Messages in this thread | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 00/21] driver core: bus: remove private "backpointer" from struct bus_type | Date | Wed, 8 Feb 2023 12:13:09 +0100 |
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In the quest to make all struct bus_type constant in the kernel, allowing them to move into read-only memory, this patch series goes through the steps in getting rid of the "private" pointer in struct bus_type. It does so primarily by relying on the already-present list of subsystems in the driver core and looking up the struct bus_type from that list when needed, or looking up the private structure from the bus pointer, depending on what is needed.
Overall, more lines of code are added, but we now have the additional safely that the internal subsystem private type is properly reference counted. We "got away" with not incrementing reference counts because we relied on the caller of functions to have a valid reference when calling into the core. That's not really the proper way to handle reference counts, so as part of the conversion, reference counts are now correctly handled.
There are still some remaining steps to be able to have bus_type be constant everywhere in the kernel, but this series is a great first step and is the "hard part" of the work. The rest involves changing the callback sysfs file functions and handling the dev_root pointer properly. Those changes will be forthcoming after these as they involve lots more minor driver changes all over the kernel.
This has been build-tested by the 0-day bot for a while, and is being used by me right now to send this series out, so it "works for me!"
This series is based against my current driver-core-next branch that is in linux-next.
Greg Kroah-Hartman (21): driver core: add local subsys_get and subsys_put functions driver core: bus: implement bus_get/put() without the private pointer driver core: bus: constantify the bus_find_* functions driver core: bus: convert bus_create/remove_file to be constant driver core: bus: sysfs function cleanups driver core: bus: bus_add/probe/remove_device() cleanups driver core: bus: bus_register/unregister() cleanups driver core: bus: subsys_interface_register/unregister() cleanups driver core: bus: bus_get_kset() cleanup driver core: bus: bus_register/unregister_notifier() cleanups driver core: bus: bus_add/remove_driver() cleanups driver core: bus: bus iterator cleanups driver core: bus: clean up bus_sort_breadthfirst() driver core: move driver_find() to bus.c driver core: bus: clean up driver_find() driver core: create bus_is_registered() driver core: remove private pointer from struct bus_type driver core: bus: constify bus_register/unregister_notifier() driver core: bus: constify bus_get_kset() driver core: bus: constify some internal functions driver core: bus: constify bus_unregister()
drivers/base/base.h | 14 ++ drivers/base/bus.c | 491 ++++++++++++++++++++++++++----------- drivers/base/driver.c | 29 +-- include/linux/device/bus.h | 37 ++- 4 files changed, 375 insertions(+), 196 deletions(-)
-- 2.39.1
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