Re: [Xen-devel] [PATCH] linux_gntshr_munmap: munmap takes a length, not a page count

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 03/09/14 15:17, Ian Campbell wrote:
> On Wed, 2014-09-03 at 15:15 +0100, David Vrabel wrote:
>> On 03/09/14 15:01, Ian Campbell wrote:
>>> On Mon, 2014-09-01 at 13:16 +0100, David Scott wrote:
>>>> This fixes a bug where if a client shares more than 1 page, the
>>>> munmap call fails to clean up everything. A process which does
>>>> a lot of sharing and unsharing can run out of resources.
>>>
>>> The doc comment on xc_gntshr_munmap does say count is in pages, so your
>>> change is correct but all of the in tree callers seem to pass a number
>>> of bytes not a number of pages. i.e. everything in tools/libvchan passes
>>> n*PAGE_SIZE.
>>>
>>> So I don't think this change is complete without also updating those.
>>
>> Would the corrent non-ABI/API-breaking fix be to just update the
>> documentation?
> 
> libxc doesn't have a stable API or ABI.

xc_gntshr_*() really should be part of a separate libxc-for-domu that
does have a stable ABI.  But since it isn't yet...

> My thinking in this case was that @count being pages was consistent with
> other related functions in the API and also avoids issues of what to do
> if count%4096 != 0.

...this sounds reasonable.

David

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