kernel: merge a net-next fq_codel backlog handling fix

SVN-Revision: 31813

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;
+