![Stephen Hemminger](/assets/img/avatar_default.png)
Here is a new feature for netem in 2.6.16. It adds the ability to randomly corrupt packets with netem. A version was done by Hagen Paul Pfeifer, but I redid it to handle the cases of backwards compatibility with netlink interface and presence of hardware checksum offload. It is useful for testing hardware offload in devices. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
752 lines
18 KiB
C
752 lines
18 KiB
C
/*
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* net/sched/sch_netem.c Network emulator
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Many of the algorithms and ideas for this came from
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* NIST Net which is not copyrighted.
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*
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* Authors: Stephen Hemminger <shemminger@osdl.org>
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* Catalin(ux aka Dino) BOIE <catab at umbrella dot ro>
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/bitops.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <linux/rtnetlink.h>
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#include <net/pkt_sched.h>
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#define VERSION "1.2"
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/* Network Emulation Queuing algorithm.
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====================================
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Sources: [1] Mark Carson, Darrin Santay, "NIST Net - A Linux-based
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Network Emulation Tool
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[2] Luigi Rizzo, DummyNet for FreeBSD
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----------------------------------------------------------------
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This started out as a simple way to delay outgoing packets to
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test TCP but has grown to include most of the functionality
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of a full blown network emulator like NISTnet. It can delay
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packets and add random jitter (and correlation). The random
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distribution can be loaded from a table as well to provide
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normal, Pareto, or experimental curves. Packet loss,
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duplication, and reordering can also be emulated.
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This qdisc does not do classification that can be handled in
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layering other disciplines. It does not need to do bandwidth
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control either since that can be handled by using token
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bucket or other rate control.
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The simulator is limited by the Linux timer resolution
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and will create packet bursts on the HZ boundary (1ms).
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*/
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struct netem_sched_data {
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struct Qdisc *qdisc;
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struct timer_list timer;
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u32 latency;
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u32 loss;
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u32 limit;
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u32 counter;
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u32 gap;
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u32 jitter;
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u32 duplicate;
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u32 reorder;
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u32 corrupt;
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struct crndstate {
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unsigned long last;
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unsigned long rho;
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} delay_cor, loss_cor, dup_cor, reorder_cor, corrupt_cor;
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struct disttable {
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u32 size;
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s16 table[0];
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} *delay_dist;
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};
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/* Time stamp put into socket buffer control block */
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struct netem_skb_cb {
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psched_time_t time_to_send;
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};
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/* init_crandom - initialize correlated random number generator
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* Use entropy source for initial seed.
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*/
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static void init_crandom(struct crndstate *state, unsigned long rho)
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{
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state->rho = rho;
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state->last = net_random();
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}
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/* get_crandom - correlated random number generator
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* Next number depends on last value.
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* rho is scaled to avoid floating point.
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*/
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static unsigned long get_crandom(struct crndstate *state)
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{
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u64 value, rho;
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unsigned long answer;
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if (state->rho == 0) /* no correllation */
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return net_random();
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value = net_random();
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rho = (u64)state->rho + 1;
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answer = (value * ((1ull<<32) - rho) + state->last * rho) >> 32;
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state->last = answer;
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return answer;
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}
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/* tabledist - return a pseudo-randomly distributed value with mean mu and
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* std deviation sigma. Uses table lookup to approximate the desired
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* distribution, and a uniformly-distributed pseudo-random source.
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*/
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static long tabledist(unsigned long mu, long sigma,
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struct crndstate *state, const struct disttable *dist)
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{
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long t, x;
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unsigned long rnd;
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if (sigma == 0)
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return mu;
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rnd = get_crandom(state);
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/* default uniform distribution */
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if (dist == NULL)
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return (rnd % (2*sigma)) - sigma + mu;
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t = dist->table[rnd % dist->size];
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x = (sigma % NETEM_DIST_SCALE) * t;
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if (x >= 0)
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x += NETEM_DIST_SCALE/2;
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else
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x -= NETEM_DIST_SCALE/2;
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return x / NETEM_DIST_SCALE + (sigma / NETEM_DIST_SCALE) * t + mu;
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}
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/*
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* Insert one skb into qdisc.
