[PATCH v11 00/10] ref_tracker: add ability to register a debugfs file for a ref_tracker_dir

[Jeff Layton]

More CI reports [1]. This time it showed what I consider to be an
existing bug in the i915 driver. It can call ref_tracker_dir_init() more
than once on the same dir object, which could cause reference tracking
objects to leak.

The first patch in the series ensures that this doesn't happen. The rest
is basically identical to v10 aside from a small format cleanup.

[1]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_148490v6/index.html

Signed-off-by: Jeff Layton <jlayton at kernel.org>
---
Changes in v11:
- don't call ref_tracker_dir_init() more than once for same i915 objects
- use %llx in format for net_cookie in symlink name
- Link to v10: https://lore.kernel.org/r/20250527-reftrack-dbgfs-v10-0-dc55f7705691@kernel.org

Changes in v10:
- drop the i915 symlink patch
- Link to v9: https://lore.kernel.org/r/20250509-reftrack-dbgfs-v9-0-8ab888a4524d@kernel.org

Changes in v9:
- fix typo in ref_tracker_dir_init() kerneldoc header
- Link to v8: https://lore.kernel.org/r/20250507-reftrack-dbgfs-v8-0-607717d3bb98@kernel.org

Changes in v8:
- fix up compiler warnings that the KTR warned about
- ensure builds with CONFIG_DEBUG_FS=n and CONFIG_REF_TRACKER=y work
- Link to v7: https://lore.kernel.org/r/20250505-reftrack-dbgfs-v7-0-f78c5d97bcca@kernel.org

Changes in v7:
- include net->net_cookie in netns symlink name
- add __ostream_printf to ref_tracker_dir_symlink() stub function
- remove unneeded #include of seq_file.h
- Link to v6: https://lore.kernel.org/r/20250430-reftrack-dbgfs-v6-0-867c29aff03a@kernel.org

Changes in v6:
- clean up kerneldoc comment for ref_tracker_dir_debugfs()
- add missing stub function for ref_tracker_dir_symlink()
- temporary __maybe_unused on ref_tracker_dir_seq_print() to silence compiler warning
- Link to v5: https://lore.kernel.org/r/20250428-reftrack-dbgfs-v5-0-1cbbdf2038bd@kernel.org

Changes in v5:
- add class string to each ref_tracker_dir
- auto-register debugfs file for every tracker in ref_tracker_dir_init
- add function to allow adding a symlink for each tracker
- add patches to create symlinks for netns's and i915 entries
- change output format to print class@%p instead of name@%p
- eliminate the name field in ref_tracker_dir
- fix off-by-one bug when NULL terminating name string
- Link to v4: https://lore.kernel.org/r/20250418-reftrack-dbgfs-v4-0-5ca5c7899544@kernel.org

Changes in v4:
- Drop patch to widen ref_tracker_dir_.name, use NAME_MAX+1 (256) instead since this only affects dentry name
- Link to v3: https://lore.kernel.org/r/20250417-reftrack-dbgfs-v3-0-c3159428c8fb@kernel.org

Changes in v3:
- don't overwrite dir->name in ref_tracker_dir_debugfs
- define REF_TRACKER_NAMESZ and use it when setting name
- Link to v2: https://lore.kernel.org/r/20250415-reftrack-dbgfs-v2-0-b18c4abd122f@kernel.org

Changes in v2:
- Add patch to do %pK -> %p conversion in ref_tracker.c
- Pass in output function to pr_ostream() instead of if statement
- Widen ref_tracker_dir.name to 64 bytes to accomodate unique names
- Eliminate error handling with debugfs manipulation
- Incorporate pointer value into netdev name
- Link to v1: https://lore.kernel.org/r/20250414-reftrack-dbgfs-v1-0-f03585832203@kernel.org

---
Jeff Layton (10):
      i915: only initialize struct ref_tracker_dir once
      ref_tracker: don't use %pK in pr_ostream() output
      ref_tracker: add a top level debugfs directory for ref_tracker
      ref_tracker: have callers pass output function to pr_ostream()
      ref_tracker: add a static classname string to each ref_tracker_dir
      ref_tracker: allow pr_ostream() to print directly to a seq_file
      ref_tracker: automatically register a file in debugfs for a ref_tracker_dir
      ref_tracker: add a way to create a symlink to the ref_tracker_dir debugfs file
      net: add symlinks to ref_tracker_dir for netns
      ref_tracker: eliminate the ref_tracker_dir name field

 drivers/gpu/drm/display/drm_dp_tunnel.c |   2 +-
 drivers/gpu/drm/i915/intel_runtime_pm.c |   4 +-
 drivers/gpu/drm/i915/intel_wakeref.c    |   3 +-
 include/linux/ref_tracker.h             |  58 +++++++++-
 lib/ref_tracker.c                       | 190 +++++++++++++++++++++++++++++---
 net/core/dev.c                          |   2 +-
 net/core/net_namespace.c                |  34 +++++-
 7 files changed, 267 insertions(+), 26 deletions(-)
---
base-commit: fefff2755f2aa4125dce2a1edfe7e545c7c621f2
change-id: 20250413-reftrack-dbgfs-3767b303e2fa

Best regards,
-- 
Jeff Layton <jlayton at kernel.org>