linux-kernel - Re: [QUESTION] llist: Comment releasing 'must delete' restriction before traversing

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Message-ID: <20180801085248.GA21343@X58A-UD3R>
Date:   Wed, 1 Aug 2018 17:52:48 +0900
From:   Byungchul Park <byungchul.park@....com>
To:     "Huang, Ying" <ying.huang@...el.com>
Cc:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org, kernel-team@....com,
        peterz@...radead.org, mingo@...nel.org, jiangshanlai@...il.com,
        josh@...htriplett.org, rostedt@...dmis.org,
        mathieu.desnoyers@...icios.com, joel@...lfernandes.org,
        len.brown@...el.com, glider@...gle.com, peter@...leysoftware.com,
        aik@...abs.ru
Subject: Re: [QUESTION] llist: Comment releasing 'must delete' restriction
 before traversing

On Wed, Aug 01, 2018 at 01:43:10PM +0800, Huang, Ying wrote:
> Byungchul Park <byungchul.park@....com> writes:
> 
> > I think rcu list also works well. But I decided to use llist because
> > llist is simpler and has one less pointer.
> >
> > Just to be sure, let me explain my use case more:
> >
> >    1. Introduced a global list where single linked list is sufficient.
> >    2. All operations I need is to add items and traverse the list.
> >    3. Ensure the operations always happen within irq-disabled section.
> >    4. I'm considering CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG properly.
> >    5. The list can be accessed by every CPU concurrently.
> >
> 
> Can you provide more information about where is your use case?  Is it a
> kernel driver?  Then it is better to submit the patch together with its
> user.
> 
> And I have the similar concern as Steven Rostedt.  That is, if you are
> the only user forever, it's not necessary to change the common code.

I'm sorry the patch is too complicated and premature to share at the
moment so I don't know how to extract only what you're asking me for.

Thanks anyway. The common code doesn't have to be changed then.

> Best Regards,
> Huang, Ying