kernel/linux.git/drivers/pci/hotplug/sgi_hotplug.c, branch v4.19.77

PCI: hotplug: Demidlayer registration with the core

2018-07-23T22:04:13+00:00

When a hotplug driver calls pci_hp_register(), all steps necessary for registration are carried out in one go, including creation of a kobject and addition to sysfs. That's a problem for pciehp once it's converted to enable/disable the slot exclusively from the IRQ thread: The thread needs to be spawned after creation of the kobject (because it uses the kobject's name), but before addition to sysfs (because it will handle enable/disable requests submitted via sysfs). pci_hp_deregister() does offer a ->release callback that's invoked after deletion from sysfs and before destruction of the kobject. But because pci_hp_register() doesn't offer a counterpart, hotplug drivers' ->probe and ->remove code becomes asymmetric, which is error prone as recently discovered use-after-free bugs in pciehp's ->remove hook have shown. In a sense, this appears to be a case of the midlayer antipattern: "The core thesis of the "midlayer mistake" is that midlayers are bad and should not exist. That common functionality which it is so tempting to put in a midlayer should instead be provided as library routines which can [be] used, augmented, or ignored by each bottom level driver independently. Thus every subsystem that supports multiple implementations (or drivers) should provide a very thin top layer which calls directly into the bottom layer drivers, and a rich library of support code that eases the implementation of those drivers. This library is available to, but not forced upon, those drivers." -- Neil Brown (2009), https://lwn.net/Articles/336262/ The presence of midlayer traits in the PCI hotplug core might be ascribed to its age: When it was introduced in February 2002, the blessings of a library approach might not have been well known: https://git.kernel.org/tglx/history/c/a8a2069f432c For comparison, the driver core does offer split functions for creating a kobject (device_initialize()) and addition to sysfs (device_add()) as an alternative to carrying out everything at once (device_register()). This was introduced in October 2002: https://git.kernel.org/tglx/history/c/8b290eb19962 The odd ->release callback in the PCI hotplug core was added in 2003: https://git.kernel.org/tglx/history/c/69f8d663b595 Clearly, a library approach would not force every hotplug driver to implement a ->release callback, but rather allow the driver to remove the sysfs files, release its data structures and finally destroy the kobject. Alternatively, a driver may choose to remove everything with pci_hp_deregister(), then release its data structures. To this end, offer drivers pci_hp_initialize() and pci_hp_add() as a split-up version of pci_hp_register(). Likewise, offer pci_hp_del() and pci_hp_destroy() as a split-up version of pci_hp_deregister(). Eliminate the ->release callback and move its code into each driver's teardown routine. Declare pci_hp_deregister() void, in keeping with the usual kernel pattern that enablement can fail, but disablement cannot. It only returned an error if the caller passed in a NULL pointer or a slot which has never or is no longer registered or is sharing its name with another slot. Those would be bugs, so WARN about them. Few hotplug drivers actually checked the return value and those that did only printed a useless error message to dmesg. Remove that. For most drivers the conversion was straightforward since it doesn't matter whether the code in the ->release callback is executed before or after destruction of the kobject. But in the case of ibmphp, it was unclear to me whether setting slot_cur->ctrl and slot_cur->bus_on to NULL needs to happen before the kobject is destroyed, so I erred on the side of caution and ensured that the order stays the same. Another nontrivial case is pnv_php, I've found the list and kref logic difficult to understand, however my impression was that it is safe to delete the list element and drop the references until after the kobject is destroyed. Signed-off-by: Lukas Wunner Signed-off-by: Bjorn Helgaas Acked-by: Andy Shevchenko # drivers/platform/x86 Cc: Rafael J. Wysocki Cc: Len Brown Cc: Scott Murray Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: Gavin Shan Cc: Sebastian Ott Cc: Gerald Schaefer Cc: Corentin Chary Cc: Darren Hart Cc: Andy Shevchenko

Merge branch 'pci/spdx' into next

2018-02-01T17:40:07+00:00

* pci/spdx: PCI: Add SPDX GPL-2.0+ to replace implicit GPL v2 or later statement PCI: Add SPDX GPL-2.0+ to replace GPL v2 or later boilerplate PCI: Add SPDX GPL-2.0 to replace COPYING boilerplate PCI: Add SPDX GPL-2.0 to replace GPL v2 boilerplate PCI: Add SPDX GPL-2.0 when no license was specified

