Re: [PATCH liburing v2 0/8] aarch64 support

[Jens Axboe <axboe@kernel.dk>]

On 7/4/22 6:52 AM, Ammar Faizi wrote:
> On 6/30/22 12:58 AM, Ammar Faizi wrote:
>> From: Ammar Faizi <ammarfaizi2@gnuweeb.org>
>>
>> Hi Jens,
>>
>> This is v2 revision of aarch64 support.
>>
>> This series contains nolibc support for aarch64 and one extra irrelevant
>> cleanup (patch #1). The missing bit from aarch64 is get_page_size()
>> which is a bit complicated to implement without libc.
>>
>> aarch64 supports three values of page size: 4K, 16K, and 64K which are
>> selected at kernel compilation time. Therefore, we can't hard code the
>> page size for this arch. In this series we utilize open(), read() and
>> close() syscall to find the page size from /proc/self/auxv.
>>
>> The auxiliary vector contains information about the page size, it is
>> located at `AT_PAGESZ` keyval pair.
> 
> This no longer applies, I will send v3 revision soon. If you have some
> comments, let me know so I can address it together with the rebase.

Just send a v3, didn't have time to go fully over it yet. One note,
though - for patch 5, I'd split get_page_size() into two pieces so you
just do:

static inline long get_page_size(void)
{
	static long cache_val;

	if (cache_val)
		return cache_val;

	return __get_page_size();
}

With that, we can have __get_page_size() just do that one thing, open
the file and read the value.

No need to init static variables to 0.

And finally, if the read/open/whatever fails in __get_page_size(),
assign cache_val to the fallback value as well. I don't see a point in
retrying the same operation later and expect a different result.

-- 
Jens Axboe