               .prob                   = READ_ONCE(q->pi2_prob),
+               .packets_in_c           = READ_ONCE(q->packets_in_c),
+               .packets_in_l           = READ_ONCE(q->packets_in_l),
+               .maxq                   = READ_ONCE(q->maxq),
+               .ecn_mark               = READ_ONCE(q->ecn_mark),
+               .credit                 = READ_ONCE(q->c_protection_credit),
+               .step_marks             = READ_ONCE(q->step_marks),
+               .memory_used            = READ_ONCE(q->memory_used),
+               .max_memory_used        = READ_ONCE(q->max_memory_used),
+               .memory_limit           = READ_ONCE(q->memory_limit),
+       };
+       u64 qc, ql;
+
+       get_queue_delays(q, &qc, &ql);
+       st.delay_l = convert_ns_to_usec(ql);
+       st.delay_c = convert_ns_to_usec(qc);
+       return gnet_stats_copy_app(d, &st, sizeof(st));
+}
+
 /* Reset both L-queue and C-queue, internal packet counters, PI probability,
  * C-queue protection credit, and timestamps, while preserving current
  * configuration of DUALPI2.
@@ -566,6 +653,8 @@ static struct Qdisc_ops dualpi2_qdisc_ops __read_mostly = {
        .destroy        = dualpi2_destroy,
        .reset          = dualpi2_reset,
        .change         = dualpi2_change,
+       .dump           = dualpi2_dump,
+       .dump_stats     = dualpi2_dump_stats,
        .owner          = THIS_MODULE,
 };
 
-- 
2.34.1


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