PCI: Add SPDX GPL-2.0 to replace COPYING boilerplate

2018-01-28T21:48:54+00:00

Add SPDX GPL-2.0 to all PCI files that referred to the kernel default "COPYING" file, which specifies GPL version 2. Remove the boilerplate language referring to the GPL and "COPYING", relying on the assertion in b24413180f56 ("License cleanup: add SPDX GPL-2.0 license identifier to files with no license") that the SPDX identifier may be used instead of the full boilerplate text. Signed-off-by: Bjorn Helgaas Reviewed-by: Greg Kroah-Hartman

PCI: Add wrappers for dev_printk()

2018-01-18T18:55:24+00:00

Add PCI-specific dev_printk() wrappers and use them to simplify the code slightly. No functional change intended. Signed-off-by: Frederick Lawler [bhelgaas: squash into one patch] Signed-off-by: Bjorn Helgaas

PCI: Fix all whitespace issues

2016-01-08T16:35:24+00:00

Fix all whitespace issues (missing or needed whitespace) in all files in drivers/pci. Code is compiled with allyesconfig before and after code changes and objects are recorded and checked with objdiff and they are not changed after this commit. Signed-off-by: Bogicevic Sasa Signed-off-by: Bjorn Helgaas

ACPI: Introduce acpi_unload_parent_table() usages in Linux kernel

2015-01-26T15:08:49+00:00

ACPICA has implemented acpi_unload_parent_table() which can exactly replace the acpi_get_id()/acpi_unload_table_id() implemented in Linux kernel. The acpi_unload_parent_table() has been unit tested in ACPICA simulation environment. This patch can also help to reduce the source code differences between Linux and ACPICA. Signed-off-by: Lv Zheng Acked-by: Bjorn Helgaas Tested-by: Octavian Purdila Signed-off-by: Rafael J. Wysocki

PCI: Merge multi-line quoted strings

2014-06-11T02:20:42+00:00

Merge quoted strings that are broken across lines into a single entity. The compiler merges them anyway, but checkpatch complains about it, and merging them makes it easier to grep for strings. No functional change. [bhelgaas: changelog, do the same for everything under drivers/pci] Signed-off-by: Ryan Desfosses Signed-off-by: Bjorn Helgaas

PCI: Whitespace cleanup

2014-06-11T02:20:19+00:00

Fix various whitespace errors. No functional change. [bhelgaas: fix other similar problems] Signed-off-by: Ryan Desfosses Signed-off-by: Bjorn Helgaas

PCI: hotplug: Use global PCI rescan-remove locking

2014-01-14T19:14:25+00:00

Multiple race conditions are possible between PCI hotplug and the generic PCI bus rescan and device removal that can be triggered via sysfs. To avoid those race conditions make PCI hotplug use global PCI rescan-remove locking. Signed-off-by: Rafael J. Wysocki Signed-off-by: Bjorn Helgaas

ACPI / driver core: Store an ACPI device pointer in struct acpi_dev_node

2013-11-14T22:14:43+00:00

Modify struct acpi_dev_node to contain a pointer to struct acpi_device associated with the given device object (that is, its ACPI companion device) instead of an ACPI handle corresponding to it. Introduce two new macros for manipulating that pointer in a CONFIG_ACPI-safe way, ACPI_COMPANION() and ACPI_COMPANION_SET(), and rework the ACPI_HANDLE() macro to take the above changes into account. Drop the ACPI_HANDLE_SET() macro entirely and rework its users to use ACPI_COMPANION_SET() instead. For some of them who used to pass the result of acpi_get_child() directly to ACPI_HANDLE_SET() introduce a helper routine acpi_preset_companion() doing an equivalent thing. The main motivation for doing this is that there are things represented by struct acpi_device objects that don't have valid ACPI handles (so called fixed ACPI hardware features, such as power and sleep buttons) and we would like to create platform device objects for them and "glue" them to their ACPI companions in the usual way (which currently is impossible due to the lack of valid ACPI handles). However, there are more reasons why it may be useful. First, struct acpi_device pointers allow of much better type checking than void pointers which are ACPI handles, so it should be more difficult to write buggy code using modified struct acpi_dev_node and the new macros. Second, the change should help to reduce (over time) the number of places in which the result of ACPI_HANDLE() is passed to acpi_bus_get_device() in order to obtain a pointer to the struct acpi_device associated with the given "physical" device, because now that pointer is returned by ACPI_COMPANION() directly. Finally, the change should make it easier to write generic code that will build both for CONFIG_ACPI set and unset without adding explicit compiler directives to it. Signed-off-by: Rafael J. Wysocki Acked-by: Greg Kroah-Hartman Tested-by: Mika Westerberg # on Haswell Reviewed-by: Mika Westerberg Reviewed-by: Aaron Lu # for ATA and SDIO part