kernel: merge a pending fix for HFSC warnings/slowdowns (fixes FS#1136)

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/target/linux/generic/patches-4.4/620-net_sched-codel-do-not-defer-queue-length-update.patch b/target/linux/generic/patches-4.4/620-net_sched-codel-do-not-defer-queue-length-update.patch
new file mode 100644 (file)
index 0000000..2ec9c7a
--- /dev/null
+++ b/target/linux/generic/patches-4.4/620-net_sched-codel-do-not-defer-queue-length-update.patch
@@ -0,0 +1,86 @@
+From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Date: Mon, 21 Aug 2017 11:14:14 +0300
+Subject: [PATCH] net_sched/codel: do not defer queue length update
+
+When codel wants to drop last packet in ->dequeue() it cannot call
+qdisc_tree_reduce_backlog() right away - it will notify parent qdisc
+about zero qlen and HTB/HFSC will deactivate class. The same class will
+be deactivated second time by caller of ->dequeue(). Currently codel and
+fq_codel defer update. This triggers warning in HFSC when it's qlen != 0
+but there is no active classes.
+
+This patch update parent queue length immediately: just temporary increase
+qlen around qdisc_tree_reduce_backlog() to prevent first class deactivation
+if we have skb to return.
+
+This might open another problem in HFSC - now operation peek could fail and
+deactivate parent class.
+
+Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Link: https://bugzilla.kernel.org/show_bug.cgi?id=109581
+---
+
+--- a/net/sched/sch_codel.c
++++ b/net/sched/sch_codel.c
+@@ -79,11 +79,17 @@ static struct sk_buff *codel_qdisc_deque
+ 
+       skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats, dequeue);
+ 
+-      /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
+-       * or HTB crashes. Defer it for next round.
++      /* If our qlen is 0 qdisc_tree_reduce_backlog() will deactivate
++       * parent class, dequeue in parent qdisc will do the same if we
++       * return skb. Temporary increment qlen if we have skb.
+        */
+-      if (q->stats.drop_count && sch->q.qlen) {
+-              qdisc_tree_reduce_backlog(sch, q->stats.drop_count, q->stats.drop_len);
++      if (q->stats.drop_count) {
++              if (skb)
++                      sch->q.qlen++;
++              qdisc_tree_reduce_backlog(sch, q->stats.drop_count,
++                                        q->stats.drop_len);
++              if (skb)
++                      sch->q.qlen--;
+               q->stats.drop_count = 0;
+               q->stats.drop_len = 0;
+       }
+--- a/net/sched/sch_fq_codel.c
++++ b/net/sched/sch_fq_codel.c
+@@ -311,6 +311,21 @@ begin:
+       flow->dropped += q->cstats.drop_count - prev_drop_count;
+       flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;
+ 
++      /* If our qlen is 0 qdisc_tree_reduce_backlog() will deactivate
++       * parent class, dequeue in parent qdisc will do the same if we
++       * return skb. Temporary increment qlen if we have skb.
++       */
++      if (q->cstats.drop_count) {
++              if (skb)
++                      sch->q.qlen++;
++              qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
++                                        q->cstats.drop_len);
++              if (skb)
++                      sch->q.qlen--;
++              q->cstats.drop_count = 0;
++              q->cstats.drop_len = 0;
++      }
++
+       if (!skb) {
+               /* force a pass through old_flows to prevent starvation */
+               if ((head == &q->new_flows) && !list_empty(&q->old_flows))
+@@ -321,15 +336,6 @@ begin:
+       }
+       qdisc_bstats_update(sch, skb);
+       flow->deficit -= qdisc_pkt_len(skb);
+-      /* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
+-       * or HTB crashes. Defer it for next round.
+-       */
+-      if (q->cstats.drop_count && sch->q.qlen) {
+-              qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
+-                                        q->cstats.drop_len);
+-              q->cstats.drop_count = 0;
+-              q->cstats.drop_len = 0;
+-      }
+       return skb;
+ }
+ 

diff --git a/target/linux/generic/patches-4.4/660-fq_codel_defaults.patch b/target/linux/generic/patches-4.4/660-fq_codel_defaults.patch
index 46fceffcf174f4b37a9a0aac9eba1d1e0505ef24..fbe900891c4faa1b7c6c63d0c03e435fa5d41ad6 100644 (file)
--- a/target/linux/generic/patches-4.4/660-fq_codel_defaults.patch
+++ b/target/linux/generic/patches-4.4/660-fq_codel_defaults.patch
@@ -1,6 +1,6 @@
 --- a/net/sched/sch_fq_codel.c
 +++ b/net/sched/sch_fq_codel.c
-@@ -471,7 +471,7 @@ static int fq_codel_init(struct Qdisc *s
+@@ -477,7 +477,7 @@ static int fq_codel_init(struct Qdisc *s
  
        sch->limit = 10*1024;
        q->flows_cnt = 1024;

diff --git a/target/linux/generic/patches-4.4/662-use_fq_codel_by_default.patch b/target/linux/generic/patches-4.4/662-use_fq_codel_by_default.patch
index 9d1962caa93f5543188809dff589750dce9d81f0..8d70b82350ee42ba7e1e1ab41b7d9555d70b719a 100644 (file)
--- a/target/linux/generic/patches-4.4/662-use_fq_codel_by_default.patch
+++ b/target/linux/generic/patches-4.4/662-use_fq_codel_by_default.patch
@@ -13,7 +13,7 @@
          device, it has to decide which ones to send first, which ones to
 --- a/net/sched/sch_fq_codel.c
 +++ b/net/sched/sch_fq_codel.c
-@@ -688,7 +688,7 @@ static const struct Qdisc_class_ops fq_c
+@@ -694,7 +694,7 @@ static const struct Qdisc_class_ops fq_c
        .walk           =       fq_codel_walk,
  };
  
@@ -22,7 +22,7 @@
        .cl_ops         =       &fq_codel_class_ops,
        .id             =       "fq_codel",
        .priv_size      =       sizeof(struct fq_codel_sched_data),
-@@ -704,6 +704,7 @@ static struct Qdisc_ops fq_codel_qdisc_o
+@@ -710,6 +710,7 @@ static struct Qdisc_ops fq_codel_qdisc_o
        .dump_stats =   fq_codel_dump_stats,
        .owner          =       THIS_MODULE,
  };