Repost, left dummy alone - new device called IFB (Intermediate
Functional Block) taking feedback from Patrick and Andi. 


> On Wed, 2005-28-12 at 10:40 -0500, jamal wrote:
> Dave,
> This is intended for 2.6.16 since it is a new feature.
> 
> To everyone who has contacted me over the last few months, I apologize
> for sitting on this for so long (Ive tried to CC a few). I tend to have
> more time at year end - and so here it is. This patch does not support
> feature #3 in the thread of discussion at:
> http://marc.theaimsgroup.com/?t=110712330700001&r=2&w=2
> The reason infact i was sitting on it is to try and get #3 out first.
> That could come later;
> 
> while this is for 2.6.16 it should apply cleanly to any
> of the 2.6.15-rcx trees (infact thats where i tested it). I am going to
> send an iproute2 patch that is only documentation on usage etc.

The note above still applies.

Anyone wishing to compile this as a module and doesnt know how to email
me. i.e this way you dont have to patch your kernel.

cheers,
jamal
A new device to do intermidiate functional block in a system shared manner.
To use the new functionality, you need to turn on qos/classifier actions.

The new functionality can be grouped as:
1) qdiscs/policies that are per device as opposed to system wide.
This now allows for sharing.

2) Allows for queueing incoming traffic for shaping instead of
dropping. 

Packets are redirected to this device using tc/action mirred redirect
construct. If they are sent to it by plain routing instead 
then they will merely be dropped and the stats would indicate that.

Signed-off-by: Jamal Hadi Salim <[EMAIL PROTECTED]>

---
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index ebd7313..ce64eb2 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -27,6 +27,19 @@ config NETDEVICES
 # that for each of the symbols.
 if NETDEVICES
 
+config IFB
+       tristate "Intermediate Functional Block support"
+       depends on NET_CLS_ACT
+       ---help---
+         This is an intermidiate driver that allows sharing of
+         resources.
+         To compile this driver as a module, choose M here: the module
+         will be called inter.  If you want to use more than one inter
+         device at a time, you need to compile this driver as a module.
+         Instead of 'ifb', the devices will then be called 'ifb0',
+         'ifb1' etc.
+         Look at the iproute2 documentation directory for usage etc
+
 config DUMMY
        tristate "Dummy net driver support"
        ---help---
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index 4cffd34..66878a1 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -121,6 +121,7 @@ ifeq ($(CONFIG_SLIP_COMPRESSED),y)
 endif
 
 obj-$(CONFIG_DUMMY) += dummy.o
+obj-$(CONFIG_IFB) += ifb.o
 obj-$(CONFIG_DE600) += de600.o
 obj-$(CONFIG_DE620) += de620.o
 obj-$(CONFIG_LANCE) += lance.o
diff --git a/drivers/net/ifb.c b/drivers/net/ifb.c
new file mode 100644
index 0000000..d409118
--- /dev/null
+++ b/drivers/net/ifb.c
@@ -0,0 +1,292 @@
+/* drivers/net/ifb.c: 
+
+       The purpose of this driver is to provide a device that allows
+       for sharing of resources:
+
+       1) qdiscs/policies that are per device as opposed to system wide.
+       This now allows for sharing.
+
+       2) Allows for queueing incoming traffic for shaping instead of
+       dropping. 
+       
+       The original concept is based on what is known as the IMQ
+       driver <TBA: who wrote or maintains IMQ>
+
+       You need the tc action  mirror or redirect to feed this device
+               packets.
+
+       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.
+ 
+       Authors:        Jamal Hadi Salim (2005)
+ 
+*/
+
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <net/pkt_sched.h> 
+
+#define TX_TIMEOUT  (2*HZ)
+                                                                               
 
