[SFQ]: Remove artificial limitation for queue limit.

[karo-tx-linux.git] / net / sched / sch_sfq.c

diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index 3a23e30bc79e3689dc1f16fc9c16d0d76f820865..b542c875e154411cfaaf3d78abe443d9e5e4931d 100644 (file)
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -19,6 +19,7 @@
 #include <linux/init.h>
 #include <linux/ipv6.h>
 #include <linux/skbuff.h>
+#include <linux/jhash.h>
 #include <net/ip.h>
 #include <net/netlink.h>
 #include <net/pkt_sched.h>
@@ -95,7 +96,7 @@ struct sfq_sched_data
 
 /* Variables */
        struct timer_list perturb_timer;
-       int             perturbation;
+       u32             perturbation;
        sfq_index       tail;           /* Index of current slot in round */
        sfq_index       max_depth;      /* Maximal depth */
 
@@ -109,12 +110,7 @@ struct sfq_sched_data
 
 static __inline__ unsigned sfq_fold_hash(struct sfq_sched_data *q, u32 h, u32 h1)
 {
-       int pert = q->perturbation;
-
-       /* Have we any rotation primitives? If not, WHY? */
-       h ^= (h1<<pert) ^ (h1>>(0x1F - pert));
-       h ^= h>>10;
-       return h & 0x3FF;
+       return jhash_2words(h, h1, q->perturbation) & (SFQ_HASH_DIVISOR - 1);
 }
 
 static unsigned sfq_hash(struct sfq_sched_data *q, struct sk_buff *skb)
@@ -256,6 +252,13 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc* sch)
                q->ht[hash] = x = q->dep[SFQ_DEPTH].next;
                q->hash[x] = hash;
        }
+       /* If selected queue has length q->limit, this means that
+        * all another queues are empty and that we do simple tail drop,
+        * i.e. drop _this_ packet.
+        */
+       if (q->qs[x].qlen >= q->limit)
+               return qdisc_drop(skb, sch);
+
        sch->qstats.backlog += skb->len;
        __skb_queue_tail(&q->qs[x], skb);
        sfq_inc(q, x);
@@ -294,6 +297,19 @@ sfq_requeue(struct sk_buff *skb, struct Qdisc* sch)
        }
        sch->qstats.backlog += skb->len;
        __skb_queue_head(&q->qs[x], skb);
+       /* If selected queue has length q->limit+1, this means that
+        * all another queues are empty and we do simple tail drop.
+        * This packet is still requeued at head of queue, tail packet
+        * is dropped.
+        */
+       if (q->qs[x].qlen > q->limit) {
+               skb = q->qs[x].prev;
+               __skb_unlink(skb, &q->qs[x]);
+               sch->qstats.drops++;
+               sch->qstats.backlog -= skb->len;
+               kfree_skb(skb);
+               return NET_XMIT_CN;
+       }
        sfq_inc(q, x);
        if (q->qs[x].qlen == 1) {               /* The flow is new */
                if (q->tail == SFQ_DEPTH) {     /* It is the first flow */
@@ -370,12 +386,10 @@ static void sfq_perturbation(unsigned long arg)
        struct Qdisc *sch = (struct Qdisc*)arg;
        struct sfq_sched_data *q = qdisc_priv(sch);
 
-       q->perturbation = net_random()&0x1F;
+       get_random_bytes(&q->perturbation, 4);
 
-       if (q->perturb_period) {
-               q->perturb_timer.expires = jiffies + q->perturb_period;
-               add_timer(&q->perturb_timer);
-       }
+       if (q->perturb_period)
+               mod_timer(&q->perturb_timer, jiffies + q->perturb_period);
 }
 
 static int sfq_change(struct Qdisc *sch, struct rtattr *opt)
@@ -391,7 +405,7 @@ static int sfq_change(struct Qdisc *sch, struct rtattr *opt)
        q->quantum = ctl->quantum ? : psched_mtu(sch->dev);
        q->perturb_period = ctl->perturb_period*HZ;
        if (ctl->limit)
-               q->limit = min_t(u32, ctl->limit, SFQ_DEPTH - 2);
+               q->limit = min_t(u32, ctl->limit, SFQ_DEPTH - 1);
 
        qlen = sch->q.qlen;
        while (sch->q.qlen > q->limit)
@@ -400,8 +414,8 @@ static int sfq_change(struct Qdisc *sch, struct rtattr *opt)
 
        del_timer(&q->perturb_timer);
        if (q->perturb_period) {
-               q->perturb_timer.expires = jiffies + q->perturb_period;
-               add_timer(&q->perturb_timer);
+               mod_timer(&q->perturb_timer, jiffies + q->perturb_period);
+               get_random_bytes(&q->perturbation, 4);
        }
        sch_tree_unlock(sch);
        return 0;
@@ -423,12 +437,13 @@ static int sfq_init(struct Qdisc *sch, struct rtattr *opt)
                q->dep[i+SFQ_DEPTH].next = i+SFQ_DEPTH;
                q->dep[i+SFQ_DEPTH].prev = i+SFQ_DEPTH;
        }
-       q->limit = SFQ_DEPTH - 2;
+       q->limit = SFQ_DEPTH - 1;
        q->max_depth = 0;
        q->tail = SFQ_DEPTH;
        if (opt == NULL) {
                q->quantum = psched_mtu(sch->dev);
                q->perturb_period = 0;
+               get_random_bytes(&q->perturbation, 4);
        } else {
                int err = sfq_change(sch, opt);
                if (err)