kernel/linux.git/drivers/base/dd.c, branch v6.12.103

driver core: Use system_percpu_wq instead of system_wq

2026-07-24T14:10:53+00:00

[ Upstream commit fda8355f13ea3c0f9499acdeff3024995b474948 ] Commit 1137838865bf ("driver core: Use mod_delayed_work to prevent lost deferred probe work") added a use of system_wq, which is deprecated in favor of system_percpu_wq added by commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq"). An upcoming warning in the workqueue tree flags this with: workqueue: work func deferred_probe_timeout_work_func enqueued on deprecated workqueue. Use system_{percpu|dfl}_wq instead. Switch to system_percpu_wq to clear up the warning. Fixes: 1137838865bf ("driver core: Use mod_delayed_work to prevent lost deferred probe work") Signed-off-by: Nathan Chancellor Reviewed-by: Rafael J. Wysocki (Intel) Link: https://patch.msgid.link/20260601-driver-core-fix-system_wq-warning-v1-1-f9001a70ee25@kernel.org Signed-off-by: Danilo Krummrich Signed-off-by: Sasha Levin

driver core: Guard deferred probe timeout extension with delayed_work_pending()

2026-07-24T14:10:49+00:00

[ Upstream commit 557495bc879013c3d5e21d667e987e7ce3a514de ] mod_delayed_work() unconditionally queues the work even when it wasn't previously pending, which can fire the timeout prematurely or restart it after it already fired. Add a delayed_work_pending() guard to restore the originally intended semantics. Premature firing calls fw_devlink_drivers_done() before all built-in drivers have registered, causing fw_devlink to prematurely relax device links for suppliers whose drivers haven't loaded yet. Fixes: 1137838865bf ("driver core: Use mod_delayed_work to prevent lost deferred probe work") Tested-by: Geert Uytterhoeven Reviewed-by: Greg Kroah-Hartman Link: https://patch.msgid.link/20260525012340.3860581-2-dakr@kernel.org Signed-off-by: Danilo Krummrich Signed-off-by: Sasha Levin

driver core: Fix missing jiffies conversion in deferred_probe_extend_timeout()

2026-07-24T14:10:49+00:00

[ Upstream commit f9e6da99fe49277979798a1c3b9790ae10aaa18a ] mod_delayed_work() takes jiffies, not seconds. Thus, restore the dropped conversion. While at it, fix incorrect indentation. Fixes: 1137838865bf ("driver core: Use mod_delayed_work to prevent lost deferred probe work") Tested-by: Biju Das Tested-by: Geert Uytterhoeven Reviewed-by: Greg Kroah-Hartman Link: https://patch.msgid.link/20260525012340.3860581-1-dakr@kernel.org Signed-off-by: Danilo Krummrich Signed-off-by: Sasha Levin

driver core: Use mod_delayed_work to prevent lost deferred probe work

2026-07-24T14:10:48+00:00

[ Upstream commit 1137838865bfc9a7cd5869c1dc5c22aa45ec12c8 ] The deferred_probe_timeout_work may be permanently and unexpectedly canceled when deferred_probe_extend_timeout() executes concurrently. Starting with deferred_probe_timeout_work pending, the problem can occur after the following sequence: CPU0 CPU1 deferred_probe_extend_timeout -> cancel_delayed_work() => true deferred_probe_extend_timeout -> cancel_delayed_work() -> __cancel_work() -> try_grab_pending() -> schedule_delayed_work() -> queue_delayed_work_on() (Since the pending bit is grabbed, it just returns without queuing) -> set_work_pool_and_clear_pending() (This __cancel_work() returns false and the work will never be queued again) The root cause is that the WORK_STRUCT_PENDING_BIT of the work_struct is set temporarily in __cancel_work() (via try_grab_pending()). This transient state prevents the work_struct from being successfully queued by another CPU. To fix this, replace the original non-atomic cancel and schedule mechanism with mod_delayed_work(). This ensures the modification is handled atomically and guarantees that the work is not lost. Fixes: 2b28a1a84a0e ("driver core: Extend deferred probe timeout on driver registration") Signed-off-by: Zhang Yuwei Link: https://patch.msgid.link/20260410024448.387231-1-zhangyuwei20@huawei.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

