Xen devel - Apr 2006 - [PATCH] linux: xenbus_be currently doesn''t build properly as a module

It depends on the non-exported symbols vmlist and vmlist_lock. As exporting
these doesn''t seem reasonable, the patch
disables the ability to build this as a module for now.

Signed-off-by: Jan Beulich <jbeulich@novell.com>



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On 20 Apr 2006, at 13:11, Jan Beulich wrote:
> It depends on the non-exported symbols vmlist and vmlist_lock. As 
> exporting these doesn''t seem reasonable, the patch
> disables the ability to build this as a module for now.
>
> Signed-off-by: Jan Beulich <jbeulich@novell.com>
A better fix is for xenbus_map_ring_valloc() to have the prototype:
struct vm_struct *xenbus_map_ring_valloc(struct xenbus_device *, int);

It then returns the vmarea that is allocated, or ERR_PTR() on error.

Then xenbus_unmap_ring_vfree() takes the vmarea rather than vaddr and 
we avoid the nasty vmlist scan that cannot be modularised.

There''s only one user of these functions right now, so the patch for 
this proper fix won''t be very big.

  -- Keir


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>>> Keir Fraser <Keir.Fraser@cl.cam.ac.uk> 20.04.06 15:08:28
>>>
>
>On 20 Apr 2006, at 13:11, Jan Beulich wrote:
>
>> It depends on the non-exported symbols vmlist and vmlist_lock. As 
>> exporting these doesn''t seem reasonable, the patch
>> disables the ability to build this as a module for now.
>>
>> Signed-off-by: Jan Beulich <jbeulich@novell.com>
>
>A better fix is for xenbus_map_ring_valloc() to have the prototype:
>struct vm_struct *xenbus_map_ring_valloc(struct xenbus_device *, int);
>
>It then returns the vmarea that is allocated, or ERR_PTR() on error.
>
>Then xenbus_unmap_ring_vfree() takes the vmarea rather than vaddr and 
>we avoid the nasty vmlist scan that cannot be modularised.
>
>There''s only one user of these functions right now, so the patch
for
>this proper fix won''t be very big.
I specifically didn''t do it this proper way because of the comment in
the function
saying doing it the raw way would be so much simpler - but if that in fact
doesn''t
apply...

Jan


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On 20 Apr 2006, at 14:33, Jan Beulich wrote:
>> There''s only one user of these functions right now, so the
patch for
>> this proper fix won''t be very big.
>
> I specifically didn''t do it this proper way because of the comment
in
> the function
> saying doing it the raw way would be so much simpler - but if that in 
> fact doesn''t
> apply...
The disadvantage of exposing the vmarea at the interface is outweighed 
by the advantage of being able to build as a module imo. Unless there 
is ever going to be a find_vm_area() call, this has to be considered 
the proper long-term fix to make it buildable as a module.

  -- Keir


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So here''s the adjusted patch. Jan
>>> Keir Fraser <Keir.Fraser@cl.cam.ac.uk> 20.04.06 15:08:28
>>>
On 20 Apr 2006, at 13:11, Jan Beulich wrote:
> It depends on the non-exported symbols vmlist and vmlist_lock. As 
> exporting these doesn''t seem reasonable, the patch
> disables the ability to build this as a module for now.
>
> Signed-off-by: Jan Beulich <jbeulich@novell.com>
A better fix is for xenbus_map_ring_valloc() to have the prototype:
struct vm_struct *xenbus_map_ring_valloc(struct xenbus_device *, int);

It then returns the vmarea that is allocated, or ERR_PTR() on error.

Then xenbus_unmap_ring_vfree() takes the vmarea rather than vaddr and 
we avoid the nasty vmlist scan that cannot be modularised.

There''s only one user of these functions right now, so the patch for 
this proper fix won''t be very big.

  -- Keir



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On 25 Apr 2006, at 14:00, Jan Beulich wrote:
> So here''s the adjusted patch. Jan
Looks good, I''ll check it in.

  Thanks,
  Keir


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