[PATCH] powerpc: add for_each_node_by_foo helpers

Benjamin Herrenschmidt benh at kernel.crashing.org
Mon Mar 13 10:29:52 EST 2006

On Sun, 2006-03-12 at 16:18 -0600, Nathan Lynch wrote:
> Benjamin Herrenschmidt wrote:
> > On Wed, 2006-03-08 at 16:47 +0100, Christoph Hellwig wrote:
> > > Typical use for of_find_node_by_name and of_find_node_by_type is to
> > > iterate over all nodes of a given type/name.  Add a helper macro to
> > > do that (in spirit of the list_for_each* macros).
> > 
> > Looks good. Maybe you have noted however that we aren't entirely safe
> > yet vs. device-tree being dynamic however. There is a per-node lock, but
> > no lock protecting the global node chain, which as usual means iterating
> > the list isn't entirely safe vs. removal...
> Eh?  There isn't any per-node lock, and the global chain is protected
> by a rwlock (devtree_lock).

I recently showed a variety of scenarios that would blow up in funny
ways.. It's not enough. It would only work if the global chain lock was
taken by callers before iterating.


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