Re: [Xen-devel] [PATCH v8 3/8] xen/arm: return int *_dcache_va_range

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.10.14 at 16:57, <Ian.Campbell@xxxxxxxxxx> wrote:
>> --- a/xen/arch/arm/mm.c
>> +++ b/xen/arch/arm/mm.c
>> @@ -388,7 +388,7 @@ void flush_page_to_ram(unsigned long mfn)
>>  {
>>      void *v = map_domain_page(mfn);
>>  
>> -    clean_and_invalidate_dcache_va_range(v, PAGE_SIZE);
>> +    ASSERT(clean_and_invalidate_dcache_va_range(v, PAGE_SIZE) == 0);
> 
> Just this one assert? What about all the other callers of
> *_dcache_va_range?

I'm glad I looked at this reply (I skipped the original one because of
being ARM-only): Uses of ASSERT() like above won't work in non-
debug builds. You have to latch the result into a variable and assert
on it. The fundamental rule is: Expressions passed to ASSERT() must
never have side effects. That's different from BUG_ON(), but even
there Keir advocates not using expressions with side effects, aiui
both to avoid the above mistake (i.e. getting used to doing it the
right way) and to leave open the option of adding a build option to
eliminate the BUG()s and BUG_ON()s too.

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel