In preparation for adding new fields to 'struct device_private' fix up
existing kernel-doc warnings in this header file of the form:
Warning: drivers/base/base.h:59 struct member 'subsys' not described in
'subsys_private'
Warning: drivers/base/base.h:59 struct member 'devices_kset' not described
in 'subsys_private'
Warning: drivers/base/base.h:59 struct member 'interfaces' not described in
'subsys_private'
Warning: drivers/base/base.h:59 struct member 'mutex' not described in
'subsys_private'
...which are simple replacements of " - " with ": ".
Add new descriptions for these previously undescribed fields:
Warning: drivers/base/base.h:58 struct member 'drivers_autoprobe' not
described in 'subsys_private'
Warning: drivers/base/base.h:117 struct member 'deferred_probe_reason' not
described in 'device_private'
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/20260303000207.1836586-3-dan.j.williams@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In the current implementation driver_match_device() expects the device
lock to be held, while driver_match_device_locked() acquires the device
lock.
By convention it should be the other way around, hence swap the name of
both functions.
Fixes: dc23806a7c ("driver core: enforce device_lock for driver_match_device()")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Gui-Dong Han <hanguidong02@gmail.com>
Link: https://patch.msgid.link/20260131014211.12841-1-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Currently, driver_match_device() is called from three sites. One site
(__device_attach_driver) holds device_lock(dev), but the other two
(bind_store and __driver_attach) do not. This inconsistency means that
bus match() callbacks are not guaranteed to be called with the lock
held.
Fix this by introducing driver_match_device_locked(), which guarantees
holding the device lock using a scoped guard. Replace the unlocked calls
in bind_store() and __driver_attach() with this new helper. Also add a
lock assertion to driver_match_device() to enforce this guarantee.
This consistency also fixes a known race condition. The driver_override
implementation relies on the device_lock, so the missing lock led to the
use-after-free (UAF) reported in Bugzilla for buses using this field.
Stress testing the two newly locked paths for 24 hours with
CONFIG_PROVE_LOCKING and CONFIG_LOCKDEP enabled showed no UAF recurrence
and no lockdep warnings.
Cc: stable@vger.kernel.org
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220789
Suggested-by: Qiu-ji Chen <chenqiuji666@gmail.com>
Signed-off-by: Gui-Dong Han <hanguidong02@gmail.com>
Fixes: 49b420a13f ("driver core: check bus->match without holding device lock")
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Link: https://patch.msgid.link/20260113162843.12712-1-hanguidong02@gmail.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
In C dev_get_drvdata() has specific requirements under which it is valid
to access the returned pointer. That is, drivers have to ensure that
(1) for the duration the returned pointer is accessed the driver is
bound and remains to be bound to the corresponding device,
(2) the returned void * is treated according to the driver's private
data type, i.e. according to what has been passed to
dev_set_drvdata().
In Rust, (1) can be ensured by simply requiring the Bound device
context, i.e. provide the drvdata() method for Device<Bound> only.
For (2) we would usually make the device type generic over the driver
type, e.g. Device<T: Driver>, where <T as Driver>::Data is the type of
the driver's private data.
However, a device does not have a driver type known at compile time and
may be bound to multiple drivers throughout its lifetime.
Hence, in order to be able to provide a safe accessor for the driver's
device private data, we have to do the type check on runtime.
This is achieved by letting a driver assert the expected type, which is
then compared to a type hash stored in struct device_private when
dev_set_drvdata() is called.
Example:
// `dev` is a `&Device<Bound>`.
let data = dev.drvdata::<SampleDriver>()?;
There are two aspects to note:
(1) Technically, the same check could be achieved by comparing the
struct device_driver pointer of struct device with the struct
device_driver pointer of the driver struct (e.g. struct
pci_driver).
However, this would - in addition the pointer comparison - require
to tie back the private driver data type to the struct
device_driver pointer of the driver struct to prove correctness.
