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From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: "Mark Rutland" <mark.rutland@arm.com>,
	"Giovanni Cabiddu" <giovanni.cabiddu@intel.com>,
	"Rafał Miłecki" <zajec5@gmail.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	linux-pci@vger.kernel.org,
	"Alexander Duyck" <alexanderduyck@fb.com>,
	"Russell Currey" <ruscur@russell.cc>,
	"Sathya Prakash" <sathya.prakash@broadcom.com>,
	oss-drivers@corigine.com, "Paul Mackerras" <paulus@samba.org>,
	"H. Peter Anvin" <hpa@zytor.com>, "Jiri Olsa" <jolsa@redhat.com>,
	"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
	linux-perf-users@vger.kernel.org,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	"Herbert Xu" <herbert@gondor.apana.org.au>,
	linux-scsi@vger.kernel.org,
	"Michael Ellerman" <mpe@ellerman.id.au>,
	"Ido Schimmel" <idosch@nvidia.com>,
	x86@kernel.org, qat-linux@intel.com,
	"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Benjamin Herrenschmidt" <benh@kernel.crashing.org>,
	linux-wireless@vger.kernel.org,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Mathias Nyman" <mathias.nyman@intel.com>,
	"Yisen Zhuang" <yisen.zhuang@huawei.com>,
	"Fiona Trahe" <fiona.trahe@intel.com>,
	"Andrew Donnellan" <ajd@linux.ibm.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
	"Suganath Prabu Subramani"
	<suganath-prabu.subramani@broadcom.com>,
	"Simon Horman" <simon.horman@corigine.com>,
	"Arnaldo Carvalho de Melo" <acme@kernel.org>,
	"Borislav Petkov" <bp@alien8.de>, "Michael Buesch" <m@bues.ch>,
	"Jiri Pirko" <jiri@nvidia.com>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Namhyung Kim" <namhyung@kernel.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Andy Shevchenko" <andriy.shevchenko@intel.com>,
	"Juergen Gross" <jgross@suse.com>,
	"Salil Mehta" <salil.mehta@huawei.com>,
	"Sreekanth Reddy" <sreekanth.reddy@broadcom.com>,
	xen-devel@lists.xenproject.org,
	"Vadym Kochan" <vkochan@marvell.com>,
	MPT-FusionLinux.pdl@broadcom.com,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	linux-usb@vger.kernel.org,
	"Wojciech Ziemba" <wojciech.ziemba@intel.com>,
	linux-kernel@vger.kernel.org,
	"Taras Chornyi" <tchornyi@marvell.com>,
	"Zhou Wang" <wangzhou1@hisilicon.com>,
	linux-crypto@vger.kernel.org, kernel@pengutronix.de,
	netdev@vger.kernel.org, "Frederic Barrat" <fbarrat@linux.ibm.com>,
	"Oliver O'Halloran" <oohall@gmail.com>,
	linuxppc-dev@lists.ozlabs.org,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH v2 0/6] PCI: Drop duplicated tracking of a pci_dev's bound driver
Date: Fri, 6 Aug 2021 08:46:23 +0200	[thread overview]
Message-ID: <20210806064623.3lxl4clzbjpmchef@pengutronix.de> (raw)
In-Reply-To: <20210805234234.GA1797883@bjorn-Precision-5520>

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Hello Bjorn,

On Thu, Aug 05, 2021 at 06:42:34PM -0500, Bjorn Helgaas wrote:
> On Tue, Aug 03, 2021 at 12:01:44PM +0200, Uwe Kleine-König wrote:
> > Hello,
> > 
> > changes since v1 (https://lore.kernel.org/linux-pci/20210729203740.1377045-1-u.kleine-koenig@pengutronix.de):
> > 
> > - New patch to simplify drivers/pci/xen-pcifront.c, spotted and
> >   suggested by Boris Ostrovsky
> > - Fix a possible NULL pointer dereference I introduced in xen-pcifront.c
> > - A few whitespace improvements
> > - Add a commit log to patch #6 (formerly #5)
> > 
> > I also expanded the audience for patches #4 and #6 to allow affected
> > people to actually see the changes to their drivers.
> > 
> > Interdiff can be found below.
> > 
> > The idea is still the same: After a few cleanups (#1 - #3) a new macro
> > is introduced abstracting access to struct pci_dev->driver. All users
> > are then converted to use this and in the last patch the macro is
> > changed to make use of struct pci_dev::dev->driver to get rid of the
> > duplicated tracking.
> 
> I love the idea of this series!

\o/

> 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.

> Do you plan to do the same for all of them, or is there some reason
> why they need the pointer and PCI doesn't?

There is a list of cleanup stuff I intend to work on. Considering how
working on that list only made it longer in the recent past, maybe it
makes more sense to not work on it :-)

> In almost all cases, other buses define a "to_<bus>_driver()"
> interface.  In fact, PCI already has a to_pci_driver().
> 
> This series adds pci_driver_of_dev(), which basically just means we
> can do this:
> 
>   pdrv = pci_driver_of_dev(pdev);
> 
> instead of this:
> 
>   pdrv = to_pci_driver(pdev->dev.driver);
> 
> I don't see any other "<bus>_driver_of_dev()" interfaces, so I assume
> other buses just live with the latter style?  I'd rather not be
> different and have two ways to get the "struct pci_driver *" unless
> there's a good reason.

Among few the busses I already fixed in this regard pci was the first
that has a considerable amount of usage. So I considered it worth giving
it a name.
 
> 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?!

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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  reply	other threads:[~2021-08-06  6:49 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-03 10:01 Uwe Kleine-König
2021-08-03 10:01 ` [PATCH v2 4/6] PCI: Provide wrapper to access " Uwe Kleine-König
2021-08-03 14:37   ` Andy Shevchenko
2021-08-03 10:01 ` [PATCH v2 5/6] PCI: Adapt all code locations to not use struct pci_dev::driver directly Uwe Kleine-König
2021-08-03 13:53   ` Boris Ostrovsky
2021-08-03 14:38   ` Andy Shevchenko
2021-08-03 14:46   ` Ido Schimmel
2021-08-05 15:09   ` Andrew Donnellan
2021-08-03 10:01 ` [PATCH v2 6/6] PCI: Drop duplicated tracking of a pci_dev's bound driver Uwe Kleine-König
2021-08-05 23:42 ` [PATCH v2 0/6] " Bjorn Helgaas
2021-08-06  6:46   ` Uwe Kleine-König [this message]
2021-08-06 21:24     ` Bjorn Helgaas
2021-08-07  9:26       ` Uwe Kleine-König
2021-08-09 18:14         ` Bjorn Helgaas

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