kernel: merge a net-next fq_codel backlog handling fix

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@31813 3c298f89-4303-0410-b956-a3cf2f4a3e73

diff --git a/target/linux/generic/patches-3.3/046-fq_codel-qdisc-backlog.patch b/target/linux/generic/patches-3.3/046-fq_codel-qdisc-backlog.patch
new file mode 100644 (file)
index 0000000..5fc75a0
--- /dev/null
+++ b/target/linux/generic/patches-3.3/046-fq_codel-qdisc-backlog.patch
@@ -0,0 +1,133 @@
+From: Eric Dumazet <edumazet@google.com>
+
+codel_should_drop() logic allows a packet being not dropped if queue
+size is under max packet size.
+
+In fq_codel, we have two possible backlogs : The qdisc global one, and
+the flow local one.
+
+The meaningful one for codel_should_drop() should be the global backlog,
+not the per flow one, so that thin flows can have a non zero drop/mark
+probability.
+
+Signed-off-by: Eric Dumazet <edumazet@google.com>
+Cc: Dave Taht <dave.taht@bufferbloat.net>
+Cc: Kathleen Nichols <nichols@pollere.com>
+Cc: Van Jacobson <van@pollere.net>
+---
+ include/net/codel.h      |   15 +++++++--------
+ net/sched/sch_codel.c    |    4 ++--
+ net/sched/sch_fq_codel.c |    5 +++--
+ 3 files changed, 12 insertions(+), 12 deletions(-)
+
+diff --git a/include/net/codel.h b/include/net/codel.h
+index 7546517..550debf 100644
+--- a/include/net/codel.h
++++ b/include/net/codel.h
+@@ -205,7 +205,7 @@ static codel_time_t codel_control_law(codel_time_t t,
+ 
+ 
+ static bool codel_should_drop(const struct sk_buff *skb,
+-                            unsigned int *backlog,
++                            struct Qdisc *sch,
+                             struct codel_vars *vars,
+                             struct codel_params *params,
+                             struct codel_stats *stats,
+@@ -219,13 +219,13 @@ static bool codel_should_drop(const struct sk_buff *skb,
+       }
+ 
+       vars->ldelay = now - codel_get_enqueue_time(skb);
+-      *backlog -= qdisc_pkt_len(skb);
++      sch->qstats.backlog -= qdisc_pkt_len(skb);
+ 
+       if (unlikely(qdisc_pkt_len(skb) > stats->maxpacket))
+               stats->maxpacket = qdisc_pkt_len(skb);
+ 
+       if (codel_time_before(vars->ldelay, params->target) ||
+-          *backlog <= stats->maxpacket) {
++          sch->qstats.backlog <= stats->maxpacket) {
+               /* went below - stay below for at least interval */
+               vars->first_above_time = 0;
+               return false;
+@@ -249,8 +249,7 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
+                                    struct codel_params *params,
+                                    struct codel_vars *vars,
+                                    struct codel_stats *stats,
+-                                   codel_skb_dequeue_t dequeue_func,
+-                                   u32 *backlog)
++                                   codel_skb_dequeue_t dequeue_func)
+ {
+       struct sk_buff *skb = dequeue_func(vars, sch);
+       codel_time_t now;
+@@ -261,7 +260,7 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
+               return skb;
+       }
+       now = codel_get_time();
+-      drop = codel_should_drop(skb, backlog, vars, params, stats, now);
++      drop = codel_should_drop(skb, sch, vars, params, stats, now);
+       if (vars->dropping) {
+               if (!drop) {
+                       /* sojourn time below target - leave dropping state */
+@@ -292,7 +291,7 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
+                               qdisc_drop(skb, sch);
+                               stats->drop_count++;
+                               skb = dequeue_func(vars, sch);
+-                              if (!codel_should_drop(skb, backlog,
++                              if (!codel_should_drop(skb, sch,
+                                                      vars, params, stats, now)) {
+                                       /* leave dropping state */
+                                       vars->dropping = false;
+@@ -313,7 +312,7 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
+                       stats->drop_count++;
+ 
+                       skb = dequeue_func(vars, sch);
+-                      drop = codel_should_drop(skb, backlog, vars, params,
++                      drop = codel_should_drop(skb, sch, vars, params,
+                                                stats, now);
+               }
+               vars->dropping = true;
+diff --git a/net/sched/sch_codel.c b/net/sched/sch_codel.c
+index 213ef60..2f9ab17 100644
+--- a/net/sched/sch_codel.c
++++ b/net/sched/sch_codel.c
+@@ -77,8 +77,8 @@ static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch)
+       struct codel_sched_data *q = qdisc_priv(sch);
+       struct sk_buff *skb;
+ 
+-      skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats,
+-                          dequeue, &sch->qstats.backlog);
++      skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats, dequeue);
++
+       /* We cant call qdisc_tree_decrease_qlen() if our qlen is 0,
+        * or HTB crashes. Defer it for next round.
+        */
+diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
+index 337ff20..9fc1c62 100644
+--- a/net/sched/sch_fq_codel.c
++++ b/net/sched/sch_fq_codel.c
+@@ -217,13 +217,14 @@ static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch)
+  */
+ static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch)
+ {
++      struct fq_codel_sched_data *q = qdisc_priv(sch);
+       struct fq_codel_flow *flow;
+       struct sk_buff *skb = NULL;
+ 
+       flow = container_of(vars, struct fq_codel_flow, cvars);
+       if (flow->head) {
+               skb = dequeue_head(flow);
+-              sch->qstats.backlog -= qdisc_pkt_len(skb);
++              q->backlogs[flow - q->flows] -= qdisc_pkt_len(skb);
+               sch->q.qlen--;
+       }
+       return skb;
+@@ -256,7 +257,7 @@ begin:
+       prev_ecn_mark = q->cstats.ecn_mark;
+ 
+       skb = codel_dequeue(sch, &q->cparams, &flow->cvars, &q->cstats,
+-                          dequeue, &q->backlogs[flow - q->flows]);
++                          dequeue);
+ 
+       flow->dropped += q->cstats.drop_count - prev_drop_count;
+       flow->dropped += q->cstats.ecn_mark - prev_ecn_mark;
+