linux.git/arch/powerpc/kernel/pci-hotplug.c, branch v6.6

powerpc: Add missing headers

2022-05-08T12:15:40+00:00

Don't inherit headers "by chances" from asm/prom.h, asm/mpc52xx.h,
asm/pci.h etc...

Include the needed headers, and remove asm/prom.h when it was
needed exclusively for pulling necessary headers.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/be8bdc934d152a7d8ee8d1a840d5596e2f7d85e0.1646767214.git.christophe.leroy@csgroup.eu

powerpc/eeh: Release EEH device state synchronously

2020-05-18T11:58:44+00:00

EEH device state is currently removed (by eeh_remove_device()) during
the device release handler, which is invoked as the device's reference
count drops to zero. This may take some time, or forever, as other
threads may hold references.

However, the PCI device state is released synchronously by
pci_stop_and_remove_bus_device(). This mismatch causes problems, for
example the device may be re-discovered as a new device before the
release handler has been called, leaving the PCI and EEH state
mismatched.

So instead, call eeh_remove_device() from the bus device removal
handlers, which are called synchronously in the removal path.

Signed-off-by: Sam Bobroff 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/0a1f5105d3a33b1c090bba31de63eb0cdd25de7b.1588045502.git.sbobroff@linux.ibm.com

powerpc/eeh: Do early EEH init only when required

2020-03-25T01:09:38+00:00

The pci hotplug helper (pci_hp_add_devices()) calls
eeh_add_device_tree_early() to scan the device-tree for new PCI devices and
do the early EEH probe before the device is scanned. This early probe is a
no-op in a lot of cases because:

a) The early init is only required to satisfy a PAPR requirement that EEH
   be configured before we start doing config accesses. On PowerNV it is
   a no-op.

b) It's a no-op for devices that have already had their eeh_dev
   initialised.

There are four callers of pci_hp_add_devices():

1. arch/powerpc/kernel/eeh_driver.c
	Here the hotplug helper is called when re-scanning pci_devs that
	were removed during an EEH recovery pass. The EEH stat for each
	removed device (the eeh_dev) is retained across a recovery pass
	so the early init is a no-op in this case.

2. drivers/pci/hotplug/pnv_php.c
	This is also a no-op since the PowerNV hotplug driver is, suprisingly,
	PowerNV specific.

3. drivers/pci/hotplug/rpaphp_core.c
4. drivers/pci/hotplug/rpaphp_pci.c
	In these two cases new devices have been hotplugged and FW has
	provided new DT nodes for each. These are the only two cases where
	the EEH we might have new PCI device nodes in the DT so these are
	the only two cases where the early EEH probe needs to be done.

We can move the calls to eeh_add_device_tree_early() to the locations where
it's needed and remove it from the generic path. This is preparation for
making the early EEH probe pseries specific.

Reviewed-by: Sam Bobroff 
Signed-off-by: Oliver O'Halloran 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20200306073904.4737-3-oohall@gmail.com

powerpc/pci: Remove pcibios_setup_bus_devices()

2020-01-06T05:25:29+00:00

With the previous patch applied pcibios_setup_device() will always be run
when pcibios_bus_add_device() is called. There are several code paths where
pcibios_setup_bus_device() is still called (the PowerPC specific PCI
hotplug support is one) so with just the previous patch applied the setup
can be run multiple times on a device, once before the device is added
to the bus and once after.

There's no need to run the setup in the early case any more so just
remove it entirely.

Signed-off-by: Oliver O'Halloran 
Tested-by: Alexey Kardashevskiy 
Reviewed-by: Alexey Kardashevskiy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20191028085424.12006-3-oohall@gmail.com

powerpc/eeh: Fix race when freeing PDNs

2019-09-05T04:22:37+00:00

When hot-adding devices we rely on the hotplug driver to create pci_dn's
for the devices under the hotplug slot. Converse, when hot-removing the
driver will remove the pci_dn's that it created. This is a problem because
the pci_dev is still live until it's refcount drops to zero. This can
happen if the driver is slow to tear down it's internal state. Ideally, the
driver would not attempt to perform any config accesses to the device once
it's been marked as removed, but sometimes it happens. As a result, we
might attempt to access the pci_dn for a device that has been torn down and
the kernel may crash as a result.

To fix this, don't free the pci_dn unless the corresponding pci_dev has
been released.  If the pci_dev is still live, then we mark the pci_dn with
a flag that indicates the pci_dev's release function should free it.

Signed-off-by: Oliver O'Halloran 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20190903101605.2890-3-oohall@gmail.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

powerpc/pci: Unroll two pass loop when scanning bridges

2017-12-19T05:05:52+00:00

The current scanning code is really hard to understand because it calls the
same function in a loop where pass value is changed without any comments
explaining it:

  for (pass = 0; pass < 2; pass++)
    for_each_pci_bridge(dev, bus)
      max = pci_scan_bridge(bus, dev, max, pass);

Unfamiliar reader cannot tell easily what is the purpose of this loop
without looking at internals of pci_scan_bridge().

In order to make this bit easier to understand, open-code the loop in
pci_scan_child_bus() and pci_hp_add_bridge() with added comments.

No functional changes intended.

Signed-off-by: Andy Shevchenko 
Signed-off-by: Bjorn Helgaas 
Reviewed-by: Mika Westerberg

powerpc/pci: Use for_each_pci_bridge() helper

2017-12-19T05:05:52+00:00

Use for_each_pci_bridge() helper to make the code slightly cleaner.  No
functional change intended.

Requires: 24a0c654d7d6 ("PCI: Add for_each_pci_bridge() helper")
Signed-off-by: Andy Shevchenko 
Signed-off-by: Bjorn Helgaas 
Acked-by: Michael Ellerman

powerpc/pci: Don't scan empty slot

2016-05-11T11:54:26+00:00

In hotplug case, function pci_add_pci_devices() is called to rescan
the specified PCI bus, which might not have any child devices. Access
to the PCI bus's child device node will cause kernel crash without
exception.

This adds one more check to skip scanning PCI bus that doesn't have
any subordinate devices from device-tree, in order to avoid kernel
crash.

Signed-off-by: Gavin Shan 
Reviewed-by: Alexey Kardashevskiy 
Signed-off-by: Michael Ellerman

powerpc/pci: Move pci_find_bus_by_node() around

2016-05-11T11:54:24+00:00

This moves pci_find_bus_by_node() from arch/powerpc/platforms/
pseries/pci_dlpar.c to arch/powerpc/kernel/pci-hotplug.c so that
the function can be used by pSeries and PowerNV platform at the
same time. Also, below cleanup applied. No functional changes
introduced.

   * Remove variable "busdn" in find_bus_among_children()
   * Use PCI_DN() to convert device node to pci_dn

Signed-off-by: Gavin Shan 
Acked-by: Benjamin Herrenschmidt 
Reviewed-by: Andrew Donnellan 
Reviewed-by: Alexey Kardashevskiy 
Signed-off-by: Michael Ellerman