linux-kernel - Re: [PATCH] powerpc/fsl_pci: Fix pci stack build bug with FRAME

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Date:	Thu, 22 Jan 2015 18:43:45 -0600
From:	Scott Wood <scottwood@...escale.com>
To:	Kim Phillips <kim.phillips@...escale.com>
CC:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Wang Dongsheng <dongsheng.wang@...escale.com>,
	Anton Blanchard <anton@...ba.org>,
	"Himangi Saraogi" <himangi774@...il.com>,
	Aaron Sierra <asierra@...-inc.com>,
	<linux-kernel@...r.kernel.org>, <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH] powerpc/fsl_pci: Fix pci stack build bug with FRAME_WARN

On Thu, 2015-01-22 at 18:20 -0600, Kim Phillips wrote:
> On Wed, 21 Jan 2015 21:02:27 -0600
> Scott Wood <scottwood@...escale.com> wrote:
> 
> > On Wed, 2015-01-21 at 20:48 -0600, Kim Phillips wrote:
> > > fake_pci_bus()' version is static, so it's not on the stack.
> > > 
> > > given that, maybe fsl_pcie_check_link()'s should be static too?
> > 
> > Oh.  How would you ensure that it's only called once at a time?  It
> > doesn't look like this is only called during early boot.
> > fsl_pcie_check_link() is called every time we do any config read through
> > the normal interface.  This is also a concern for the call to
> > early_read_config_dword().
> 
> I really don't know how that works: that code has been there since
> before linux was maintained in git.

Regardless, now that it's been noticed we should figure it out.
fsl_pcie_check_link() is using the early_*() functions in a context that
is not early and thus appears to be breaking the assumption that
fake_pci_bus() makes.

fsl_pcie_check_link() is fairly recent, FWIW.

> Below is the v2.

Please send as a standalone patch so I don't have to edit all the
discussion out of the commit message.

-Scott


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