kernel/linux.git/include/linux/device/bus.h, branch v7.0-rc7

driver core: generalize driver_override in struct device

2026-03-17T19:30:23+00:00

Currently, there are 12 busses (including platform and PCI) that duplicate the driver_override logic for their individual devices. All of them seem to be prone to the bug described in [1]. While this could be solved for every bus individually using a separate lock, solving this in the driver-core generically results in less (and cleaner) changes overall. Thus, move driver_override to struct device, provide corresponding accessors for busses and handle locking with a separate lock internally. In particular, add device_set_driver_override(), device_has_driver_override(), device_match_driver_override() and generalize the sysfs store() and show() callbacks via a driver_override feature flag in struct bus_type. Until all busses have migrated, keep driver_set_override() in place. Note that we can't use the device lock for the reasons described in [2]. Link: https://bugzilla.kernel.org/show_bug.cgi?id=220789 [1] Link: https://lore.kernel.org/driver-core/DGRGTIRHA62X.3RY09D9SOK77P@kernel.org/ [2] Tested-by: Gui-Dong Han Co-developed-by: Gui-Dong Han Signed-off-by: Gui-Dong Han Reviewed-by: Greg Kroah-Hartman Link: https://patch.msgid.link/20260303115720.48783-2-dakr@kernel.org [ Use dev->bus instead of sp->bus for consistency; fix commit message to refer to the struct bus_type's driver_override feature flag. - Danilo ] Signed-off-by: Danilo Krummrich

Revert "driver core: enforce device_lock for driver_match_device()"

2026-03-03T12:12:42+00:00

This reverts commit dc23806a7c47 ("driver core: enforce device_lock for driver_match_device()") and commit 289b14592cef ("driver core: fix inverted "locked" suffix of driver_match_device()"). While technically correct, there is a major downside to this approach: When a device is already present in the system and a driver is registered on the same bus, we iterate over all devices registered on this bus to see if one of them matches. If we come across an already bound one where the corresponding driver crashed while holding the device lock (e.g. in probe()) we can't make any progress anymore. However, drivers are typically the least tested code in the kernel and hence it is a case that is likely to happen regularly. Besides hurting developer ergonomics, it potentially decreases chances of shutting things down cleanly and obtaining logs in production environments as well [1]. This came up in the context of a firewire bug, which only in combination with the reverted commit, caused the machine to hang [2]. Additionally, it was observed in [3]. Thus, revert commit dc23806a7c47 ("driver core: enforce device_lock for driver_match_device()") and add a brief note clarifying that an implementer of struct bus_type must not expect match() to be called with the device lock held. Link: https://lore.kernel.org/driver-core/DGRGTIRHA62X.3RY09D9SOK77P@kernel.org/ [1] Link: https://lore.kernel.org/all/67f655bb-4d81-4609-b008-68d200255dd2@davidgow.net/ [2] Link: https://lore.kernel.org/lkml/CALbr=LZ4v7N=tO1vgOsyj9AS+XuNbn6kG-QcF+PacdMjSo0iyw@mail.gmail.com/ [3] Reported-by: Linus Torvalds Closes: https://lore.kernel.org/driver-core/CAHk-=wgJ_L1C=HjcYJotg_zrZEmiLFJaoic+PWthjuQrutrfJw@mail.gmail.com/ Reviewed-by: Gui-Dong Han Acked-by: Greg Kroah-Hartman Link: https://patch.msgid.link/20260302002545.19389-1-dakr@kernel.org [ Add additional Link: reference. - Danilo ] Signed-off-by: Danilo Krummrich

driver core: make bus_find_device_by_acpi_dev() stub prototype aligned

2026-01-10T00:03:53+00:00

Currently the bus_find_device_by_acpi_dev() stub for !CONFIG_ACPI case takes a const void * parameter instead of const struct acpi_device *. As long as it's a pointer, we may named it as we want to with the help of a forward declaration. Hence move the declaration out of the ifdeffery and use the same prototype in both cases. This adds a bit of an additional type checking at a compilation time. Signed-off-by: Andy Shevchenko Link: https://patch.msgid.link/20251229144325.1252197-1-andriy.shevchenko@linux.intel.com [ Fix minor typo in the commit message. - Danilo ] Signed-off-by: Danilo Krummrich

PCI: Introduce pci_walk_bus_reverse(), for_each_pci_dev_reverse()

2025-11-04T03:27:40+00:00

PCI/TSM, the PCI core functionality for the PCIe TEE Device Interface Security Protocol (TDISP), has a need to walk all subordinate functions of a Device Security Manager (DSM) to setup a device security context. A DSM is physical function 0 of multi-function or SR-IOV device endpoint, or it is an upstream switch port. In error scenarios or when a TEE Security Manager (TSM) device is removed it needs to unwind all established DSM contexts. Introduce reverse versions of PCI device iteration helpers to mirror the setup path and ensure that dependent children are handled before parents. Cc: Greg Kroah-Hartman Reviewed-by: Jonathan Cameron Link: https://patch.msgid.link/20251031212902.2256310-4-dan.j.williams@intel.com Signed-off-by: Dan Williams

Merge tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2025-01-28T20:25:12+00:00

