Re: [PATCH v4 1/7] interconnect: Add generic on-chip interconnect API

[Evan Green <evgreen@chromium.org>]

On Wed, Jun 6, 2018 at 11:09 AM Georgi Djakov <georgi.djakov@linaro.org> wrote:
>
> Hi Evan,
>
> On 06/06/2018 05:59 PM, Georgi Djakov wrote:
> >>> +
> >>> +/**
> >>> + * icc_node_create() - create a node
> >>> + * @id: node id
> >>> + *
> >>> + * Return: icc_node pointer on success, or ERR_PTR() on error
> >>> + */
> >>> +struct icc_node *icc_node_create(int id)
> >>> +{
> >>> +       struct icc_node *node;
> >>> +
> >>> +       /* check if node already exists */
> >>> +       node = node_find(id);
> >>> +       if (node)
> >>> +               return node;
> >>
> >> This is probably going to do more harm than good once icc_node_delete comes
> >> in, since it almost certainly indicates a programmer error or ID collision,
> >> and will likely result in a double free. We should probably fail with
> >> EEXIST instead.
> >
> > In the current approach we create the nodes one by one, and the linked
> > nodes are created when they are referenced. The other way around would
> > be to create first all the nodes and then populate the links to avoid
> > the "chicken and egg" problem.
> >
>
> Just to elaborate a bit more on that: We can't actually register all the
> nodes in advance, as we might have multiple interconnect providers
> probing in different order. Each provider may have nodes linking to
> nodes belonging to other providers (not probed yet). That's why we
> create the nodes on the first reference and then, when the actual
> provider driver is probed, the rest of the node data is filled.
>

Ah ok, the extra explanation helped a lot. This makes sense to me. Thanks.
-Evan