static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
struct netem_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb2;
int ret;
pr_debug("netem_enqueue skb=%p @%lu\n", skb, jiffies);
/* Random packet drop 0 => none, ~0 => all */
if (q->loss && q->loss >= get_crandom(&q->loss_cor)) {
pr_debug("netem_enqueue: random loss\n");
sch->qstats.drops++;
kfree_skb(skb);
return 0; /* lie about loss so TCP doesn't know */
}
/* Random duplication */
if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor)
&& (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
pr_debug("netem_enqueue: dup %p\n", skb2);
if (delay_skb(sch, skb2)) {
sch->q.qlen++;
sch->bstats.bytes += skb2->len;
sch->bstats.packets++;
} else
sch->qstats.drops++;
}
/* If doing simple delay then gap == 0 so all packets
* go into the delayed holding queue
* otherwise if doing out of order only "1 out of gap"
* packets will be delayed.
*/
if (q->counter < q->gap) {
++q->counter;
ret = q->qdisc->enqueue(skb, q->qdisc);
} else {
q->counter = 0;
ret = delay_skb(sch, skb);
}
if (likely(ret == NET_XMIT_SUCCESS)) {
sch->q.qlen++;
sch->bstats.bytes += skb->len;
sch->bstats.packets++;
} else
sch->qstats.drops++;
return ret;
}
/* tabledist - return a pseudo-randomly distributed value with mean mu and
* std deviation sigma. Uses table lookup to approximate the desired
* distribution, and a uniformly-distributed pseudo-random source.
*/
static psched_tdiff_t tabledist(psched_tdiff_t mu, psched_tdiff_t sigma,
struct crndstate *state,
const struct disttable *dist)
{
psched_tdiff_t x;
long t;
u32 rnd;
if (sigma == 0)
return mu;
rnd = get_crandom(state);
/* default uniform distribution */
if (dist == NULL)
return (rnd % (2*sigma)) - sigma + mu;
t = dist->table[rnd % dist->size];
x = (sigma % NETEM_DIST_SCALE) * t;
if (x >= 0)
x += NETEM_DIST_SCALE/2;
else
x -= NETEM_DIST_SCALE/2;
return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
}
static bool loss_event(struct netem_sched_data *q)
{
switch (q->loss_model) {
case CLG_RANDOM:
/* Random packet drop 0 => none, ~0 => all */
return q->loss && q->loss >= get_crandom(&q->loss_cor);
case CLG_4_STATES:
/* 4state loss model algorithm (used also for GI model)
* Extracts a value from the markov 4 state loss generator,
* if it is 1 drops a packet and if needed writes the event in
* the kernel logs
*/
return loss_4state(q);
case CLG_GILB_ELL:
/* Gilbert-Elliot loss model algorithm
* Extracts a value from the Gilbert-Elliot loss generator,
* if it is 1 drops a packet and if needed writes the event in
* the kernel logs
*/
return loss_gilb_ell(q);
}
return false; /* not reached */
}
/* tabledist - return a pseudo-randomly distributed value with mean mu and
* std deviation sigma. Uses table lookup to approximate the desired
* distribution, and a uniformly-distributed pseudo-random source.
*/
static long tabledist(unsigned long mu, long sigma,
struct crndstate *state, const struct disttable *dist)
{
long t, x;
unsigned long rnd;
if (sigma == 0)
return mu;
rnd = get_crandom(state);
/* default uniform distribution */
if (dist == NULL)
return (rnd % (2*sigma)) - sigma + mu;
t = dist->table[rnd % dist->size];
x = (sigma % NETEM_DIST_SCALE) * t;
if (x >= 0)
x += NETEM_DIST_SCALE/2;
else
x -= NETEM_DIST_SCALE/2;
return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
}
/*
* Insert one skb into qdisc.
* Note: parent depends on return value to account for queue length.
* NET_XMIT_DROP: queue length didn't change.
* NET_XMIT_SUCCESS: one skb was queued.
*/
static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
struct netem_sched_data *q = qdisc_priv(sch);
/* We don't fill cb now as skb_unshare() may invalidate it */
struct netem_skb_cb *cb;
struct sk_buff *skb2;
int ret;
int count = 1;
pr_debug("netem_enqueue skb=%p\n", skb);
/* Random duplication */
if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
++count;
/* Random packet drop 0 => none, ~0 => all */
if (q->loss && q->loss >= get_crandom(&q->loss_cor))
--count;
if (count == 0) {
sch->qstats.drops++;
kfree_skb(skb);
return NET_XMIT_BYPASS;
}
skb_orphan(skb);
/*
* If we need to duplicate packet, then re-insert at top of the
* qdisc tree, since parent queuer expects that only one
* skb will be queued.