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* Note: parent depends on return value to account for queue length.
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* NET_XMIT_DROP: queue length didn't change.
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* NET_XMIT_SUCCESS: one skb was queued.
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*/
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static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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struct netem_skb_cb *cb = (struct netem_skb_cb *)skb->cb;
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struct sk_buff *skb2;
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int ret;
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int count = 1;
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pr_debug("netem_enqueue skb=%p\n", skb);
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/* Random duplication */
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if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor))
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++count;
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/* Random packet drop 0 => none, ~0 => all */
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if (q->loss && q->loss >= get_crandom(&q->loss_cor))
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--count;
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if (count == 0) {
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sch->qstats.drops++;
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kfree_skb(skb);
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return NET_XMIT_DROP;
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}
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/*
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* If we need to duplicate packet, then re-insert at top of the
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* qdisc tree, since parent queuer expects that only one
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* skb will be queued.
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*/
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if (count > 1 && (skb2 = skb_clone(skb, GFP_ATOMIC)) != NULL) {
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struct Qdisc *rootq = sch->dev->qdisc;
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u32 dupsave = q->duplicate; /* prevent duplicating a dup... */
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q->duplicate = 0;
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rootq->enqueue(skb2, rootq);
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q->duplicate = dupsave;
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}
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/*
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* Randomized packet corruption.
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* Make copy if needed since we are modifying
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* If packet is going to be hardware checksummed, then
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* do it now in software before we mangle it.
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*/
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if (q->corrupt && q->corrupt >= get_crandom(&q->corrupt_cor)) {
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if (!(skb = skb_unshare(skb, GFP_ATOMIC))
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|| (skb->ip_summed == CHECKSUM_HW
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&& skb_checksum_help(skb, 0))) {
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sch->qstats.drops++;
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return NET_XMIT_DROP;
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}
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skb->data[net_random() % skb_headlen(skb)] ^= 1<<(net_random() % 8);
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}
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if (q->gap == 0 /* not doing reordering */
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|| q->counter < q->gap /* inside last reordering gap */
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|| q->reorder < get_crandom(&q->reorder_cor)) {
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psched_time_t now;
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psched_tdiff_t delay;
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delay = tabledist(q->latency, q->jitter,
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&q->delay_cor, q->delay_dist);
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PSCHED_GET_TIME(now);
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PSCHED_TADD2(now, delay, cb->time_to_send);
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++q->counter;
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ret = q->qdisc->enqueue(skb, q->qdisc);
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} else {
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/*
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* Do re-ordering by putting one out of N packets at the front
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* of the queue.
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*/
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PSCHED_GET_TIME(cb->time_to_send);
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q->counter = 0;
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ret = q->qdisc->ops->requeue(skb, q->qdisc);
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}
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if (likely(ret == NET_XMIT_SUCCESS)) {
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sch->q.qlen++;
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sch->bstats.bytes += skb->len;
