[EXTERNAL] Re: [PATCH v2 3/6] powerpc/eeh: Improve debug messages around device addition

[Sam Bobroff]

On Thu, Jun 20, 2019 at 01:45:24PM +1000, Oliver O'Halloran wrote:
> On Thu, Jun 20, 2019 at 12:40 PM Alexey Kardashevskiy <aik at ozlabs.ru> wrote:
> >
> > On 19/06/2019 14:27, Sam Bobroff wrote:
> > > On Tue, Jun 11, 2019 at 03:47:58PM +1000, Alexey Kardashevskiy wrote:
> > >>
> > >> On 07/05/2019 14:30, Sam Bobroff wrote:
> > >>> Also remove useless comment.
> > >>>
> > >>> Signed-off-by: Sam Bobroff <sbobroff at linux.ibm.com>
> > >>> Reviewed-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> > >>> ---
> > *snip*
> > >
> > > I can see that edev will be non-NULL here, but that pr_debug() pattern
> > > (using the PDN information to form the PCI address) is quite common
> > > across the EEH code, so I think rather than changing a couple of
> > > specific cases, I should do a separate cleanup patch and introduce
> > > something like pdn_debug(pdn, "...."). What do you think?
> >
> > I'd switch them all to already existing dev_dbg/pci_debug rather than
> > adding pdn_debug as imho it should not have been used in the first place
> > really...
> >
> > > (I don't know exactly when edev->pdev can be NULL.)
> >
> > ... and if you switch to dev_dbg/pci_debug, I think quite soon you'll
> > know if it can or cannot be NULL :)
> 
> As far as I can tell edev->pdev is NULL in two cases:
> 
> 1. Before eeh_device_add_late() has been called on the pdev. The late
> part of the add maps the pdev to an edev and sets the pdev's edev
> pointer and vis a vis.
> 2. While recoverying EEH unaware devices. Unaware devices are
> destroyed and rescanned and the edev->pdev pointer is cleared by
> pcibios_device_release()
> 
> In most of these cases it should be safe to use the pci_*() functions
> rather than making a new one up for printing pdns. In the cases where
> we might not have a PCI dev i'd make a new set of prints that take an
> EEH dev rather than a pci_dn since i'd like pci_dn to die sooner
> rather than later.
> 
> Oliver

I'll change the calls in {pnv,pseries}_pcibios_bus_add_device() and
eeh_add_device_late() to use dev_dbg() and post a new version.

For {pnv,pseries}_eeh_probe() I'm not sure what we can do; there's no
pci_dev available yet and while it would be nice to use the eeh_dev
rather than the pdn, it doesn't seem to have the bus/device/fn
information we need. Am I missing something there?  (The code in the
probe functions seems to get it from the pci_dn.)

If there isn't an easy way around this, would it therefore be reasonable
to just leave them open-coded as they are?

Cheers,
Sam.
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