[NET]: Fix locking in shaper driver.

[linux-2.6.git] / drivers / net / shaper.c

/*
 *                      Simple traffic shaper for Linux NET3.
 *
 *      (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
 *                              http://www.redhat.com
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *      
 *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide 
 *      warranty for any of this software. This material is provided 
 *      "AS-IS" and at no charge.       
 *
 *      
 *      Algorithm:
 *
 *      Queue Frame:
 *              Compute time length of frame at regulated speed
 *              Add frame to queue at appropriate point
 *              Adjust time length computation for followup frames
 *              Any frame that falls outside of its boundaries is freed
 *
 *      We work to the following constants
 *
 *              SHAPER_QLEN     Maximum queued frames
 *              SHAPER_LATENCY  Bounding latency on a frame. Leaving this latency
 *                              window drops the frame. This stops us queueing 
 *                              frames for a long time and confusing a remote
 *                              host.
 *              SHAPER_MAXSLIP  Maximum time a priority frame may jump forward.
 *                              That bounds the penalty we will inflict on low
 *                              priority traffic.
 *              SHAPER_BURST    Time range we call "now" in order to reduce
 *                              system load. The more we make this the burstier
 *                              the behaviour, the better local performance you
 *                              get through packet clustering on routers and the
 *                              worse the remote end gets to judge rtts.
 *
 *      This is designed to handle lower speed links ( < 200K/second or so). We
 *      run off a 100-150Hz base clock typically. This gives us a resolution at
 *      200Kbit/second of about 2Kbit or 256 bytes. Above that our timer
 *      resolution may start to cause much more burstiness in the traffic. We
 *      could avoid a lot of that by calling kick_shaper() at the end of the 
 *      tied device transmissions. If you run above about 100K second you 
 *      may need to tune the supposed speed rate for the right values.
 *
 *      BUGS:
 *              Downing the interface under the shaper before the shaper
 *              will render your machine defunct. Don't for now shape over
 *              PPP or SLIP therefore!
 *              This will be fixed in BETA4
 *
 * Update History :
 *
 *              bh_atomic() SMP races fixes and rewritten the locking code to
 *              be SMP safe and irq-mask friendly.
 *              NOTE: we can't use start_bh_atomic() in kick_shaper()
 *              because it's going to be recalled from an irq handler,
 *              and synchronize_bh() is a nono if called from irq context.
 *                                              1999  Andrea Arcangeli
 *
 *              Device statistics (tx_pakets, tx_bytes,
 *              tx_drops: queue_over_time and collisions: max_queue_exceded)
 *                               1999/06/18 Jordi Murgo <savage@apostols.org>
 *
 *              Use skb->cb for private data.
 *                               2000/03 Andi Kleen
 */
 
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/if_shaper.h>

#include <net/dst.h>
#include <net/arp.h>

struct shaper_cb { 
        unsigned long   shapeclock;             /* Time it should go out */
        unsigned long   shapestamp;             /* Stamp for shaper    */
        __u32           shapelatency;           /* Latency on frame */
        __u32           shapelen;               /* Frame length in clocks */
        __u16           shapepend;              /* Pending */
}; 
#define SHAPERCB(skb) ((struct shaper_cb *) ((skb)->cb))

static int sh_debug;            /* Debug flag */

#define SHAPER_BANNER   "CymruNet Traffic Shaper BETA 0.04 for Linux 2.1\n"

static void shaper_kick(struct shaper *sh);

/*
 *      Compute clocks on a buffer
 */
  
static int shaper_clocks(struct shaper *shaper, struct sk_buff *skb)
{
        int t=skb->len/shaper->bytespertick;
        return t;
}

/*
 *      Set the speed of a shaper. We compute this in bytes per tick since
 *      thats how the machine wants to run. Quoted input is in bits per second
 *      as is traditional (note not BAUD). We assume 8 bit bytes. 
 */
  
static void shaper_setspeed(struct shaper *shaper, int bitspersec)
{
        shaper->bitspersec=bitspersec;
        shaper->bytespertick=(bitspersec/HZ)/8;
        if(!shaper->bytespertick)
                shaper->bytespertick++;
}

