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Subject: Re: [PATCH] CXL: Fix device_node reference counting
From: Michael Ellerman <mpe@ellerman.id.au>
To: Ian Munsie <imunsie@au1.ibm.com>
Date: Wed, 28 Jan 2015 17:07:45 +1100
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On Wed, 2015-01-28 at 16:53 +1100, Ian Munsie wrote:
> Excerpts from Michael Ellerman's message of 2015-01-28 16:04:40 +1100:
> > > I just wanted to check the status of this one? I can't see it in your
> > > tree and wanted to make sure you didn't simply miss it.
> > 
> > It looked fishy, but I never got around to replying.
> > 
> > The second sentence in the explanation should never be true:
> 
> Right, that was the point of the fix ;)

Sure, but bodging of_node_get()s all over the place is not a path to success.

> > You shouldn't have np unless you did an of_node_get() to get it, otherwise it's
> > pointing at something you don't have a reference for and it might go away at
> > any time.
> > 
> > So the patch may fix the bug but I don't think it's correct.
> > 
> > I think pnv_pci_to_phb_node() should be doing a get for you, before returning
> > the pointer.
> 
> Agreed - we should probably also rename it to have 'get' in the name,
> like pnv_pci_get_phb_node().

Yep.

> > See as a comparison pcibios_get_phb_of_node().
> 
> We could almost use that instead, except it's not exported for modules
> and I'm not sure if that even works with __weak functions?

It should. It's only weak until the final link and then you get a non-weak
version AIUI.

Try it.

And a follow up patch to have it use pci_bus_to_host() would be nice too.

cheers