Re: [PATCH v1 1/6] mm: Section numbers use the type "unsigned long"

David Hildenbrand
2019-06-14T19:35:08Z

On 14.06.19 21:00, Andrew Morton wrote:
> On Fri, 14 Jun 2019 12:01:09 +0200 David Hildenbrand <david@redhat.com> wrote:
>
>> We are using a mixture of "int" and "unsigned long". Let's make this
>> consistent by using "unsigned long" everywhere. We'll do the same with
>> memory block ids next.
>>
>> ...
>>
>> - int i, ret, section_count = 0;
>> + unsigned long i;
>>
>> ...
>>
>> - unsigned int i;
>> + unsigned long i;
>
> Maybe I did too much fortran back in the day, but I think the
> expectation is that a variable called "i" has type "int".
>
> This?

t460s: ~/git/linux memory_block_devices2 $ git grep "unsigned long i;" |
wc -l
245
t460s: ~/git/linux memory_block_devices2 $ git grep "int i;" | wc -l
26827

Yes ;)

While it makes sense for the second and third occurrence, I think for
the first one it could be confusing (it's not actually a section number
but a counter for sections_per_block).

I see just now that we can avoid converting the first occurrence
completely. So maybe we should drop changing removable_show() from this
patch.

Cheers!

>
>
>
> s/unsigned long i/unsigned long section_nr/
>
> --- a/drivers/base/memory.c~mm-section-numbers-use-the-type-unsigned-long-fix
> +++ a/drivers/base/memory.c
> @@ -131,17 +131,17 @@ static ssize_t phys_index_show(struct de
> static ssize_t removable_show(struct device *dev, struct device_attribute *attr,
> char *buf)
> {
> - unsigned long i, pfn;
> + unsigned long section_nr, pfn;
> int ret = 1;
> struct memory_block *mem = to_memory_block(dev);
>
> if (mem->state != MEM_ONLINE)
> goto out;
>
> - for (i = 0; i < sections_per_block; i++) {
> - if (!present_section_nr(mem->start_section_nr + i))
> + for (section_nr = 0; section_nr < sections_per_block; section_nr++) {
> + if (!present_section_nr(mem->start_section_nr + section_nr))
> continue;
> - pfn = section_nr_to_pfn(mem->start_section_nr + i);
> + pfn = section_nr_to_pfn(mem->start_section_nr + section_nr);
> ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
> }
>
> @@ -695,12 +695,12 @@ static int add_memory_block(unsigned lon
> {
> int ret, section_count = 0;
> struct memory_block *mem;
> - unsigned long i;
> + unsigned long section_nr;
>
> - for (i = base_section_nr;
> - i < base_section_nr + sections_per_block;
> - i++)
> - if (present_section_nr(i))
> + for (section_nr = base_section_nr;
> + section_nr < base_section_nr + sections_per_block;
> + section_nr++)
> + if (present_section_nr(section_nr))
> section_count++;
>
> if (section_count == 0)
> @@ -823,7 +823,7 @@ static const struct attribute_group *mem
> */
> int __init memory_dev_init(void)
> {
> - unsigned long i;
> + unsigned long section_nr;
> int ret;
> int err;
> unsigned long block_sz;
> @@ -840,9 +840,9 @@ int __init memory_dev_init(void)
> * during boot and have been initialized
> */
> mutex_lock(&mem_sysfs_mutex);
> - for (i = 0; i <= __highest_present_section_nr;
> - i += sections_per_block) {
> - err = add_memory_block(i);
> + for (section_nr = 0; section_nr <= __highest_present_section_nr;
> + section_nr += sections_per_block) {
> + err = add_memory_block(section_nr);
> if (!ret)
> ret = err;
> }
> _
>

--

Thanks,

David / dhildenb