Message-ID: <20240131090023.12331-1-pstanner@redhat.com>
Date: Wed, 31 Jan 2024 10:00:19 +0100
From: Philipp Stanner <pstanner@...hat.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>,
	Arnd Bergmann <arnd@...db.de>,
	Johannes Berg <johannes@...solutions.net>,
	Randy Dunlap <rdunlap@...radead.org>,
	NeilBrown <neilb@...e.de>,
	John Sanpe <sanpeqf@...il.com>,
	Kent Overstreet <kent.overstreet@...il.com>,
	Niklas Schnelle <schnelle@...ux.ibm.com>,
	Philipp Stanner <pstanner@...hat.com>,
	Dave Jiang <dave.jiang@...el.com>,
	Uladzislau Koshchanka <koshchanka@...il.com>,
	"Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
	David Gow <davidgow@...gle.com>,
	Kees Cook <keescook@...omium.org>,
	Rae Moar <rmoar@...gle.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	"wuqiang.matt" <wuqiang.matt@...edance.com>,
	Yury Norov <yury.norov@...il.com>,
	Jason Baron <jbaron@...mai.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Marco Elver <elver@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ben Dooks <ben.dooks@...ethink.co.uk>,
	dakr@...hat.com
Cc: linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org,
	linux-arch@...r.kernel.org,
	stable@...r.kernel.org
Subject: [PATCH v6 0/4] Regather scattered PCI-Code

@Stable-Kernel:
You receive this patch series because its first patch fixes a leak in PCI.

@Bjorn:
I decided that it's now actually possible to just embed the docu updates
to the respective patches, instead of a separate patch.
Also dropped the ioport_unmap() for now.

Changes in v6:
- Remove the addition of ioport_unmap() from patch #1, since this is not
  really a bug, as explained by the comment above pci_iounmap. (Bjorn)
- Drop the patch unifying the two versions of pci_iounmap(). (Bjorn)
- Make patch #4's style congruent with PCI style.
- Drop (in any case empty) ioport_unmap() again from pci_iounmap()
- Add forgotten updates to Documentation/ when moving files from lib/ to
  drivers/pci/

Changes in v5:
- Add forgotten update to MAINTAINERS file.

Changes in v4:
- Apply Arnd's Reviewed-by's
- Add ifdef CONFIG_HAS_IOPORT_MAP guard in drivers/pci/iomap.c (build
  error on openrisc)
- Fix typo in patch no.5

Changes in v3:
- Create a separate patch for the leaks in lib/iomap.c. Make it the
  series' first patch. (Arnd)
- Turns out the aforementioned bug wasn't just accidentally removing
  iounmap() with the ifdef, it was also missing ioport_unmap() to begin
  with. Add it.
- Move the ARCH_WANTS_GENERIC_IOMEM_IS_IOPORT-mechanism from
  asm-generic/io.h to asm-generic/ioport.h. (Arnd)
- Adjust the implementation of iomem_is_ioport() in asm-generic/io.h so
  that it matches exactly what pci_iounmap() previously did in
  lib/pci_iomap.c. (Arnd)
- Move the CONFIG_HAS_IOPORT guard in asm-generic/io.h so that
  iomem_is_ioport() will always be compiled and just returns false if
  there are no ports.
- Add TODOs to several places informing about the generic
  iomem_is_ioport() in lib/iomap.c not being generic.
- Add TODO about the followup work to make drivers/pci/iomap.c's
  pci_iounmap() actually generic.

Changes in v2:
- Replace patch 4, previously extending the comment about pci_iounmap()
  in lib/iomap.c, with a patch that moves pci_iounmap() from that file
  to drivers/pci/iomap.c, creating a unified version there. (Arnd)
- Implement iomem_is_ioport() as a new helper in asm-generic/io.h and
  lib/iomap.c. (Arnd)
- Move the build rule in drivers/pci/Makefile for iomap.o under the
  guard of #if PCI. This had to be done because when just checking for
  GENERIC_PCI_IOMAP being defined, the functions don't disappear, which
  was the case previously in lib/pci_iomap.c, where the entire file was
  made empty if PCI was not set by the guard #ifdef PCI. (Intel's Bots)
- Rephares all patches' commit messages a little bit.