/*
 *      Throw a frame at a shaper.
 */
  

static int shaper_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct shaper *shaper = dev->priv;
        struct sk_buff *ptr;
   
        if (down_trylock(&shaper->sem))
                return -1;

        ptr=shaper->sendq.prev;
        
        /*
         *      Set up our packet details
         */
         
        SHAPERCB(skb)->shapelatency=0;
        SHAPERCB(skb)->shapeclock=shaper->recovery;
        if(time_before(SHAPERCB(skb)->shapeclock, jiffies))
                SHAPERCB(skb)->shapeclock=jiffies;
        skb->priority=0;        /* short term bug fix */
        SHAPERCB(skb)->shapestamp=jiffies;
        
        /*
         *      Time slots for this packet.
         */
         
        SHAPERCB(skb)->shapelen= shaper_clocks(shaper,skb);
        
#ifdef SHAPER_COMPLEX /* and broken.. */

        while(ptr && ptr!=(struct sk_buff *)&shaper->sendq)
        {
                if(ptr->pri<skb->pri 
                        && jiffies - SHAPERCB(ptr)->shapeclock < SHAPER_MAXSLIP)
                {
                        struct sk_buff *tmp=ptr->prev;

                        /*
                         *      It goes before us therefore we slip the length
                         *      of the new frame.
                         */

                        SHAPERCB(ptr)->shapeclock+=SHAPERCB(skb)->shapelen;
                        SHAPERCB(ptr)->shapelatency+=SHAPERCB(skb)->shapelen;

                        /*
                         *      The packet may have slipped so far back it
                         *      fell off.
                         */
                        if(SHAPERCB(ptr)->shapelatency > SHAPER_LATENCY)
                        {
                                skb_unlink(ptr);
                                dev_kfree_skb(ptr);
                        }
                        ptr=tmp;
                }
                else
                        break;
        }
        if(ptr==NULL || ptr==(struct sk_buff *)&shaper->sendq)
                skb_queue_head(&shaper->sendq,skb);
        else
        {
                struct sk_buff *tmp;
                /*
                 *      Set the packet clock out time according to the
                 *      frames ahead. Im sure a bit of thought could drop
                 *      this loop.
                 */
                for(tmp=skb_peek(&shaper->sendq); tmp!=NULL && tmp!=ptr; tmp=tmp->next)
                        SHAPERCB(skb)->shapeclock+=tmp->shapelen;
                skb_append(ptr,skb);
        }
#else
        {
                struct sk_buff *tmp;
                /*
                 *      Up our shape clock by the time pending on the queue
                 *      (Should keep this in the shaper as a variable..)
                 */
                for(tmp=skb_peek(&shaper->sendq); tmp!=NULL && 
                        tmp!=(struct sk_buff *)&shaper->sendq; tmp=tmp->next)
                        SHAPERCB(skb)->shapeclock+=SHAPERCB(tmp)->shapelen;
                /*
                 *      Queue over time. Spill packet.
                 */
                if(SHAPERCB(skb)->shapeclock-jiffies > SHAPER_LATENCY) {
                        dev_kfree_skb(skb);
                        shaper->stats.tx_dropped++;
                } else
                        skb_queue_tail(&shaper->sendq, skb);
        }
#endif  
        if(sh_debug)
                printk("Frame queued.\n");
        if(skb_queue_len(&shaper->sendq)>SHAPER_QLEN)
        {
                ptr=skb_dequeue(&shaper->sendq);
                dev_kfree_skb(ptr);
                shaper->stats.collisions++;
        }
        shaper_kick(shaper);
        up(&shaper->sem);
        return 0;
}

