From 9de68394a61528d40f575c3e6719cc75c56f62c3 Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Mon, 2 Mar 2026 01:25:44 +0100 Subject: Revert "driver core: enforce device_lock for driver_match_device()" 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 --- include/linux/device/bus.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/device') diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h index 99c3c83ea520..63de5f053c33 100644 --- a/include/linux/device/bus.h +++ b/include/linux/device/bus.h @@ -35,6 +35,8 @@ struct fwnode_handle; * otherwise. It may also return error code if determining that * the driver supports the device is not possible. In case of * -EPROBE_DEFER it will queue the device for deferred probing. + * Note: This callback may be invoked with or without the device + * lock held. * @uevent: Called when a device is added, removed, or a few other things * that generate uevents to add the environment variables. * @probe: Called when a new device or driver add to this bus, and callback -- cgit v1.2.3 From 10f874dc92b3f3bf96470d997bdf157b289c9d4c Mon Sep 17 00:00:00 2001 From: Heiner Kallweit Date: Sun, 1 Mar 2026 13:31:56 +0100 Subject: driver core: make struct class groups members constant arrays Constify the groups arrays, allowing to assign constant arrays. Signed-off-by: Heiner Kallweit Link: https://patch.msgid.link/7ff56b07-09ca-4948-b98f-5bd37ceef21e@gmail.com Signed-off-by: Greg Kroah-Hartman --- include/linux/device/class.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/device') diff --git a/include/linux/device/class.h b/include/linux/device/class.h index 65880e60c720..2079239a5aa5 100644 --- a/include/linux/device/class.h +++ b/include/linux/device/class.h @@ -50,8 +50,8 @@ struct fwnode_handle; struct class { const char *name; - const struct attribute_group **class_groups; - const struct attribute_group **dev_groups; + const struct attribute_group *const *class_groups; + const struct attribute_group *const *dev_groups; int (*dev_uevent)(const struct device *dev, struct kobj_uevent_env *env); char *(*devnode)(const struct device *dev, umode_t *mode); -- cgit v1.2.3 From cb3d1049f4ea77d5ad93f17d8ac1f2ed4da70501 Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Tue, 3 Mar 2026 12:53:18 +0100 Subject: driver core: generalize driver_override in struct device 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 --- include/linux/device/bus.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/device') diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h index 63de5f053c33..c1b463cd6464 100644 --- a/include/linux/device/bus.h +++ b/include/linux/device/bus.h @@ -65,6 +65,9 @@ struct fwnode_handle; * this bus. * @pm: Power management operations of this bus, callback the specific * device driver's pm-ops. + * @driver_override: Set to true if this bus supports the driver_override + * mechanism, which allows userspace to force a specific + * driver to bind to a device via a sysfs attribute. * @need_parent_lock: When probing or removing a device on this bus, the * device core should lock the device's parent. * @@ -106,6 +109,7 @@ struct bus_type { const struct dev_pm_ops *pm; + bool driver_override; bool need_parent_lock; }; -- cgit v1.2.3 From e3b2cf6e5dba416a03152f299d99982dfe1e861d Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 1 Apr 2026 12:15:58 +0200 Subject: kernfs: pass struct ns_common instead of const void * for namespace tags kernfs has historically used const void * to pass around namespace tags used for directory-level namespace filtering. The only current user of this is sysfs network namespace tagging where struct net pointers are cast to void *. Replace all const void * namespace parameters with const struct ns_common * throughout the kernfs, sysfs, and kobject namespace layers. This includes the kobj_ns_type_operations callbacks, kobject_namespace(), and all sysfs/kernfs APIs that accept or return namespace tags. Passing struct ns_common is needed because various codepaths require access to the underlying namespace. A struct ns_common can always be converted back to the concrete namespace type (e.g., struct net) via container_of() or to_ns_common() in the reverse direction. This is a preparatory change for switching to ns_id-based directory iteration to prevent a KASLR pointer leak through the current use of raw namespace pointers as hash seeds and comparison keys. Signed-off-by: Christian Brauner --- include/linux/device/class.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/linux/device') diff --git a/include/linux/device/class.h b/include/linux/device/class.h index 65880e60c720..021da0d61796 100644 --- a/include/linux/device/class.h +++ b/include/linux/device/class.h @@ -62,7 +62,7 @@ struct class { int (*shutdown_pre)(struct device *dev); const struct kobj_ns_type_operations *ns_type; - const void *(*namespace)(const struct device *dev); + const struct ns_common *(*namespace)(const struct device *dev); void (*get_ownership)(const struct device *dev, kuid_t *uid, kgid_t *gid); @@ -180,9 +180,9 @@ struct class_attribute { struct class_attribute class_attr_##_name = __ATTR_WO(_name) int __must_check class_create_file_ns(const struct class *class, const struct class_attribute *attr, - const void *ns); + const struct ns_common *ns); void class_remove_file_ns(const struct class *class, const struct class_attribute *attr, - const void *ns); + const struct ns_common *ns); static inline int __must_check class_create_file(const struct class *class, const struct class_attribute *attr) -- cgit v1.2.3