Re: RFC: localcount_hadref() or localcount_trydarin()

[Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>]

Hi,

On 2017/06/12 21:51, Taylor R Campbell wrote:
>> Date: Mon, 12 Jun 2017 10:53:52 +0900
>> From: Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>
>>
>> I want to avoid detaching the encryption device while it is used by IPsec.
>> That is, once someone creates Security Assocatation(SA) to call
>> crypto_newsession(), the encryption device related the SA must not be
>> detached until the SA is flushed(done crypto_freesession()) and the SA
>> is not used(done crypto_dispatch() and cryptointr()).
> 
> Why don't you just use a global reference count first?  Is the latency
> and scalability of crypto_newsession and crypto_freesession critical?
> 
> I am not familiar with opencrypto -- maybe the answer is yes.  But in
> crypto_newsession, crypto_freesession, and cryptointr, you're still
> acquiring a global lock.  That defeats the purpose of using
> localcount, which is to make the latency and scalability of
> acquire/release no more than a CPU-local integer increment.

Exactly. At first, I tried to remove global lock in a single step using
localcount(9) and other tools, however I could not completely fix bugs.
So, I changed my policy. I restructure locks and define lock-orders at
first, and then I will remove global locks.
# This lock restructure also has the purpose to fix packet reordering.
# Yes, there are many tasks about opencrypto...

That is also the reason why I suspend implementation the patches shown
in my previous mail. Sorry to lack of talk again.

I will read your next mail, but I think it take time for me to read it
and consider the implementation. I reply this answer as soon as possible.


Thanks,

-- 
//////////////////////////////////////////////////////////////////////
Internet Initiative Japan Inc.

Device Engineering Section,
IoT Platform Development Department,
Network Division,
Technology Unit

Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>