Besides that, accessing the driver struct (stored in the module
structure) isn't trivial and would result into horrible code and
API ergonomics.
(2) Having a direct accessor to the driver's private data is not
commonly required (at least in Rust): Bus callback methods already
provide access to the driver's device private data through a &self
argument, while other driver entry points such as IRQs,
workqueues, timers, IOCTLs, etc. have their own private data with
separate ownership and lifetime.
In other words, a driver's device private data is only relevant
for driver model contexts (such a file private is only relevant
for file contexts).
Having that said, the motivation for accessing the driver's device
private data with Device<Bound>::drvdata() are interactions between
drivers. For instance, when an auxiliary driver calls back into its
parent, the parent has to be capable to derive its private data from the
corresponding device (i.e. the parent of the auxiliary device).
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ * Remove unnecessary `const _: ()` block,
* rename type_id_{store,match}() to {set,match}_type_id(),
* assert size_of::<bindings::driver_type>() >= size_of::<TypeId>(),
* add missing check in case Device::drvdata() is called from probe().
- Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Device links with DL_FLAG_SYNC_STATE_ONLY should not affect system
suspend and resume, and functions like device_reorder_to_tail() and
device_link_add() don't try to reorder the consumers with that flag.
However, dpm_wait_for_consumers() and dpm_wait_for_suppliers() don't
check thas flag before triggering dpm_wait(), leading to potential hang
during suspend/resume.
This can be reproduced on MT8186 Corsola Chromebook with devicetree like:
usb-a-connector {
compatible = "usb-a-connector";
port {
usb_a_con: endpoint {
remote-endpoint = <&usb_hs>;
};
};
};
usb_host {
compatible = "mediatek,mt8186-xhci", "mediatek,mtk-xhci";
port {
usb_hs: endpoint {
remote-endpoint = <&usb_a_con>;
};
};
};
In this case, the two nodes form a cycle and a SYNC_STATE_ONLY devlink
between usb_host (supplier) and usb-a-connector (consumer) is created.
Address this by exporting device_link_flag_is_sync_state_only() and
making dpm_wait_for_consumers() and dpm_wait_for_suppliers() use it
when deciding if dpm_wait() should be called.
Fixes: 05ef983e0d ("driver core: Add device link support for SYNC_STATE_ONLY flag")
Signed-off-by: Pin-yen Lin <treapking@chromium.org>
Link: https://patch.msgid.link/20250926102320.4053167-1-treapking@chromium.org
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Add separate macros for walking links to suppliers and consumers of a
device to help device links users to avoid exposing the internals of
struct dev_links_info in their code and possible coding mistakes related
to that.
Accordingly, use the new macros to replace open-coded device links list
walks in the core power management code.
No intentional functional impact.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/1944671.tdWV9SEqCh@rafael.j.wysocki
If userspace reads "uevent" device attribute at the same time as another
threads unbinds the device from its driver, change to dev->driver from a
valid pointer to NULL may result in crash. Fix this by using READ_ONCE()
when fetching the pointer, and take bus' drivers klist lock to make sure
driver instance will not disappear while we access it.
Use WRITE_ONCE() when setting the driver pointer to ensure there is no
tearing.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20250311052417.1846985-3-dmitry.torokhov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add code to allow asynchronous shutdown of devices, ensuring that each
device is shut down before its parents & suppliers.
Only devices with drivers that have async_shutdown_enable enabled will be
shut down asynchronously.
This can dramatically reduce system shutdown/reboot time on systems that
have multiple devices that take many seconds to shut down (like certain
NVMe drives). On one system tested, the shutdown time went from 11 minutes
without this patch to 55 seconds with the patch.
Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: David Jeffery <djeffery@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Tested-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20240822202805.6379-4-stuart.w.hayes@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 <rafael@kernel.org>
Reviewed-by: Alex Elder <elder@kernel.org>
Acked-by: Sumit Garg <sumit.garg@linaro.org>
Link: https://lore.kernel.org/r/2024070136-wrongdoer-busily-01e8@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