Pull driver core and debugfs updates from Greg KH: "Here is the big set of driver core and debugfs updates for 6.14-rc1. Included in here is a bunch of driver core, PCI, OF, and platform rust bindings (all acked by the different subsystem maintainers), hence the merge conflict with the rust tree, and some driver core api updates to mark things as const, which will also require some fixups due to new stuff coming in through other trees in this merge window. There are also a bunch of debugfs updates from Al, and there is at least one user that does have a regression with these, but Al is working on tracking down the fix for it. In my use (and everyone else's linux-next use), it does not seem like a big issue at the moment. Here's a short list of the things in here: - driver core rust bindings for PCI, platform, OF, and some i/o functions. We are almost at the "write a real driver in rust" stage now, depending on what you want to do. - misc device rust bindings and a sample driver to show how to use them - debugfs cleanups in the fs as well as the users of the fs api for places where drivers got it wrong or were unnecessarily doing things in complex ways. - driver core const work, making more of the api take const * for different parameters to make the rust bindings easier overall. - other small fixes and updates All of these have been in linux-next with all of the aforementioned merge conflicts, and the one debugfs issue, which looks to be resolved "soon"" * tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (95 commits) rust: device: Use as_char_ptr() to avoid explicit cast rust: device: Replace CString with CStr in property_present() devcoredump: Constify 'struct bin_attribute' devcoredump: Define 'struct bin_attribute' through macro rust: device: Add property_present() saner replacement for debugfs_rename() orangefs-debugfs: don't mess with ->d_name octeontx2: don't mess with ->d_parent or ->d_parent->d_name arm_scmi: don't mess with ->d_parent->d_name slub: don't mess with ->d_name sof-client-ipc-flood-test: don't mess with ->d_name qat: don't mess with ->d_name xhci: don't mess with ->d_iname mtu3: don't mess wiht ->d_iname greybus/camera - stop messing with ->d_iname mediatek: stop messing with ->d_iname netdevsim: don't embed file_operations into your structs b43legacy: make use of debugfs_get_aux() b43: stop embedding struct file_operations into their objects carl9170: stop embedding file_operations into their objects ...

driver core: Introduce device_iter_t for device iterating APIs

2025-01-10T14:26:12+00:00

There are several for_each APIs which has parameter with type below: int (*fn)(struct device *dev, void *data) They iterate over various device lists and call @fn() for each device with caller provided data @*data, and they usually need to modify @*data. Give the type an dedicated typedef with advantages shown below: typedef int (*device_iter_t)(struct device *dev, void *data) - Shorter API declarations and definitions - Prevent further for_each APIs from using bad parameter type So introduce device_iter_t and apply it to various existing APIs below: bus_for_each_dev() (class|driver)_for_each_device() device_for_each_child(_reverse|_reverse_from)(). Reviewed-by: Jonathan Cameron Signed-off-by: Zijun Hu Link: https://lore.kernel.org/r/20250105-class_fix-v6-7-3a2f1768d4d4@quicinc.com Signed-off-by: Greg Kroah-Hartman

driver core: Introduce an device matching API device_match_type()

2025-01-03T10:20:05+00:00

Introduce device_match_type() for purposes below: - Test if a device matches with a specified device type. - As argument of various device finding APIs to find a device with specified type. device_find_child() will use it to simplify operations later. Reviewed-by: Jonathan Cameron Signed-off-by: Zijun Hu Link: https://lore.kernel.org/r/20241224-const_dfc_done-v5-9-6623037414d4@quicinc.com Signed-off-by: Greg Kroah-Hartman

driver core: bus: add irq_get_affinity callback to bus_type

2024-12-23T15:17:23+00:00

Introducing a callback in struct bus_type so that a subsystem can hook up the getters directly. This approach avoids exposing random getters in any subsystems APIs. Acked-by: Bjorn Helgaas Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Reviewed-by: Ming Lei Acked-by: Greg Kroah-Hartman Signed-off-by: Daniel Wagner Link: https://lore.kernel.org/r/20241202-refactor-blk-affinity-helpers-v6-1-27211e9c2cd5@kernel.org Signed-off-by: Jens Axboe

drivers/base: Introduce device_match_t for device finding APIs

2024-09-03T10:48:51+00:00

There are several drivers/base APIs for finding a specific device, and they currently use the following good type for the @match parameter: int (*match)(struct device *dev, const void *data) Since these operations do not modify the caller-provided @*data, this type is worthy of a dedicated typedef: typedef int (*device_match_t)(struct device *dev, const void *data) Advantages of using device_match_t: - Shorter API declarations and definitions - Prevent further APIs from using a bad type for @match So introduce device_match_t and apply it to the existing (bus|class|driver|auxiliary)_find_device() APIs. Signed-off-by: Zijun Hu Link: https://lore.kernel.org/r/20240813-dev_match_api-v3-1-6c6878a99b9f@quicinc.com Signed-off-by: Greg Kroah-Hartman

driver core: have match() callback in struct bus_type take a const *

2024-07-03T13:16:54+00:00

In the match() callback, the struct device_driver * should not be changed, so change the function callback to be a const *. This is one step of many towards making the driver core safe to have struct device_driver in read-only memory. Because the match() callback is in all busses, all busses are modified to handle this properly. This does entail switching some container_of() calls to container_of_const() to properly handle the constant *. For some busses, like PCI and USB and HV, the const * is cast away in the match callback as those busses do want to modify those structures at this point in time (they have a local lock in the driver structure.) That will have to be changed in the future if they wish to have their struct device * in read-only-memory. Cc: Rafael J. Wysocki Reviewed-by: Alex Elder Acked-by: Sumit Garg Link: https://lore.kernel.org/r/2024070136-wrongdoer-busily-01e8@gregkh Signed-off-by: Greg Kroah-Hartman