/*
 *      Transmit from a shaper
 */
 
static void shaper_queue_xmit(struct shaper *shaper, struct sk_buff *skb)
{
        struct sk_buff *newskb=skb_clone(skb, GFP_ATOMIC);
        if(sh_debug)
                printk("Kick frame on %p\n",newskb);
        if(newskb)
        {
                newskb->dev=shaper->dev;
                newskb->priority=2;
                if(sh_debug)
                        printk("Kick new frame to %s, %d\n",
                                shaper->dev->name,newskb->priority);
                dev_queue_xmit(newskb);

                shaper->stats.tx_bytes += skb->len;
                shaper->stats.tx_packets++;

                if(sh_debug)
                        printk("Kicked new frame out.\n");
                dev_kfree_skb(skb);
        }
}

/*
 *      Timer handler for shaping clock
 */
 
static void shaper_timer(unsigned long data)
{
        struct shaper *shaper = (struct shaper *)data;

        if (!down_trylock(&shaper->sem)) {
                shaper_kick(shaper);
                up(&shaper->sem);
        } else
                mod_timer(&shaper->timer, jiffies);
}

/*
 *      Kick a shaper queue and try and do something sensible with the 
 *      queue. 
 */

static void shaper_kick(struct shaper *shaper)
{
        struct sk_buff *skb;
        
        /*
         *      Walk the list (may be empty)
         */
         
        while((skb=skb_peek(&shaper->sendq))!=NULL)
        {
                /*
                 *      Each packet due to go out by now (within an error
                 *      of SHAPER_BURST) gets kicked onto the link 
                 */
                 
                if(sh_debug)
                        printk("Clock = %ld, jiffies = %ld\n", SHAPERCB(skb)->shapeclock, jiffies);
                if(time_before_eq(SHAPERCB(skb)->shapeclock, jiffies + SHAPER_BURST))
                {
                        /*
                         *      Pull the frame and get interrupts back on.
                         */
                         
                        skb_unlink(skb);
                        if (shaper->recovery < 
                            SHAPERCB(skb)->shapeclock + SHAPERCB(skb)->shapelen)
                                shaper->recovery = SHAPERCB(skb)->shapeclock + SHAPERCB(skb)->shapelen;
                        /*
                         *      Pass on to the physical target device via
                         *      our low level packet thrower.
                         */
                        
                        SHAPERCB(skb)->shapepend=0;
                        shaper_queue_xmit(shaper, skb); /* Fire */
                }
                else
                        break;
        }

        /*
         *      Next kick.
         */
         
        if(skb!=NULL)
                mod_timer(&shaper->timer, SHAPERCB(skb)->shapeclock);
}


/*
 *      Flush the shaper queues on a closedown
 */
 
static void shaper_flush(struct shaper *shaper)
{
        struct sk_buff *skb;

        down(&shaper->sem);
        while((skb=skb_dequeue(&shaper->sendq))!=NULL)
                dev_kfree_skb(skb);
        shaper_kick(shaper);
        up(&shaper->sem);
}

/*
 *      Bring the interface up. We just disallow this until a 
 *      bind.
 */

static int shaper_open(struct net_device *dev)
{
        struct shaper *shaper=dev->priv;
        
        /*
         *      Can't open until attached.
         *      Also can't open until speed is set, or we'll get
         *      a division by zero.
         */
         
        if(shaper->dev==NULL)
                return -ENODEV;
        if(shaper->bitspersec==0)
                return -EINVAL;
        return 0;
}

/*
 *      Closing a shaper flushes the queues.
 */
 
static int shaper_close(struct net_device *dev)
{
        struct shaper *shaper=dev->priv;
        shaper_flush(shaper);
        del_timer_sync(&shaper->timer);
        return 0;
}

/*
 *      Revectored calls. We alter the parameters and call the functions
 *      for our attached device. This enables us to bandwidth allocate after
 *      ARP and other resolutions and not before.
 */

static struct net_device_stats *shaper_get_stats(struct net_device *dev)
{
        struct shaper *sh=dev->priv;
        return &sh->stats;
}

static int shaper_header(struct sk_buff *skb, struct net_device *dev, 
        unsigned short type, void *daddr, void *saddr, unsigned len)
{
        struct shaper *sh=dev->priv;
        int v;
        if(sh_debug)
                printk("Shaper header\n");
        skb->dev=sh->dev;
        v=sh->hard_header(skb,sh->dev,type,daddr,saddr,len);
        skb->dev=dev;
        return v;
}

static int shaper_rebuild_header(struct sk_buff *skb)
{
        struct shaper *sh=skb->dev->priv;
        struct net_device *dev=skb->dev;
        int v;
        if(sh_debug)
                printk("Shaper rebuild header\n");
        skb->dev=sh->dev;
        v=sh->rebuild_header(skb);
        skb->dev=dev;
        return v;
}

