Re: [Xen-devel] bug in xc_gntshr_munmap?

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2013-04-26 at 12:07 +0100, Marek Marczykowski wrote:
> Hi,
> 
> Header says:
> /*
>  * Unmaps the @count pages starting at @start_address, which were mapped by a
>  * call to xc_gntshr_share_*. Never logs.
>  */
> int xc_gntshr_munmap(xc_gntshr *xcg, void *start_address, uint32_t count);
> 
> But implementation calls:
> static int linux_gntshr_munmap(xc_gntshr *xcg, xc_osdep_handle h,
>                                void *start_address, uint32_t count)
> {
>     return munmap(start_address, count);
> }
> 
> munmap(2) expect second argument to be size of mapped area (in bytes), not
> pages count.
> 
> Users of xc_gntshr_munmap (the only one I'm aware of is libxenvchan) already
> uses that broken semantic.
> 
> Is it going to be fixed (I can send trivial patch for both libxc and
> libxenvchan), or the comment in header should be updated?

I think the function should behave the same as the map side, whichever
that is.

Ian.


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