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sch->bstats.packets++;
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} else
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sch->qstats.drops++;
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pr_debug("netem: enqueue ret %d\n", ret);
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return ret;
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}
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/* Requeue packets but don't change time stamp */
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static int netem_requeue(struct sk_buff *skb, struct Qdisc *sch)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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int ret;
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if ((ret = q->qdisc->ops->requeue(skb, q->qdisc)) == 0) {
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sch->q.qlen++;
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sch->qstats.requeues++;
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}
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return ret;
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}
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static unsigned int netem_drop(struct Qdisc* sch)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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unsigned int len;
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if ((len = q->qdisc->ops->drop(q->qdisc)) != 0) {
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sch->q.qlen--;
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sch->qstats.drops++;
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}
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return len;
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}
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static struct sk_buff *netem_dequeue(struct Qdisc *sch)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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struct sk_buff *skb;
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skb = q->qdisc->dequeue(q->qdisc);
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if (skb) {
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const struct netem_skb_cb *cb
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= (const struct netem_skb_cb *)skb->cb;
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psched_time_t now;
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/* if more time remaining? */
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PSCHED_GET_TIME(now);
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if (PSCHED_TLESS(cb->time_to_send, now)) {
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pr_debug("netem_dequeue: return skb=%p\n", skb);
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sch->q.qlen--;
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sch->flags &= ~TCQ_F_THROTTLED;
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return skb;
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} else {
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psched_tdiff_t delay = PSCHED_TDIFF(cb->time_to_send, now);
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if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) {
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sch->qstats.drops++;
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/* After this qlen is confused */
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printk(KERN_ERR "netem: queue discpline %s could not requeue\n",
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q->qdisc->ops->id);
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sch->q.qlen--;
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}
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mod_timer(&q->timer, jiffies + PSCHED_US2JIFFIE(delay));
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sch->flags |= TCQ_F_THROTTLED;
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}
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}
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return NULL;
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}
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static void netem_watchdog(unsigned long arg)
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{
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struct Qdisc *sch = (struct Qdisc *)arg;
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pr_debug("netem_watchdog qlen=%d\n", sch->q.qlen);
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sch->flags &= ~TCQ_F_THROTTLED;
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netif_schedule(sch->dev);
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}
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static void netem_reset(struct Qdisc *sch)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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qdisc_reset(q->qdisc);
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sch->q.qlen = 0;
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sch->flags &= ~TCQ_F_THROTTLED;
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del_timer_sync(&q->timer);
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}
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/* Pass size change message down to embedded FIFO */
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static int set_fifo_limit(struct Qdisc *q, int limit)
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{
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struct rtattr *rta;
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int ret = -ENOMEM;
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/* Hack to avoid sending change message to non-FIFO */
