Re: [Xen-devel] [PATCH v2 02/20] xen: Introduce a function to split a Linux page into Xen page

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 16/07/15 15:54, Julien Grall wrote:
> Hi Stefano,
>
> On 16/07/2015 16:23, Stefano Stabellini wrote:
>>> diff --git a/include/xen/page.h b/include/xen/page.h
>>> index 8ebd37b..b1f7722 100644
>>> --- a/include/xen/page.h
>>> +++ b/include/xen/page.h
>>> @@ -39,4 +39,24 @@ struct xen_memory_region
>>> xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS];
>>>
>>>   extern unsigned long xen_released_pages;
>>>
>>> +typedef int (*xen_pfn_fn_t)(struct page *page, unsigned long pfn,
>>> void *data);
>>> +/* Break down the page in 4KB granularity and call fn foreach xen
>>> pfn */
>>> +static inline int xen_apply_to_page(struct page *page, xen_pfn_fn_t
>>> fn,
>>> +                    void *data)
>>> +{
>>> +    unsigned long pfn = xen_page_to_pfn(page);
>>> +    int i;
>>> +    int ret;
>>
>> please initialize ret to 0
>
> Hmmm... right. I'm not sure why the compiler didn't catch it.

Because there is not a path where it can possibly be used
uninitialised.  The for() loop is guaranteed to execute at least once.

~Andrew

>
>>
>>> +    for (i = 0; i < XEN_PFN_PER_PAGE; i++, pfn++) {
>>> +        ret = fn(page, pfn, data);
>>> +        if (ret)
>>> +            return ret;
>>> +    }
>>> +
>>> +    return ret;
>>> +}
>>> +
>>> +
>>>   #endif    /* _XEN_PAGE_H */
>>
>>
>> Reviewed-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>
> Thank you,
>


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