*/
if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
struct Qdisc *rootq = sch->dev->qdisc;
u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
q->duplicate = 0;
rootq->enqueue(skb2, rootq);
q->duplicate = dupsave;
}
/*
* Randomized packet corruption.
* Make copy if needed since we are modifying
* If packet is going to be hardware checksummed, then
* do it now in software before we mangle it.
*/
if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
if (!(skb = skb_unshare(skb, GFP_ATOMIC))
|| (skb->ip_summed == CHECKSUM_PARTIAL
&& skb_checksum_help(skb))) {
sch->qstats.drops++;
return NET_XMIT_DROP;
}
skb->data[net_random() % skb_headlen(skb)] ^= 1<<(net_random() % 8);
}
cb = (struct netem_skb_cb *)skb->cb;
if (q->gap == 0 /* not doing reordering */
|| q->counter < q->gap /* inside last reordering gap */
|| q->reorder < get_crandom(&q->reorder_cor)) {
psched_time_t now;
psched_tdiff_t delay;
delay = tabledist(q->latency, q->jitter,
&q->delay_cor, q->delay_dist);
now = psched_get_time();
cb->time_to_send = now + delay;
++q->counter;
ret = q->qdisc->enqueue(skb, q->qdisc);
} else {
/*
* Do re-ordering by putting one out of N packets at the front
* of the queue.
*/
cb->time_to_send = psched_get_time();
q->counter = 0;
ret = q->qdisc->ops->requeue(skb, q->qdisc);
}
if (likely(ret == NET_XMIT_SUCCESS)) {
sch->q.qlen++;
sch->bstats.bytes += skb->len;
sch->bstats.packets++;
} else
sch->qstats.drops++;
pr_debug("netem: enqueue ret %d\n", ret);
return ret;
}
/*
* Insert one skb into qdisc.
* Note: parent depends on return value to account for queue length.
* NET_XMIT_DROP: queue length didn't change.
* NET_XMIT_SUCCESS: one skb was queued.
*/
static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
struct netem_sched_data *q = qdisc_priv(sch);
/* We don't fill cb now as skb_unshare() may invalidate it */
struct netem_skb_cb *cb;
struct sk_buff *skb2;
int count = 1;
/* Random duplication */
if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
++count;
/* Drop packet? */
if (loss_event(q))
--count;
if (count == 0) {
sch->qstats.drops++;
kfree_skb(skb);
return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
}
skb_orphan(skb);
/*
* If we need to duplicate packet, then re-insert at top of the
* qdisc tree, since parent queuer expects that only one
* skb will be queued.
*/
if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
struct Qdisc *rootq = qdisc_root(sch);
u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
q->duplicate = 0;
qdisc_enqueue_root(skb2, rootq);
q->duplicate = dupsave;
}
/*
* Randomized packet corruption.
* Make copy if needed since we are modifying
* If packet is going to be hardware checksummed, then
* do it now in software before we mangle it.
*/
if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
if (!(skb = skb_unshare(skb, GFP_ATOMIC)) ||
(skb->ip_summed == CHECKSUM_PARTIAL &&
skb_checksum_help(skb)))
return qdisc_drop(skb, sch);
skb->data[net_random() % skb_headlen(skb)] ^= 1<<(net_random() % 8);
}
if (unlikely(skb_queue_len(&sch->q) >= sch->limit))
return qdisc_reshape_fail(skb, sch);
sch->qstats.backlog += qdisc_pkt_len(skb);
cb = netem_skb_cb(skb);
if (q->gap == 0 || /* not doing reordering */
q->counter < q->gap - 1 || /* inside last reordering gap */
q->reorder < get_crandom(&q->reorder_cor)) {
psched_time_t now;
psched_tdiff_t delay;
delay = tabledist(q->latency, q->jitter,
&q->delay_cor, q->delay_dist);
now = psched_get_time();
if (q->rate) {
struct sk_buff_head *list = &sch->q;
delay += packet_len_2_sched_time(skb->len, q);
if (!skb_queue_empty(list)) {
/*
* Last packet in queue is reference point (now).
* First packet in queue is already in flight,
* calculate this time bonus and substract
* from delay.
*/
delay -= now - netem_skb_cb(skb_peek(list))->time_to_send;
now = netem_skb_cb(skb_peek_tail(list))->time_to_send;
}
}
cb->time_to_send = now + delay;
++q->counter;
tfifo_enqueue(skb, sch);
} else {
/*
* Do re-ordering by putting one out of N packets at the front
* of the queue.
*/
cb->time_to_send = psched_get_time();
q->counter = 0;
__skb_queue_head(&sch->q, skb);
sch->qstats.requeues++;
}
return NET_XMIT_SUCCESS;
}