driver core: Don't let a device probe until it's ready

2026-05-07T04:09:24+00:00

commit a2225b6e834a838ae3c93709760edc0a169eb2f2 upstream. The moment we link a "struct device" into the list of devices for the bus, it's possible probe can happen. This is because another thread can load the driver at any time and that can cause the device to probe. This has been seen in practice with a stack crawl that looks like this [1]: really_probe() __driver_probe_device() driver_probe_device() __driver_attach() bus_for_each_dev() driver_attach() bus_add_driver() driver_register() __platform_driver_register() init_module() [some module] do_one_initcall() do_init_module() load_module() __arm64_sys_finit_module() invoke_syscall() As a result of the above, it was seen that device_links_driver_bound() could be called for the device before "dev->fwnode->dev" was assigned. This prevented __fw_devlink_pickup_dangling_consumers() from being called which meant that other devices waiting on our driver's sub-nodes were stuck deferring forever. It's believed that this problem is showing up suddenly for two reasons: 1. Android has recently (last ~1 year) implemented an optimization to the order it loads modules [2]. When devices opt-in to this faster loading, modules are loaded one-after-the-other very quickly. This is unlike how other distributions do it. The reproduction of this problem has only been seen on devices that opt-in to Android's "parallel module loading". 2. Android devices typically opt-in to fw_devlink, and the most noticeable issue is the NULL "dev->fwnode->dev" in device_links_driver_bound(). fw_devlink is somewhat new code and also not in use by all Linux devices. Even though the specific symptom where "dev->fwnode->dev" wasn't assigned could be fixed by moving that assignment higher in device_add(), other parts of device_add() (like the call to device_pm_add()) are also important to run before probe. Only moving the "dev->fwnode->dev" assignment would likely fix the current symptoms but lead to difficult-to-debug problems in the future. Fix the problem by preventing probe until device_add() has run far enough that the device is ready to probe. If somehow we end up trying to probe before we're allowed, __driver_probe_device() will return -EPROBE_DEFER which will make certain the device is noticed. In the race condition that was seen with Android's faster module loading, we will temporarily add the device to the deferred list and then take it off immediately when device_add() probes the device. Instead of adding another flag to the bitfields already in "struct device", instead add a new "flags" field and use that. This allows us to freely change the bit from different thread without worrying about corrupting nearby bits (and means threads changing other bit won't corrupt us). [1] Captured on a machine running a downstream 6.6 kernel [2] https://cs.android.com/android/platform/superproject/main/+/main:system/core/libmodprobe/libmodprobe.cpp?q=LoadModulesParallel Cc: stable@vger.kernel.org Fixes: 2023c610dc54 ("Driver core: add new device to bus's list before probing") Reviewed-by: Alan Stern Reviewed-by: Rafael J. Wysocki (Intel) Reviewed-by: Danilo Krummrich Acked-by: Greg Kroah-Hartman Acked-by: Marek Szyprowski Signed-off-by: Douglas Anderson Link: https://patch.msgid.link/20260406162231.v5.1.Id750b0fbcc94f23ed04b7aecabcead688d0d8c17@changeid Signed-off-by: Danilo Krummrich Signed-off-by: Greg Kroah-Hartman

driver core: generalize driver_override in struct device

2026-04-02T11:09:25+00:00

[ Upstream commit cb3d1049f4ea77d5ad93f17d8ac1f2ed4da70501 ] 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 Stable-dep-of: 2b38efc05bf7 ("driver core: platform: use generic driver_override infrastructure") Signed-off-by: Sasha Levin