+#define TX_Q_LIMIT    32
+struct ifb_private {
+       struct net_device_stats stats;
+       struct tasklet_struct   ifb_tasklet;
+       int     tasklet_pending;
+       /* mostly debug stats leave in for now */
+       unsigned long   st_task_enter; /* tasklet entered */
+       unsigned long   st_txq_refl_try; /* transmit queue refill attempt */
+       unsigned long   st_rxq_enter; /* receive queue entered */
+       unsigned long   st_rx2tx_tran; /* receive to trasmit transfers */
+       unsigned long   st_rxq_notenter; /*receiveQ not entered, resched */
+       unsigned long   st_rx_frm_egr; /* received from egress path */
+       unsigned long   st_rx_frm_ing; /* received from ingress path */
+       unsigned long   st_rxq_check;
+       unsigned long   st_rxq_rsch;
+       struct sk_buff_head     rq;
+       struct sk_buff_head     tq;
+};
+
+static int numifbs = 1;
+
+static void ri_tasklet(unsigned long dev);
+static int ifb_xmit(struct sk_buff *skb, struct net_device *dev);
+static struct net_device_stats *ifb_get_stats(struct net_device *dev);
+static int ifb_open(struct net_device *dev);
+static int ifb_close(struct net_device *dev);
+
+static void ri_tasklet(unsigned long dev) 
+{
+
+       struct net_device *_dev = (struct net_device *)dev;
+       struct ifb_private *dp = netdev_priv(_dev);
+       struct net_device_stats *stats = &dp->stats;
+       struct sk_buff *skb;
+
+       dp->st_task_enter++;
+       if ((skb = skb_peek(&dp->tq)) == NULL) {
+               dp->st_txq_refl_try++;
+               if (spin_trylock(&_dev->xmit_lock)) {
+                       dp->st_rxq_enter++;
+                       while ((skb = skb_dequeue(&dp->rq)) != NULL) {
+                               skb_queue_tail(&dp->tq, skb);
+                               dp->st_rx2tx_tran++;
+                       }
+                       spin_unlock(&_dev->xmit_lock);
+               } else {
+                       /* reschedule */
+                       dp->st_rxq_notenter++;
+                       goto resched;
+               }
+       }
+
+       while ((skb = skb_dequeue(&dp->tq)) != NULL) {
+               u32 from = G_TC_FROM(skb->tc_verd);
+
+               skb->tc_verd = 0;
+               skb->tc_verd = SET_TC_NCLS(skb->tc_verd);
+               stats->tx_packets++;
+               stats->tx_bytes +=skb->len;
+               if (from & AT_EGRESS) {
+                       dp->st_rx_frm_egr++;
+                       dev_queue_xmit(skb);
+               } else if (from & AT_INGRESS) {
+
+                       dp->st_rx_frm_ing++;
+                       netif_rx(skb);
+               } else {
+                       dev_kfree_skb(skb);
+                       stats->tx_dropped++;
+               }
+       }
+
+       if (spin_trylock(&_dev->xmit_lock)) {
+               dp->st_rxq_check++;
+               if ((skb = skb_peek(&dp->rq)) == NULL) {
+                       dp->tasklet_pending = 0;
+                       if (netif_queue_stopped(_dev))
+                               netif_wake_queue(_dev);
+               } else {
+                       dp->st_rxq_rsch++;
+                       spin_unlock(&_dev->xmit_lock);
+                       goto resched;
+               }
+               spin_unlock(&_dev->xmit_lock);
+       } else {
+resched:
+               dp->tasklet_pending = 1;
+               tasklet_schedule(&dp->ifb_tasklet);
+       }
+
+}
+
+static void __init ifb_setup(struct net_device *dev)
+{
+       /* Initialize the device structure. */
+       dev->get_stats = ifb_get_stats;
+       dev->hard_start_xmit = ifb_xmit;
+       dev->open = &ifb_open;
+       dev->stop = &ifb_close;
+
+       /* Fill in device structure with ethernet-generic values. */
+       ether_setup(dev);
+       dev->tx_queue_len = TX_Q_LIMIT;
+       dev->change_mtu = NULL;
+       dev->flags |= IFF_NOARP;
+       dev->flags &= ~IFF_MULTICAST;
+       SET_MODULE_OWNER(dev);
+       random_ether_addr(dev->dev_addr);
