Re: [Xen-devel] [PATCH v11 5/7] memory: add check_get_page_from_gfn() as a wrapper...

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Sep 19, 2018 at 09:36:00AM +0100, Paul Durrant wrote:
> ...for some uses of get_page_from_gfn().
> 
> There are many occurrences of the following pattern in the code:
> 
>     q = <readonly look-up> ? P2M_ALLOC : P2M_UNSHARE;
>     page = get_page_from_gfn(d, gfn, &p2mt, q);
> 
>     if ( p2m_is_paging(p2mt) )
>     {
>         if ( page )
>             put_page(page);
> 
>         p2m_mem_paging_populate(d, gfn);
>         return <-EAGAIN or equivalent>;
>     }
> 
>     if ( (q & P2M_UNSHARE) && p2m_is_shared(p2mt) )
>     {
>         if ( page )
>             put_page(page);
> 
>         return <-EAGAIN or equivalent>;
>     }
> 
>     if ( !page )
>         return <-EINVAL or equivalent>;
> 
> There are some small differences between the exact way the occurrences
> are coded but the desired semantic is the same.
> 
> This patch introduces a new common implementation of this code in
> check_get_page_from_gfn() and then converts the various open-coded patterns
> into calls to this new function.
> 
> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> Reviewed-by: Roger Pau Monne <roger.pau@xxxxxxxxxx>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>

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