Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH] radix_tree_tag_get() is not as safe as the docs make out | Date | Tue, 06 Apr 2010 22:18:58 +0100 |
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Nick Piggin <npiggin@suse.de> wrote:
> Nack, just drop the BUG_ON.
I can do that.
> I don't know what you mean by "untrustworthy answer".
I was thinking that the answer you get from radix_tree_tag_get() may be invalid if the tag chain is being modified as you read it. So if you do:
rcu_read_lock() ... x = radix_tree_tag_get(r, i, t); ... y = radix_tree_tag_get(r, i, t); ... rcu_read_unlock()
Then you can't guarantee that x == y, even though you were holding the RCU read lock.
As you suggested, I'll try and come up with a comment modification to this effect.
David
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