Messages in this thread | | | Subject | Re: [PATCH] TOMOYO: Add garbage collector support. (v2) | From | Tetsuo Handa <> | Date | Wed, 27 May 2009 10:25:28 +0900 |
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Hello.
Paul E. McKenney wrote: > The list_del_rcu() primitive is designed for removing elements from > lists that have concurrent readers, and it therefore avoids changing the > ->next pointer. That said, I don't immediately see whether or not there > is some other reason you need to keep it on the list. And do you need > the ->prev pointer to stay valid? If not, you might be able to use it > in place of the ->is_deleted flag.
I don't need ->prev pointer.
> > Use of RCU does not help here because we need to keep the item valid as long as > > the item is referred by ->read_var1 or ->read_var2 or ->write_var1 . > > You would indeed need some way of tracking those references. One > approach is to make the RCU callback check to see if any of them > reference the to-be-deleted object, reposting itself if so. This > approach assumes that such a reference is short-lived, of course. > > If the ->read_var1 and other references are long-lived, could you > post an RCU callback when the last such reference was removed?
The reference stored in ->read_var1 / ->read_var2 / ->write_var1 are long-lived (it varies from less than one second to more than many hours).
Well, it's time for me to read all Documentation/RCU/* .
Thanks.
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