Re: [RFC][PATCH] ps command race fix take2 [1/4] list token

From: KAMEZAWA Hiroyuki
Date: Tue Aug 22 2006 - 07:18:07 EST

On 22 Aug 2006 13:06:34 +0200
Andi Kleen <ak@xxxxxxx> wrote:

> KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> writes:
> >
> > listtoken , a helper for walking a list by intermittent access.
> >
> > When we walk a list intermittently and the list is being modified at the
> > same time, it's hard to remember our position in it.
> >
> > With this list token, a user can remember where he is reading by inserting
> > a token in the list.
> I think the header/code needs much more comments so that other people
> can still make sense of it later. Even with the commit log it's not
> quite clear how it works.
Okay, make them more informative.

> Also locking needs to be explained.
Yes, with RCU. we need appropriate lock.

> I suppose only one user is allowed to use a token at one time?
Yes, I expext that a user uses a token. But several tokens can be inserted to a list.

> But overall it's a good idea to have a generic facility like this.
> I suppose it will be a more common problem in the future.


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