diff options
Diffstat (limited to 'target/linux/generic/patches-4.4/035-fq_codel-fix-NET_XMIT_CN-behavior.patch')
| -rw-r--r-- | target/linux/generic/patches-4.4/035-fq_codel-fix-NET_XMIT_CN-behavior.patch | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/target/linux/generic/patches-4.4/035-fq_codel-fix-NET_XMIT_CN-behavior.patch b/target/linux/generic/patches-4.4/035-fq_codel-fix-NET_XMIT_CN-behavior.patch new file mode 100644 index 0000000..a1902fe --- /dev/null +++ b/target/linux/generic/patches-4.4/035-fq_codel-fix-NET_XMIT_CN-behavior.patch @@ -0,0 +1,70 @@ +From: Eric Dumazet <edumazet@google.com> +Date: Sat, 4 Jun 2016 12:55:13 -0700 +Subject: [PATCH] fq_codel: fix NET_XMIT_CN behavior + +My prior attempt to fix the backlogs of parents failed. + +If we return NET_XMIT_CN, our parents wont increase their backlog, +so our qdisc_tree_reduce_backlog() should take this into account. + +v2: Florian Westphal pointed out that we could drop the packet, +so we need to save qdisc_pkt_len(skb) in a temp variable before +calling fq_codel_drop() + +Fixes: 9d18562a2278 ("fq_codel: add batch ability to fq_codel_drop()") +Fixes: 2ccccf5fb43f ("net_sched: update hierarchical backlog too") +Reported-by: Stas Nichiporovich <stasn77@gmail.com> +Signed-off-by: Eric Dumazet <edumazet@google.com> +Cc: WANG Cong <xiyou.wangcong@gmail.com> +Cc: Jamal Hadi Salim <jhs@mojatatu.com> +--- + +--- a/net/sched/sch_fq_codel.c ++++ b/net/sched/sch_fq_codel.c +@@ -197,6 +197,7 @@ static int fq_codel_enqueue(struct sk_bu + unsigned int idx, prev_backlog, prev_qlen; + struct fq_codel_flow *flow; + int uninitialized_var(ret); ++ unsigned int pkt_len; + bool memory_limited; + + idx = fq_codel_classify(skb, sch, &ret); +@@ -228,6 +229,8 @@ static int fq_codel_enqueue(struct sk_bu + prev_backlog = sch->qstats.backlog; + prev_qlen = sch->q.qlen; + ++ /* save this packet length as it might be dropped by fq_codel_drop() */ ++ pkt_len = qdisc_pkt_len(skb); + /* fq_codel_drop() is quite expensive, as it performs a linear search + * in q->backlogs[] to find a fat flow. + * So instead of dropping a single packet, drop half of its backlog +@@ -235,14 +238,23 @@ static int fq_codel_enqueue(struct sk_bu + */ + ret = fq_codel_drop(sch, q->drop_batch_size); + +- q->drop_overlimit += prev_qlen - sch->q.qlen; ++ prev_qlen -= sch->q.qlen; ++ prev_backlog -= sch->qstats.backlog; ++ q->drop_overlimit += prev_qlen; + if (memory_limited) +- q->drop_overmemory += prev_qlen - sch->q.qlen; +- /* As we dropped packet(s), better let upper stack know this */ +- qdisc_tree_reduce_backlog(sch, prev_qlen - sch->q.qlen, +- prev_backlog - sch->qstats.backlog); ++ q->drop_overmemory += prev_qlen; + +- return ret == idx ? NET_XMIT_CN : NET_XMIT_SUCCESS; ++ /* As we dropped packet(s), better let upper stack know this. ++ * If we dropped a packet for this flow, return NET_XMIT_CN, ++ * but in this case, our parents wont increase their backlogs. ++ */ ++ if (ret == idx) { ++ qdisc_tree_reduce_backlog(sch, prev_qlen - 1, ++ prev_backlog - pkt_len); ++ return NET_XMIT_CN; ++ } ++ qdisc_tree_reduce_backlog(sch, prev_qlen, prev_backlog); ++ return NET_XMIT_SUCCESS; + } + + /* This is the specific function called from codel_dequeue() |