#if 0
static int shaper_cache(struct neighbour *neigh, struct hh_cache *hh)
{
        struct shaper *sh=neigh->dev->priv;
        struct net_device *tmp;
        int ret;
        if(sh_debug)
                printk("Shaper header cache bind\n");
        tmp=neigh->dev;
        neigh->dev=sh->dev;
        ret=sh->hard_header_cache(neigh,hh);
        neigh->dev=tmp;
        return ret;
}

static void shaper_cache_update(struct hh_cache *hh, struct net_device *dev,
        unsigned char *haddr)
{
        struct shaper *sh=dev->priv;
        if(sh_debug)
                printk("Shaper cache update\n");
        sh->header_cache_update(hh, sh->dev, haddr);
}
#endif

#ifdef CONFIG_INET

static int shaper_neigh_setup(struct neighbour *n)
{
#ifdef CONFIG_INET
        if (n->nud_state == NUD_NONE) {
                n->ops = &arp_broken_ops;
                n->output = n->ops->output;
        }
#endif  
        return 0;
}

static int shaper_neigh_setup_dev(struct net_device *dev, struct neigh_parms *p)
{
#ifdef CONFIG_INET
        if (p->tbl->family == AF_INET) {
                p->neigh_setup = shaper_neigh_setup;
                p->ucast_probes = 0;
                p->mcast_probes = 0;
        }
#endif  
        return 0;
}

#else /* !(CONFIG_INET) */

static int shaper_neigh_setup_dev(struct net_device *dev, struct neigh_parms *p)
{
        return 0;
}

#endif

static int shaper_attach(struct net_device *shdev, struct shaper *sh, struct net_device *dev)
{
        sh->dev = dev;
        sh->hard_start_xmit=dev->hard_start_xmit;
        sh->get_stats=dev->get_stats;
        if(dev->hard_header)
        {
                sh->hard_header=dev->hard_header;
                shdev->hard_header = shaper_header;
        }
        else
                shdev->hard_header = NULL;
                
        if(dev->rebuild_header)
        {
                sh->rebuild_header      = dev->rebuild_header;
                shdev->rebuild_header   = shaper_rebuild_header;
        }
        else
                shdev->rebuild_header   = NULL;
        
#if 0
        if(dev->hard_header_cache)
        {
                sh->hard_header_cache   = dev->hard_header_cache;
                shdev->hard_header_cache= shaper_cache;
        }
        else
        {
                shdev->hard_header_cache= NULL;
        }
                        
        if(dev->header_cache_update)
        {
                sh->header_cache_update = dev->header_cache_update;
                shdev->header_cache_update = shaper_cache_update;
        }
        else
                shdev->header_cache_update= NULL;
#else
        shdev->header_cache_update = NULL;
        shdev->hard_header_cache = NULL;
#endif
        shdev->neigh_setup = shaper_neigh_setup_dev;
        
        shdev->hard_header_len=dev->hard_header_len;
        shdev->type=dev->type;
        shdev->addr_len=dev->addr_len;
        shdev->mtu=dev->mtu;
        sh->bitspersec=0;
        return 0;
}

static int shaper_ioctl(struct net_device *dev,  struct ifreq *ifr, int cmd)
{
        struct shaperconf *ss= (struct shaperconf *)&ifr->ifr_ifru;
        struct shaper *sh=dev->priv;
        
        if(ss->ss_cmd == SHAPER_SET_DEV || ss->ss_cmd == SHAPER_SET_SPEED)
        {
                if(!capable(CAP_NET_ADMIN))
                        return -EPERM;
        }
        
