[PATCH 1/2] remove CONFIG_HAVE_ARCH_DEV_ALLOC_SKB

[PATCH 1/2] remove CONFIG_HAVE_ARCH_DEV_ALLOC_SKB

[Christoph Hellwig]

skbuff.h has an #ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB to allow
architectures to reimplement __dev_alloc_skb.  It's not set on any
architecture and now that we have an architecture-overrideable
NET_SKB_PAD there is not point at all to have one either.


Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: linux-2.6/include/linux/skbuff.h
===================================================================
--- linux-2.6.orig/include/linux/skbuff.h	2006-07-06 14:21:20.000000000 +0200
+++ linux-2.6/include/linux/skbuff.h	2006-07-06 15:11:00.000000000 +0200
@@ -1066,7 +1066,6 @@
 		kfree_skb(skb);
 }
 
-#ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB
 /**
  *	__dev_alloc_skb - allocate an skbuff for sending
  *	@length: length to allocate
@@ -1087,9 +1086,6 @@
 		skb_reserve(skb, NET_SKB_PAD);
 	return skb;
 }
-#else
-extern struct sk_buff *__dev_alloc_skb(unsigned int length, int gfp_mask);
-#endif
 
 /**
  *	dev_alloc_skb - allocate an skbuff for sending

Re: [PATCH 1/2] remove CONFIG_HAVE_ARCH_DEV_ALLOC_SKB

[David Miller]

From: Christoph Hellwig <hch@lst.de>
Date: Fri, 7 Jul 2006 11:10:08 +0200

> skbuff.h has an #ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB to allow
> architectures to reimplement __dev_alloc_skb.  It's not set on any
> architecture and now that we have an architecture-overrideable
> NET_SKB_PAD there is not point at all to have one either.
> 
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Applied, thanks Christoph.

Re: [PATCH 1/2] remove CONFIG_HAVE_ARCH_DEV_ALLOC_SKB

[Roland Dreier]

> skbuff.h has an #ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB to allow
> architectures to reimplement __dev_alloc_skb.  It's not set on any
> architecture and now that we have an architecture-overrideable
> NET_SKB_PAD there is not point at all to have one either.

I missed this when hch first posted it, sorry.

But my impression was that the intent of the config option was to let
Xen hook __dev_alloc_skb() to allocate special receive skbs to handle
their page-flipping virtual network device.  Which goes beyond
NET_SKB_PAD.

So the real question is about Xen hooks I guess -- and given where the
rest of Xen is, it probably does make sense to go ahead and strip this
out.

 - R.

Re: [PATCH 1/2] remove CONFIG_HAVE_ARCH_DEV_ALLOC_SKB

[Christoph Hellwig]

On Mon, Jul 24, 2006 at 03:44:15PM -0700, Roland Dreier wrote:
> > skbuff.h has an #ifndef CONFIG_HAVE_ARCH_DEV_ALLOC_SKB to allow
> > architectures to reimplement __dev_alloc_skb.  It's not set on any
> > architecture and now that we have an architecture-overrideable
> > NET_SKB_PAD there is not point at all to have one either.
> 
> I missed this when hch first posted it, sorry.
> 
> But my impression was that the intent of the config option was to let
> Xen hook __dev_alloc_skb() to allocate special receive skbs to handle
> their page-flipping virtual network device.  Which goes beyond
> NET_SKB_PAD.
> 
> So the real question is about Xen hooks I guess -- and given where the
> rest of Xen is, it probably does make sense to go ahead and strip this
> out.

If xen wants to use something else then dev_alloc_skb in their virtual
network driver that's totall fine.  No need to override the definiton of
dev_alloc_skb for that, though.  They can add their own xen_alloc_skb or
opencode the operation they want for it.

Note that overriding dev_alloc_skb is not just utterly pointless but would
even be harmfull in the case they'd finally add pci support for non-dom0
domains and used normaly NIC drivers in there.