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if (strncmp(q->ops->id + 1, "fifo", 4) != 0)
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return 0;
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rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
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if (rta) {
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rta->rta_type = RTM_NEWQDISC;
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rta->rta_len = RTA_LENGTH(sizeof(struct tc_fifo_qopt));
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((struct tc_fifo_qopt *)RTA_DATA(rta))->limit = limit;
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ret = q->ops->change(q, rta);
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kfree(rta);
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}
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return ret;
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}
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/*
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* Distribution data is a variable size payload containing
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* signed 16 bit values.
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*/
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static int get_dist_table(struct Qdisc *sch, const struct rtattr *attr)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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unsigned long n = RTA_PAYLOAD(attr)/sizeof(__s16);
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const __s16 *data = RTA_DATA(attr);
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struct disttable *d;
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int i;
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if (n > 65536)
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return -EINVAL;
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d = kmalloc(sizeof(*d) + n*sizeof(d->table[0]), GFP_KERNEL);
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if (!d)
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return -ENOMEM;
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d->size = n;
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for (i = 0; i < n; i++)
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d->table[i] = data[i];
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spin_lock_bh(&sch->dev->queue_lock);
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d = xchg(&q->delay_dist, d);
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spin_unlock_bh(&sch->dev->queue_lock);
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kfree(d);
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return 0;
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}
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static int get_correlation(struct Qdisc *sch, const struct rtattr *attr)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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const struct tc_netem_corr *c = RTA_DATA(attr);
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if (RTA_PAYLOAD(attr) != sizeof(*c))
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return -EINVAL;
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init_crandom(&q->delay_cor, c->delay_corr);
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init_crandom(&q->loss_cor, c->loss_corr);
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init_crandom(&q->dup_cor, c->dup_corr);
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return 0;
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}
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static int get_reorder(struct Qdisc *sch, const struct rtattr *attr)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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const struct tc_netem_reorder *r = RTA_DATA(attr);
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if (RTA_PAYLOAD(attr) != sizeof(*r))
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return -EINVAL;
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q->reorder = r->probability;
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init_crandom(&q->reorder_cor, r->correlation);
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return 0;
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}
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static int get_corrupt(struct Qdisc *sch, const struct rtattr *attr)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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const struct tc_netem_corrupt *r = RTA_DATA(attr);
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if (RTA_PAYLOAD(attr) != sizeof(*r))
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return -EINVAL;
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q->corrupt = r->probability;
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init_crandom(&q->corrupt_cor, r->correlation);
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return 0;
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}
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/* Parse netlink message to set options */
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static int netem_change(struct Qdisc *sch, struct rtattr *opt)
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{
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struct netem_sched_data *q = qdisc_priv(sch);
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struct tc_netem_qopt *qopt;
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int ret;
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if (opt == NULL || RTA_PAYLOAD(opt) < sizeof(*qopt))
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return -EINVAL;
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qopt = RTA_DATA(opt);