        switch(ss->ss_cmd)
        {
                case SHAPER_SET_DEV:
                {
                        struct net_device *them=__dev_get_by_name(ss->ss_name);
                        if(them==NULL)
                                return -ENODEV;
                        if(sh->dev)
                                return -EBUSY;
                        return shaper_attach(dev,dev->priv, them);
                }
                case SHAPER_GET_DEV:
                        if(sh->dev==NULL)
                                return -ENODEV;
                        strcpy(ss->ss_name, sh->dev->name);
                        return 0;
                case SHAPER_SET_SPEED:
                        shaper_setspeed(sh,ss->ss_speed);
                        return 0;
                case SHAPER_GET_SPEED:
                        ss->ss_speed=sh->bitspersec;
                        return 0;
                default:
                        return -EINVAL;
        }
}

static void shaper_init_priv(struct net_device *dev)
{
        struct shaper *sh = dev->priv;

        skb_queue_head_init(&sh->sendq);
        init_timer(&sh->timer);
        sh->timer.function=shaper_timer;
        sh->timer.data=(unsigned long)sh;
}

/*
 *      Add a shaper device to the system
 */
 
static void __init shaper_setup(struct net_device *dev)
{
        /*
         *      Set up the shaper.
         */

        SET_MODULE_OWNER(dev);

        shaper_init_priv(dev);

        dev->open               = shaper_open;
        dev->stop               = shaper_close;
        dev->hard_start_xmit    = shaper_start_xmit;
        dev->get_stats          = shaper_get_stats;
        dev->set_multicast_list = NULL;
        
        /*
         *      Intialise the packet queues
         */
         
        /*
         *      Handlers for when we attach to a device.
         */

        dev->hard_header        = shaper_header;
        dev->rebuild_header     = shaper_rebuild_header;
#if 0
        dev->hard_header_cache  = shaper_cache;
        dev->header_cache_update= shaper_cache_update;
#endif
        dev->neigh_setup        = shaper_neigh_setup_dev;
        dev->do_ioctl           = shaper_ioctl;
        dev->hard_header_len    = 0;
        dev->type               = ARPHRD_ETHER; /* initially */
        dev->set_mac_address    = NULL;
        dev->mtu                = 1500;
        dev->addr_len           = 0;
        dev->tx_queue_len       = 10;
        dev->flags              = 0;
}
 
static int shapers = 1;
#ifdef MODULE

module_param(shapers, int, 0);
MODULE_PARM_DESC(shapers, "Traffic shaper: maximum number of shapers");

#else /* MODULE */

static int __init set_num_shapers(char *str)
{
        shapers = simple_strtol(str, NULL, 0);
        return 1;
}

__setup("shapers=", set_num_shapers);

#endif /* MODULE */

static struct net_device **devs;

static unsigned int shapers_registered = 0;

static int __init shaper_init(void)
{
        int i;
        size_t alloc_size;
        struct net_device *dev;
        char name[IFNAMSIZ];

        if (shapers < 1)
                return -ENODEV;

        alloc_size = sizeof(*dev) * shapers;
        devs = kmalloc(alloc_size, GFP_KERNEL);
        if (!devs)
                return -ENOMEM;
        memset(devs, 0, alloc_size);

        for (i = 0; i < shapers; i++) {

                snprintf(name, IFNAMSIZ, "shaper%d", i);
                dev = alloc_netdev(sizeof(struct shaper), name,
                                   shaper_setup);
                if (!dev) 
                        break;

                if (register_netdev(dev)) {
                        free_netdev(dev);
                        break;
                }

                devs[i] = dev;
                shapers_registered++;
        }

        if (!shapers_registered) {
                kfree(devs);
                devs = NULL;
        }

        return (shapers_registered ? 0 : -ENODEV);
}

static void __exit shaper_exit (void)
{
        int i;

        for (i = 0; i < shapers_registered; i++) {
                if (devs[i]) {
                        unregister_netdev(devs[i]);
                        free_netdev(devs[i]);
                }
        }

        kfree(devs);
        devs = NULL;
}

module_init(shaper_init);
module_exit(shaper_exit);
MODULE_LICENSE("GPL");