+}
+
+static int ifb_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+       struct ifb_private *dp = netdev_priv(dev);
+       struct net_device_stats *stats = &dp->stats;
+       int ret = 0;
+       u32 from = G_TC_FROM(skb->tc_verd);
+
+       stats->tx_packets++;
+       stats->tx_bytes+=skb->len;
+
+       if (!from || !skb->input_dev) {
+dropped:
+               dev_kfree_skb(skb);
+               stats->rx_dropped++;
+               return ret;
+       } else {
+               /* 
+                * note we could be going
+                * ingress -> egress or
+                * egress -> ingress
+               */
+               skb->dev = skb->input_dev;
+               skb->input_dev = dev;
+               if (from & AT_INGRESS) {
+                       skb_pull(skb, skb->dev->hard_header_len);
+               } else {
+                       if (!(from & AT_EGRESS)) {
+                               goto dropped;
+                       }
+               }
+       }
+
+       if (skb_queue_len(&dp->rq) >= dev->tx_queue_len) {
+               netif_stop_queue(dev);
+       }
+
+       dev->trans_start = jiffies;
+       skb_queue_tail(&dp->rq, skb);
+       if (!dp->tasklet_pending) {
+               dp->tasklet_pending = 1;
+               tasklet_schedule(&dp->ifb_tasklet);
+       }
+
+       return ret;
+}
+
+static struct net_device_stats *ifb_get_stats(struct net_device *dev)
+{
+       struct ifb_private *dp = netdev_priv(dev);
+       struct net_device_stats *stats = &dp->stats;
+
+       pr_debug("tasklets stats %ld:%ld:%ld:%ld:%ld:%ld:%ld:%ld:%ld \n",
+               dp->st_task_enter, dp->st_txq_refl_try, dp->st_rxq_enter, 
+               dp->st_rx2tx_tran dp->st_rxq_notenter, dp->st_rx_frm_egr,
+               dp->st_rx_frm_ing, dp->st_rxq_check, dp->st_rxq_rsch );
+
+       return stats;
+}
+
+static struct net_device **ifbs;
+
+/* Number of ifb devices to be set up by this module. */
+module_param(numifbs, int, 0);
+MODULE_PARM_DESC(numifbs, "Number of ifb devices");
+
+static int ifb_close(struct net_device *dev)
+{
+       struct ifb_private *dp = netdev_priv(dev);
+
+       tasklet_kill(&dp->ifb_tasklet);
+       skb_queue_purge(&dp->rq);
+       skb_queue_purge(&dp->tq);
+       netif_stop_queue(dev);
+       return 0;
+}
+
+static int ifb_open(struct net_device *dev)
+{
+       struct ifb_private *dp = netdev_priv(dev);
+
+       tasklet_init(&dp->ifb_tasklet, ri_tasklet, (unsigned long)dev);
+       skb_queue_head_init(&dp->rq);
+       skb_queue_head_init(&dp->tq);
+       netif_start_queue(dev);
+
+       return 0;
+}
+
+static int __init ifb_init_one(int index)
+{
+       struct net_device *dev_ifb;
+       int err;
+
+       dev_ifb = alloc_netdev(sizeof(struct ifb_private),
+                                "ifb%d", ifb_setup);
+
+       if (!dev_ifb)
+               return -ENOMEM;
+
+       if ((err = register_netdev(dev_ifb))) {
+               free_netdev(dev_ifb);
+               dev_ifb = NULL;
+       } else {
+               ifbs[index] = dev_ifb; 
+       }
+
+       return err;
+}
+
+static void ifb_free_one(int index)
+{
+       unregister_netdev(ifbs[index]);
+       free_netdev(ifbs[index]);
+} 
+
+static int __init ifb_init_module(void)
+{ 
+       int i, err = 0;
+       ifbs = kmalloc(numifbs * sizeof(void *), GFP_KERNEL); 
+       if (!ifbs)
+               return -ENOMEM; 
+       for (i = 0; i < numifbs && !err; i++)
+               err = ifb_init_one(i); 
+       if (err) { 
+               while (--i >= 0)
+                       ifb_free_one(i);
+       }
+
+       return err;
+} 
+
+static void __exit ifb_cleanup_module(void)
+{
+       int i;
+
+       for (i = 0; i < numifbs; i++) 
+               ifb_free_one(i); 
+       kfree(ifbs);    
+}
+
+module_init(ifb_init_module);
+module_exit(ifb_cleanup_module);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jamal Hadi Salim");

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