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ret = set_fifo_limit(q->qdisc, qopt->limit);
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if (ret) {
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pr_debug("netem: can't set fifo limit\n");
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return ret;
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}
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q->latency = qopt->latency;
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q->jitter = qopt->jitter;
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q->limit = qopt->limit;
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q->gap = qopt->gap;
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q->counter = 0;
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q->loss = qopt->loss;
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q->duplicate = qopt->duplicate;
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/* for compatiablity with earlier versions.
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* if gap is set, need to assume 100% probablity
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*/
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q->reorder = ~0;
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/* Handle nested options after initial queue options.
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* Should have put all options in nested format but too late now.
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*/
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if (RTA_PAYLOAD(opt) > sizeof(*qopt)) {
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struct rtattr *tb[TCA_NETEM_MAX];
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if (rtattr_parse(tb, TCA_NETEM_MAX,
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RTA_DATA(opt) + sizeof(*qopt),
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RTA_PAYLOAD(opt) - sizeof(*qopt)))
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return -EINVAL;
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if (tb[TCA_NETEM_CORR-1]) {
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ret = get_correlation(sch, tb[TCA_NETEM_CORR-1]);
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if (ret)
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return ret;
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}
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if (tb[TCA_NETEM_DELAY_DIST-1]) {
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ret = get_dist_table(sch, tb[TCA_NETEM_DELAY_DIST-1]);
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if (ret)
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return ret;
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}
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if (tb[TCA_NETEM_REORDER-1]) {
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ret = get_reorder(sch, tb[TCA_NETEM_REORDER-1]);
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if (ret)
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return ret;
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}
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if (tb[TCA_NETEM_CORRUPT-1]) {
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ret = get_corrupt(sch, tb[TCA_NETEM_CORRUPT-1]);
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if (ret)
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return ret;
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}
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}
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return 0;
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}
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/*
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* Special case version of FIFO queue for use by netem.
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* It queues in order based on timestamps in skb's
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*/
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struct fifo_sched_data {
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u32 limit;
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};
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static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
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{
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struct fifo_sched_data *q = qdisc_priv(sch);
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struct sk_buff_head *list = &sch->q;
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const struct netem_skb_cb *ncb
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= (const struct netem_skb_cb *)nskb->cb;
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struct sk_buff *skb;
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if (likely(skb_queue_len(list) < q->limit)) {
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skb_queue_reverse_walk(list, skb) {
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const struct netem_skb_cb *cb
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= (const struct netem_skb_cb *)skb->cb;
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if (!PSCHED_TLESS(ncb->time_to_send, cb->time_to_send))
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break;
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}
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__skb_queue_after(list, skb, nskb);
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sch->qstats.backlog += nskb->len;
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sch->bstats.bytes += nskb->len;
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sch->bstats.packets++;
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return NET_XMIT_SUCCESS;
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}
