On Tue, May 16, 2006 at 10:59:23AM +0400, Evgeniy Polyakov ([EMAIL PROTECTED]) 
wrote:
> On Mon, May 15, 2006 at 11:57:12PM -0700, David S. Miller ([EMAIL PROTECTED]) 
> wrote:
> > From: Evgeniy Polyakov <[EMAIL PROTECTED]>
> > Date: Tue, 16 May 2006 10:19:09 +0400
> > 
> > > +static int netchannel_convert_skb_ipv4(struct sk_buff *skb, struct 
> > > unetchannel *unc)
> > > +{
> >  ...
> > > + switch (unc->proto) {
> > > +         case IPPROTO_TCP:
> >  ...
> > > +         case IPPROTO_UDP:
> >  ...
> > 
> > Why do people write code like this?
> > 
> > Port location is protocol agnostic, there are always 2
> > 16-bit ports at beginning of header without exception.
> > 
> > Without this, ICMP would be useless :-)
> 
> And what if we use ESP which would place it's hashed sequence number as
> port?

Actually it should be one big hash, no matter if it is ipv4/tcp or
ipv6/esp, src/dst/sport/dport/proto were created just to allow easier
debug in ipv4 environment.

Attached patch for userspace copy:

--- /tmp/netchannel.1   2006-05-16 10:33:17.000000000 +0400
+++ /tmp/netchannel.2   2006-05-16 11:23:44.000000000 +0400
@@ -35,10 +35,10 @@
  
 diff --git a/include/linux/netchannel.h b/include/linux/netchannel.h
@@ -100,6 +100,7 @@
 +
 +      struct page *           (*nc_alloc_page)(unsigned int size);
 +      void                    (*nc_free_page)(struct page *page);
++      int                     (*nc_read_data)(struct netchannel *, unsigned 
int *len, void __user *arg);
 +
 +      struct sk_buff_head     list;
 +};
@@ -228,10 +229,10 @@
                ret = deliver_skb(skb, pt_prev, orig_dev);
 diff --git a/net/core/netchannel.c b/net/core/netchannel.c
 --- /dev/null
 +++ b/net/core/netchannel.c
-@@ -0,0 +1,583 @@
+@@ -0,0 +1,649 @@
 +/*
 + *    netchannel.c
 + * 
@@ -578,6 +579,40 @@
 +      return err;
 +}
 +
++/*
++ * Actually it should be something like recvmsg().
++ */
++static int netchannel_copy_to_user(struct netchannel *nc, unsigned int *len, 
void __user *arg)
++{
++      unsigned int copied;
++      struct sk_buff *skb;
++      struct iovec to;
++      int err = -EINVAL;
++      
++      to.iov_base = arg;
++      to.iov_len = *len;
++
++      skb = skb_dequeue(&nc->list);
++      if (!skb)
++              return -EAGAIN;
++
++      copied = skb->len;
++      if (copied > *len)
++              copied = *len;
++      
++      if (skb->ip_summed==CHECKSUM_UNNECESSARY) {
++              err = skb_copy_datagram_iovec(skb, 0, &to, copied);
++      } else {
++              err = skb_copy_and_csum_datagram_iovec(skb,0, &to);
++      }
++
++      *len = (err == 0)?copied:0;
++
++      kfree_skb(skb);
++
++      return err;
++}
++
 +static int netchannel_create(struct unetchannel *unc)
 +{
 +      struct netchannel *nc;
@@ -612,6 +647,8 @@
 +      atomic_set(&nc->refcnt, 1);
 +      memcpy(&nc->unc, unc, sizeof(struct unetchannel));
 +
++      nc->nc_read_data = &netchannel_copy_to_user;
++
 +      hlist_add_head_rcu(&nc->node, &bucket->head);
 +
 +out_unlock:
@@ -658,6 +695,30 @@
 +      return 0;
 +}
 +
++static int netchannel_recv_data(struct unetchannel_control *ctl, void __user 
*data)
++{
++      int ret = -ENODEV;
++      struct netchannel_cache_head *bucket;
++      struct netchannel *nc;
++      
++      bucket = netchannel_bucket(&ctl->unc);
++
++      mutex_lock(&bucket->mutex);
++
++      nc = netchannel_check_full(&ctl->unc, bucket);
++      if (!nc)
++              nc = netchannel_check_dest(&ctl->unc, bucket);
++
++      if (!nc)
++              goto out_unlock;
++
++      ret = nc->nc_read_data(nc, &ctl->len, data);
++
++out_unlock:
++      mutex_unlock(&bucket->mutex);
++      return ret;
++}
++
 +asmlinkage int sys_netchannel_control(void __user *arg)
 +{
 +      struct unetchannel_control ctl;
@@ -677,10 +738,16 @@
 +              case NETCHANNEL_REMOVE:
 +                      ret = netchannel_remove(&ctl.unc);
 +                      break;
++              case NETCHANNEL_READ:
++                      ret = netchannel_recv_data(&ctl, arg + sizeof(struct 
unetchannel_control));
++                      break;
 +              default:
 +                      ret = -EINVAL;
 +                      break;
 +      }
++      
++      if (copy_to_user(arg, &ctl, sizeof(struct unetchannel_control)))
++              return -ERESTARTSYS;
 +
 +      return ret;
 +}


-- 
        Evgeniy Polyakov
-
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