Date:   Fri, 6 Aug 2021 16:24:52 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Cc:     Mark Rutland <mark.rutland@....com>,
        Giovanni Cabiddu <giovanni.cabiddu@...el.com>,
        Rafał Miłecki <zajec5@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-pci@...r.kernel.org, Alexander Duyck <alexanderduyck@...com>,
        Russell Currey <ruscur@...sell.cc>,
        Sathya Prakash <sathya.prakash@...adcom.com>,
        oss-drivers@...igine.com, Paul Mackerras <paulus@...ba.org>,
        "H. Peter Anvin" <hpa@...or.com>, Jiri Olsa <jolsa@...hat.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        linux-perf-users@...r.kernel.org,
        Stefano Stabellini <sstabellini@...nel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        linux-scsi@...r.kernel.org, Michael Ellerman <mpe@...erman.id.au>,
        Ido Schimmel <idosch@...dia.com>, x86@...nel.org,
        qat-linux@...el.com,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        linux-wireless@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Yisen Zhuang <yisen.zhuang@...wei.com>,
        Fiona Trahe <fiona.trahe@...el.com>,
        Andrew Donnellan <ajd@...ux.ibm.com>,
        Arnd Bergmann <arnd@...db.de>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Suganath Prabu Subramani 
        <suganath-prabu.subramani@...adcom.com>,
        Simon Horman <simon.horman@...igine.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Borislav Petkov <bp@...en8.de>, Michael Buesch <m@...s.ch>,
        Jiri Pirko <jiri@...dia.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Shevchenko <andriy.shevchenko@...el.com>,
        Juergen Gross <jgross@...e.com>,
        Salil Mehta <salil.mehta@...wei.com>,
        Sreekanth Reddy <sreekanth.reddy@...adcom.com>,
        xen-devel@...ts.xenproject.org, Vadym Kochan <vkochan@...vell.com>,
        MPT-FusionLinux.pdl@...adcom.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org,
        Wojciech Ziemba <wojciech.ziemba@...el.com>,
        linux-kernel@...r.kernel.org, Taras Chornyi <tchornyi@...vell.com>,
        Zhou Wang <wangzhou1@...ilicon.com>,
        linux-crypto@...r.kernel.org, kernel@...gutronix.de,
        netdev@...r.kernel.org, Frederic Barrat <fbarrat@...ux.ibm.com>,
        Oliver O'Halloran <oohall@...il.com>,
        linuxppc-dev@...ts.ozlabs.org,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v2 0/6] PCI: Drop duplicated tracking of a pci_dev's
 bound driver

On Fri, Aug 06, 2021 at 08:46:23AM +0200, Uwe Kleine-König wrote:
> On Thu, Aug 05, 2021 at 06:42:34PM -0500, Bjorn Helgaas wrote:

> > I looked at all the bus_type.probe() methods, it looks like pci_dev is
> > not the only offender here.  At least the following also have a driver
> > pointer in the device struct:
> > 
> >   parisc_device.driver
> >   acpi_device.driver
> >   dio_dev.driver
> >   hid_device.driver
> >   pci_dev.driver
> >   pnp_dev.driver
> >   rio_dev.driver
> >   zorro_dev.driver
> 
> Right, when I converted zorro_dev it was pointed out that the code was
> copied from pci and the latter has the same construct. :-)
> See
> https://lore.kernel.org/r/20210730191035.1455248-5-u.kleine-koenig@pengutronix.de
> for the patch, I don't find where pci was pointed out, maybe it was on
> irc only.

Oh, thanks!  I looked to see if you'd done something similar
elsewhere, but I missed this one.

> > Looking through the places that care about pci_dev.driver (the ones
> > updated by patch 5/6), many of them are ... a little dubious to begin
> > with.  A few need the "struct pci_error_handlers *err_handler"
> > pointer, so that's probably legitimate.  But many just need a name,
> > and should probably be using dev_driver_string() instead.
> 
> Yeah, I considered adding a function to get the driver name from a
> pci_dev and a function to get the error handlers. Maybe it's an idea to
> introduce these two and then use to_pci_driver(pdev->dev.driver) for the
> few remaining users? Maybe doing that on top of my current series makes
> sense to have a clean switch from pdev->driver to pdev->dev.driver?!

I'd propose using dev_driver_string() for these places:

  eeh_driver_name() (could change callers to use dev_driver_string())
  bcma_host_pci_probe()
  qm_alloc_uacce()
  hns3_get_drvinfo()
  prestera_pci_probe()
  mlxsw_pci_probe()
  nfp_get_drvinfo()
  ssb_pcihost_probe()

The use in mpt_device_driver_register() looks unnecessary: it's only
to get a struct pci_device_id *, which is passed to ->probe()
functions that don't need it.

The use in adf_enable_aer() looks wrong: it sets the err_handler
pointer in one of the adf_driver structs.  I think those structs
should be basically immutable, and the drivers that call
adf_enable_aer() from their .probe() methods should set
".err_handler = &adf_err_handler" in their static adf_driver
definitions instead.

I think that basically leaves these:

  uncore_pci_probe()     # .id_table, custom driver "registration"
  match_id()             # .id_table, arch/x86/kernel/probe_roms.c
  xhci_pci_quirks()      # .id_table
  pci_error_handlers()   # roll-your-own AER handling, drivers/misc/cxl/guest.c

I think it would be fine to use to_pci_driver(pdev->dev.driver) for
these few.

Bjorn

Powered by blists - more mailing lists