>> >> > static inline unsigned int
>tbase_get_deferrable(tvec_base_t *base)
>> >> > {
>> >> > - return ((unsigned int)(unsigned long)base &
>> >TBASE_DEFERRABLE_FLAG);
>> >> > + return (unsigned int)((unsigned long)base &
>> >TBASE_DEFERRABLE_FLAG);
>> >> > }
>> >...
>> >> The change makes sense, but does it actually "fix" anything?
>> >>
>> >
>> >Yes - this first place fixes logical error, so it's a sin
>> >- even if not punishable in practice. (It's also unnecessary
>> >test for long to int conversion.)
>> >
>>
>> I am sorry, I don't understand. What is the logical error in
>the first
>> one?
>>
>> Actually, your change makes it different from what was originally
>> indended.
>> Original intention was to type convert base to a 32 bit value and
>> bitwise& with FLAG.
>
>But that is not what the original code is doing. If you wanted to
>typecast "base" to "a 32 bit value" then you should've used u32
>instead.
>
>Anyway, if you originally intended to actually typecast "base" to
>unsigned int, then you could do that directly without typecasting it
>first to unsigned long (unnecessarily) and then to unsigned int. Of
>course, if your system implements a pointer as something bigger than
>unsigned int (which is what you eventually convert "base" to), then
>you're screwed anyway and the intermediate typecast to unsigned long
>doesn't buy you anything at all.
On a 64 bit system, converting pointer to int causes unnecessary
compiler
warning, and intermediate long conversion was to avoid that. I will have
Whoa! Hello, hold on, just wait a second there. Do you _really_ want
an unsigned int return out of tbase_get_deferrable() or will an
unsigned long do? If the rest of your code is fine with unsigned long,
then I'd suggest something like:
static inline unsigned long tbase_get_deferrable(tvec_base_t *base)
{
return ((unsigned long)base & TBASE_DEFERRABLE_FLAG);
}
I don't really know your code (so I could be horribly incorrect here),
but personally I would prefer *heeding* to that warning than _hiding_
it -- it's not unnecessary, it's telling you that you're *losing* data
by converting a pointer (which is always unsigned long) to unsigned
int for 64-bit platforms where sizeof(void *) == sizeof(unsigned long)
== 8 bytes, but sizeof(unsigned int) == 4.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
