[PATCH 1/1] Punch a hole in /dev/mem for librtas

[Segher Boessenkool]

>>> +static inline int page_is_rtas_user_buf(unsigned long pfn)
>>> +{
>>> +	unsigned long paddr = (pfn << PAGE_SHIFT);
>>> +	if (paddr >= rtas_rmo_buf && paddr < (rtas_rmo_buf +
>>> RTAS_RMOBUF_MAX))
>>
>> It probably cannot overflow with actual values of rtas_rmo_buf
>> and RTAS_RMOBUF_MAX, but otherwise it is an incorrect test;
>> please write
>>
>> 	if (paddr >= rtas_rmo_buf && paddr - rtas_rmo_buf < RTAS_RMOBUF_MAX)
>>
>> (and, _MAX?  Shouldn't it be the actual size here?  Or is _MAX
>> just a confusing name :-) )
>
> The original code is a lot more readable and perfectly correct for all
> possible values of rtas_rmo_buf :-)

You have to consider those possible values before you see it cannot
overflow.  So no, it's a lot _less_ readable IMHO.

It's also a dangerous habit to get into.  Just say no :-)


Segher