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return qdisc_drop(nskb, sch);
|
|
}
|
|
|
|
static int tfifo_init(struct Qdisc *sch, struct rtattr *opt)
|
|
{
|
|
struct fifo_sched_data *q = qdisc_priv(sch);
|
|
|
|
if (opt) {
|
|
struct tc_fifo_qopt *ctl = RTA_DATA(opt);
|
|
if (RTA_PAYLOAD(opt) < sizeof(*ctl))
|
|
return -EINVAL;
|
|
|
|
q->limit = ctl->limit;
|
|
} else
|
|
q->limit = max_t(u32, sch->dev->tx_queue_len, 1);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int tfifo_dump(struct Qdisc *sch, struct sk_buff *skb)
|
|
{
|
|
struct fifo_sched_data *q = qdisc_priv(sch);
|
|
struct tc_fifo_qopt opt = { .limit = q->limit };
|
|
|
|
RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
|
|
return skb->len;
|
|
|
|
rtattr_failure:
|
|
return -1;
|
|
}
|
|
|
|
static struct Qdisc_ops tfifo_qdisc_ops = {
|
|
.id = "tfifo",
|
|
.priv_size = sizeof(struct fifo_sched_data),
|
|
.enqueue = tfifo_enqueue,
|
|
.dequeue = qdisc_dequeue_head,
|
|
.requeue = qdisc_requeue,
|
|
.drop = qdisc_queue_drop,
|
|
.init = tfifo_init,
|
|
.reset = qdisc_reset_queue,
|
|
.change = tfifo_init,
|
|
.dump = tfifo_dump,
|
|
};
|
|
|
|
static int netem_init(struct Qdisc *sch, struct rtattr *opt)
|
|
{
|
|
struct netem_sched_data *q = qdisc_priv(sch);
|
|
int ret;
|
|
|
|
if (!opt)
|
|
return -EINVAL;
|
|
|
|
init_timer(&q->timer);
|
|
q->timer.function = netem_watchdog;
|
|
q->timer.data = (unsigned long) sch;
|
|
|
|
q->qdisc = qdisc_create_dflt(sch->dev, &tfifo_qdisc_ops);
|
|
if (!q->qdisc) {
|
|
pr_debug("netem: qdisc create failed\n");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
ret = netem_change(sch, opt);
|
|
if (ret) {
|
|
pr_debug("netem: change failed\n");
|
|
qdisc_destroy(q->qdisc);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static void netem_destroy(struct Qdisc *sch)
|
|
{
|
|
struct netem_sched_data *q = qdisc_priv(sch);
|
|
|
|
del_timer_sync(&q->timer);
|
|
qdisc_destroy(q->qdisc);
|
|
kfree(q->delay_dist);
|
|
}
|
|
|
|
static int netem_dump(struct Qdisc *sch, struct sk_buff *skb)
|
|
{
|
|
const struct netem_sched_data *q = qdisc_priv(sch);
|
|
unsigned char *b = skb->tail;
|
|
struct rtattr *rta = (struct rtattr *) b;
|
|
struct tc_netem_qopt qopt;
|
|
struct tc_netem_corr cor;
|
|
struct tc_netem_reorder reorder;
|
|
struct tc_netem_corrupt corrupt;
|
|
|
|
qopt.latency = q->latency;
|
|
qopt.jitter = q->jitter;
|
|
qopt.limit = q->limit;
|
|
qopt.loss = q->loss;
|
|
qopt.gap = q->gap;
|
|
qopt.duplicate = q->duplicate;
|
|
RTA_PUT(skb, TCA_OPTIONS, sizeof(qopt), &qopt);
|
|
|
|
cor.delay_corr = q->delay_cor.rho;
|
|
cor.loss_corr = q->loss_cor.rho;
|
|
cor.dup_corr = q->dup_cor.rho;
|
|
RTA_PUT(skb, TCA_NETEM_CORR, sizeof(cor), &cor);
|
|
|
|
reorder.probability = q->reorder;
|
|
reorder.correlation = q->reorder_cor.rho;
|
|
RTA_PUT(skb, TCA_NETEM_REORDER, sizeof(reorder), &reorder);
|
|
|
|
corrupt.probability = q->corrupt;
|
|
corrupt.correlation = q->corrupt_cor.rho;
|
|
RTA_PUT(skb, TCA_NETEM_CORRUPT, sizeof(corrupt), &corrupt);
|
|
|
|
rta->rta_len = skb->tail - b;
|
|
|
|
return skb->len;
|
|
|
|
rtattr_failure:
|
|
skb_trim(skb, b - skb->data);
|
|
return -1;
|
|
}
|
|
|
|
static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
|
|
struct sk_buff *skb, struct tcmsg *tcm)
|
|
{
|
|
struct netem_sched_data *q = qdisc_priv(sch);
|
|
|
|
if (cl != 1) /* only one class */
|
|
return -ENOENT;
|
|
|
|
tcm->tcm_handle |= TC_H_MIN(1);
|
|
tcm->tcm_info = q->qdisc->handle;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
|
|
struct Qdisc **old)
|
|
{
|
|
struct netem_sched_data *q = qdisc_priv(sch);
|
|
|
|
if (new == NULL)
|
|
new = &noop_qdisc;
|
|
|
|
sch_tree_lock(sch);
|
|
*old = xchg(&q->qdisc, new);
|
|
qdisc_reset(*old);
|
|
sch->q.qlen = 0;
|
|
sch_tree_unlock(sch);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct Qdisc *netem_leaf(struct Qdisc *sch, unsigned long arg)
|
|
{
|
|
struct netem_sched_data *q = qdisc_priv(sch);
|
|
return q->qdisc;
|
|
}
|
|
|
|
static unsigned long netem_get(struct Qdisc *sch, u32 classid)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
static void netem_put(struct Qdisc *sch, unsigned long arg)
|
|
{
|
|
}
|
|
|
|
static int netem_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
|
|
struct rtattr **tca, unsigned long *arg)
|
|
{
|
|
return -ENOSYS;
|
|
}
|
|
|
|
static int netem_delete(struct Qdisc *sch, unsigned long arg)
|
|
{
|
|
return -ENOSYS;
|
|
}
|
|
|
|
static void netem_walk(struct Qdisc *sch, struct qdisc_walker *walker)
|
|
{
|
|
if (!walker->stop) {
|
|
if (walker->count >= walker->skip)
|
|
if (walker->fn(sch, 1, walker) < 0) {
|
|
walker->stop = 1;
|
|
return;
|
|
}
|
|
walker->count++;
|
|
}
|
|
}
|
|
|
|
static struct tcf_proto **netem_find_tcf(struct Qdisc *sch, unsigned long cl)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
static struct Qdisc_class_ops netem_class_ops = {
|
|
.graft = netem_graft,
|
|
.leaf = netem_leaf,
|
|
.get = netem_get,
|
|
.put = netem_put,
|
|
.change = netem_change_class,
|
|
.delete = netem_delete,
|
|
.walk = netem_walk,
|
|
.tcf_chain = netem_find_tcf,
|
|
.dump = netem_dump_class,
|
|
};
|
|
|
|
static struct Qdisc_ops netem_qdisc_ops = {
|
|
.id = "netem",
|
|
.cl_ops = &netem_class_ops,
|
|
.priv_size = sizeof(struct netem_sched_data),
|
|
.enqueue = netem_enqueue,
|
|
.dequeue = netem_dequeue,
|
|
.requeue = netem_requeue,
|
|
.drop = netem_drop,
|
|
.init = netem_init,
|
|
.reset = netem_reset,
|
|
.destroy = netem_destroy,
|
|
.change = netem_change,
|
|
.dump = netem_dump,
|
|
.owner = THIS_MODULE,
|
|
};
|
|
|
|
|
|
static int __init netem_module_init(void)
|
|
{
|
|
pr_info("netem: version " VERSION "\n");
|
|
return register_qdisc(&netem_qdisc_ops);
|
|
}
|
|
static void __exit netem_module_exit(void)
|
|
{
|
|
unregister_qdisc(&netem_qdisc_ops);
|
|
}
|
|
module_init(netem_module_init)
|
|
module_exit(netem_module_exit)
|
|
MODULE_LICENSE("GPL");
|