[PATCH 00/11] kobject: Require explicit initialization of struct kobj_type::release

[Ian Rogers <irogers@google.com>]

Clang supports the 'require_explicit_initialization' attribute on struct
fields to enforce that the field is explicitly initialized when an
aggregate object is constructed, emitting -Wuninitialized-explicit-init
(enabled by default) if the field is omitted.

Following discussion at the Linux Plumbers Conference [1], this series
introduces __require_explicit_initialization in
include/linux/compiler_attributes.h and applies it to
struct kobj_type::release.

As Documentation/core-api/kobject.rst notes:
  "One important point cannot be overstated: every kobject must have a
  release() method, and the kobject must persist (in a consistent state)
  until that method is called. If these constraints are not met, the code
  is flawed."

Annotating struct kobj_type::release caught 30 struct kobj_type
definitions across the tree that omitted .release:
- Patches 2-10 fix 10 struct kobj_type definitions where dynamically
  allocated kobjects, ksets, or enclosing structures were either leaked on
  kobject_put() or freed prematurely before kobject release (risking a
  use-after-free when CONFIG_DEBUG_KOBJECT_RELEASE=y).
- Patch 11 annotates struct kobj_type::release with
  __require_explicit_initialization and explicitly sets .release = NULL
  (with explanatory comments) on the remaining legacy struct kobj_type
  definitions whose kobjects are static, per-CPU, or embedded in devm- or
  parent-managed structures.

[1] https://lpc.events/event/20/contributions/2392/

Ian Rogers (11):
  Compiler Attributes: Add __require_explicit_initialization macro
  powerpc/secvar: Add missing kobject release callback to secvar_ktype
  sh: sq: Add missing kobject release callback to ktype_percpu_entry
  cpufreq: Initialize kobj_type release callback in ondemand and
    conservative governors
  ACPI: CPPC: Free cpc_desc in kobject release callback
  dlm: Free dlm_ls in kobject release callback
  xen/sys-hypervisor: Add release callback to hyp_sysfs_kobj_type
  s390/sclp_mem: Allocate struct sclp_mem dynamically and add kobject
    release
  ubifs: sysfs: Use kset_create_and_add() for ubifs_kset
  drm/amdkfd: Free queue in procfs_queue_type kobject release callback
  kobject: Require explicit initialization of struct kobj_type::release

 Documentation/conf.py                         |  1 +
 arch/arm64/kernel/cpuinfo.c                   |  2 +
 arch/powerpc/kernel/secvar-sysfs.c            |  6 ++
 arch/sh/kernel/cpu/sh4/sq.c                   |  6 ++
 drivers/acpi/cppc_acpi.c                      | 39 +++++-----
 drivers/acpi/sysfs.c                          |  2 +
 drivers/cpufreq/cpufreq_conservative.c        |  5 +-
 drivers/cpufreq/cpufreq_governor.c            |  3 +-
 drivers/cpufreq/cpufreq_governor.h            |  1 +
 drivers/cpufreq/cpufreq_ondemand.c            |  5 +-
 drivers/dma/ioat/sysfs.c                      |  2 +
 drivers/gpu/drm/amd/amdgpu/amdgpu_xcp.c       |  4 +
 drivers/gpu/drm/amd/amdkfd/kfd_process.c      | 10 ++-
 drivers/gpu/drm/amd/amdkfd/kfd_queue.c        |  5 +-
 drivers/infiniband/hw/hfi1/sysfs.c            |  2 +
 drivers/infiniband/hw/usnic/usnic_ib_sysfs.c  |  2 +
 drivers/parisc/pdc_stable.c                   |  2 +
 drivers/power/supply/ab8500_fg.c              |  2 +
 drivers/s390/char/sclp_mem.c                  | 73 +++++++++----------
 drivers/soc/hisilicon/kunpeng_hccs.c          |  6 ++
 .../fbdev/omap2/omapfb/dss/display-sysfs.c    |  2 +
 .../fbdev/omap2/omapfb/dss/manager-sysfs.c    |  2 +
 .../fbdev/omap2/omapfb/dss/overlay-sysfs.c    |  2 +
 drivers/xen/sys-hypervisor.c                  |  6 ++
 fs/dlm/lockspace.c                            | 19 +++--
 fs/erofs/sysfs.c                              |  4 +
 fs/f2fs/sysfs.c                               |  6 ++
 fs/ocfs2/cluster/masklog.c                    |  2 +
 fs/ubifs/sysfs.c                              | 24 ++----
 include/linux/compiler_attributes.h           | 11 +++
 include/linux/kobject.h                       |  2 +-
 scripts/checkpatch.pl                         |  1 +
 tools/lib/python/kdoc/xforms_lists.py         |  1 +
 33 files changed, 170 insertions(+), 90 deletions(-)

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2.56.0.385.gd3acb90ef8-goog