Sooooooooo. I reworked v1.

Please review this carefully, the IO-Ranges are obviously a bit tricky,
as is the build-system / ifdef-ery.

Arnd has suggested that architectures defining a custom inb() need their
own iomem_is_ioport(), as well. I've grepped for inb() and found the
following list of archs that define their own:
  - alpha
  - arm
  - m68k <--
  - parisc
  - powerpc
  - sh
  - sparc
  - x86 <--

All of those have their own definitons of pci_iounmap(). Therefore, they
don't need our generic version in the first place and, thus, also need
no iomem_is_ioport().
The two exceptions are x86 and m68k. The former uses lib/iomap.c through
CONFIG_GENERIC_IOMAP, as Arnd pointed out in the previous discussion
(thus, CONFIG_GENERIC_IOMAP is not really generic in this regard).

So as I see it, only m68k WOULD need its own custom definition of
iomem_is_ioport(). But as I understand it it doesn't because it uses the
one from asm-generic/pci_iomap.h ??

I wasn't entirely sure how to deal with the address ranges for the
generic implementation in asm-generic/io.h. It's marked with a TODO.
Input appreciated.

I removed the guard around define pci_iounmap in asm-generic/io.h. An
alternative would be to have it be guarded by CONFIG_GENERIC_IOMAP and
CONFIG_GENERIC_PCI_IOMAP, both. Without such a guard, there is no
collision however, because generic pci_iounmap() from
drivers/pci/iomap.c will only get pulled in when
CONFIG_GENERIC_PCI_IOMAP is actually set.

I cross-built this for a variety of architectures, including the usual
suspects (s390, m68k). So far successfully. But let's see what Intel's
robots say :O

P.


Original cover letter:

Hi!

So it seems that since ca. 2007 the PCI code has been scattered a bit.
PCI's devres code, which is only ever used by users of the entire
PCI-subsystem anyways, resides in lib/devres.c and is guarded by an
ifdef PCI, just as the content of lib/pci_iomap.c is.

It, thus, seems reasonable to move all of that.

As I were at it, I moved as much of the devres-specific code from pci.c
to devres.c, too. The only exceptions are four functions that are
currently difficult to move. More information about that can be read
here [1].

I noticed these scattered files while working on (new) PCI-specific
devres functions. If we can get this here merged, I'll soon send another
patch series that addresses some API-inconsistencies and could move the
devres-part of the four remaining functions.

I don't want to do that in this series as this here is only about moving
code, whereas the next series would have to actually change API
behavior.

I successfully (cross-)built this for x86, x86_64, AARCH64 and ARM
(allyesconfig). I booted a kernel with it on x86_64, with a Fedora
desktop environment as payload. The OS came up fine

I hope this is OK. If we can get it in, we'd soon have a very
consistent PCI API again.

Regards,
P.

Philipp Stanner (4):
  lib/pci_iomap.c: fix cleanup bug in pci_iounmap()
  lib: move pci_iomap.c to drivers/pci/
  lib: move pci-specific devres code to drivers/pci/
  PCI: Move devres code from pci.c to devres.c

 Documentation/driver-api/device-io.rst |   2 +-
 Documentation/driver-api/pci/pci.rst   |   6 +
 MAINTAINERS                            |   1 -
 drivers/pci/Kconfig                    |   5 +
 drivers/pci/Makefile                   |   3 +-
 drivers/pci/devres.c                   | 450 +++++++++++++++++++++++++
 lib/pci_iomap.c => drivers/pci/iomap.c |   5 +-
 drivers/pci/pci.c                      | 249 --------------
 drivers/pci/pci.h                      |  24 ++
 lib/Kconfig                            |   3 -
 lib/Makefile                           |   1 -
 lib/devres.c                           | 208 +-----------
 12 files changed, 490 insertions(+), 467 deletions(-)
 create mode 100644 drivers/pci/devres.c
 rename lib/pci_iomap.c => drivers/pci/iomap.c (99%)

-- 
2.43.0

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