Re: [Xen-devel] [PATCH 2/2] x86/mm: Annotate gfn_get_* helpers as requiring non-NULL parameters

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.07.16 at 17:58, <george.dunlap@xxxxxxxxxx> wrote:
> On 27/07/16 19:08, Andrew Cooper wrote:
>> Introduce and use the nonnull attribute to help the compiler catch NULL
>> parameters being passed to function which require their parameters not to be
>> NULL.  Experimentally, GCC 4.9 on Debian Jessie only warns of non-NULL-ness
>> from immediate callers, so propagate the attributes out to all helpers.
>> 
>> A sample error looks like:
>> 
>> mem_sharing.c: In function ‘mem_sharing_nominate_page’:
>> mem_sharing.c:884:13: error: null argument where non-null required (argument 
> 3) [-Werror=nonnull]
>>              amfn = get_gfn_type_access(ap2m, gfn, NULL, &ap2ma, 0, NULL);
>>              ^
>> 
>> As part of this, replace the get_gfn_type_access() macro with an equivalent
>> static inline function for extra type safety, and the ability to be 
> annotated.
>> 
>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> 
> At a high level this looks like it's probably an improvement; I'd like
> to hear opinions of people who tend to have stronger opinions here first.

I agree on this being a desirable change.

Jan

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