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

2026-02-16T16:09:13+00:00

This reverts commit cd0e0a76e40c2e77bcfc88291d00dca22b00158e which is commit dc23806a7c47ec5f1293aba407fb69519f976ee0 upstream. It causes boot regressions on some systems as all of the "fixes" for drivers are not properly backported yet. Once that is completed, only then can this be applied, if really necessary given the potential for explosions, perhaps we might want to wait a few -rc releases first... Cc: Danilo Krummrich Cc: Rafael J. Wysocki (Intel) Cc: Danilo Krummrich Cc: Gui-Dong Han Cc: Qiu-ji Chen Reported-by: Mark Brown Link: https://lore.kernel.org/r/7dfd0e63-a725-4fac-b2a0-f2e621d99d1b@sirena.org.uk Signed-off-by: Greg Kroah-Hartman

driver core: enforce device_lock for driver_match_device()

2026-02-16T09:18:43+00:00

commit dc23806a7c47ec5f1293aba407fb69519f976ee0 upstream. 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 Signed-off-by: Gui-Dong Han Fixes: 49b420a13ff9 ("driver core: check bus->match without holding device lock") Reviewed-by: Danilo Krummrich Reviewed-by: Greg Kroah-Hartman Reviewed-by: Rafael J. Wysocki (Intel) Link: https://patch.msgid.link/20260113162843.12712-1-hanguidong02@gmail.com Signed-off-by: Danilo Krummrich Signed-off-by: Greg Kroah-Hartman

driver core: introduce device_set_driver() helper

2025-05-02T05:59:28+00:00

commit 04d3e5461c1f5cf8eec964ab64948ebed826e95e upstream. In preparation to closing a race when reading driver pointer in dev_uevent() code, instead of setting device->driver pointer directly introduce device_set_driver() helper. Signed-off-by: Dmitry Torokhov Reviewed-by: Masami Hiramatsu (Google) Link: https://lore.kernel.org/r/20250311052417.1846985-2-dmitry.torokhov@gmail.com Signed-off-by: Greg Kroah-Hartman

Merge tag 'driver-core-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2024-09-27T15:48:37+00:00

Pull driver core updates from Greg KH: "Here is a small set of patches for the driver core code for 6.12-rc1. This set is the one that caused the most delay on my side, due to lots of last-minute reports of problems in the async shutdown feature that was added. In the end, I've reverted all of the patches in that series so we are back to "normal" and the patch set is being reworked for the next merge window. Other than the async shutdown patches that were reverted, included in here are: - minor driver core cleanups - minor driver core bus and class api cleanups and simplifications for some callbacks - some const markings of structures - other even more minor cleanups All of these, including the last minute reverts, have been in linux-next, but all of the reports of problems in linux-next were before the reverts happened. After the reverts, all is good" * tag 'driver-core-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (32 commits) Revert "driver core: don't always lock parent in shutdown" Revert "driver core: separate function to shutdown one device" Revert "driver core: shut down devices asynchronously" Revert "nvme-pci: Make driver prefer asynchronous shutdown" Revert "driver core: fix async device shutdown hang" driver core: fix async device shutdown hang driver core: attribute_container: Remove unused functions driver core: Trivially simplify ((struct device_private *)curr)->device->p to @curr devres: Correclty strip percpu address space of devm_free_percpu() argument driver core: Make parameter check consistent for API cluster device_(for_each|find)_child() bus: fsl-mc: make fsl_mc_bus_type const nvme-pci: Make driver prefer asynchronous shutdown driver core: shut down devices asynchronously driver core: separate function to shutdown one device driver core: don't always lock parent in shutdown platform: Make platform_bus_type constant driver core: class: Check namespace relevant parameters in class_register() driver:base:core: Adding a "Return:" line in comment for device_link_add() drivers/base: Introduce device_match_t for device finding APIs firmware_loader: Block path traversal ...