On Sun, Oct 14, 2018 at 7:26 PM [off-list ref] wrote:

From: Frank Rowand <redacted>

Add checks to (1) overlay apply process and (2) memory freeing
triggered by overlay release.  The checks are intended to detect
possible memory leaks and invalid overlays.

The checks revealed bugs in existing code.  Fixed the bugs.

While fixing bugs, noted other issues, which are fixed in
separate patches.

*****  Powerpc folks: I was not able to test the patches that
*****  directly impact Powerpc systems that use dynamic
*****  devicetree.  Please review that code carefully and
*****  test.  The specific patches are: 03/16, 04/16, 07/16

FPGA folks:

  I made the validation checks that should result in an
  invalid live devicetree report "ERROR" and cause the overlay apply
  to fail.

  I made the memory leak validation tests report "WARNING" and allow
  the overlay apply to complete successfully.  Please let me know
  if you encounter the warnings.  There are at least two paths
  forward to deal with the cases that trigger the warning: (1) change
  the warning to an error and fail the overlay apply, or (2) find a
  way to detect the potential memory leaks and free the memory
  appropriately.

I reran my FPGA testing.  The strings are fixed, no longer NULL.  I
have functionality back, my test passes now.  I'm seeing the intended
warnings about any properties added to existing nodes.  That includes
warnings about added symbols.  Below is a simplified part to show some
of what I'm seeing.

By the way my testing is all using Pantelis' DT overlay configfs interface.

root@arria10:~# ./apply-static-region.sh

Applying dtbo: socfpga_arria10_socdk_sdmmc_ghrd_ovl_ext_cfg.dtb

[ 1821.088640] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property:
/soc/base_fpga_region/ranges
[ 1821.103307] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property:
/soc/base_fpga_region/external-fpga-config
[ 1821.117359] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property:
/soc/base_fpga_region/clocks
[ 1821.130130] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property:
/soc/base_fpga_region/clock-names
[ 1821.143449] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property: /__symbols__/clk_0
[ 1821.155357] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property: /__symbols__/ILC
[ 1821.167074] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property:
/__symbols__/freeze_controller_0
[ 1821.180171] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property:
/__symbols__/sysid_qsys_0
[ 1821.192662] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property: /__symbols__/led_pio
[ 1821.204720] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property: /__symbols__/button_pio
[ 1821.217034] OF: overlay: WARNING: add_changeset_property(), memory
leak will occur if overlay removed.  Property: /__symbols__/dipsw_pio
[ 1821.231977] of-fpga-region soc:base_fpga_region:fpga_pr_region0:
FPGA Region probed
[ 1821.240144] altera_freeze_br ff200450.freeze_controller: fpga
bridge [freeze] registered

root@arria10:~# ./apply-static-region.sh root@arria10:~# rmdir
/sys/kernel/config/device-tree/overlays/1-socfpga_arria10_socdk_sdmmc_ghrd_ovl_ext_cfg.dtb

[ 1823.805564] OF: ERROR: memory leak - destroy cset entry: attach
overlay node /soc/base_fpga_region/clk_0 with refcount 2

Alan


Alan

ALL people:

  The validations do _not_ address another major concern I have with
  releasing overlays, which is use after free errors.

Changes since v2:

  - 13/18: Use continue to reduce indentation in find_dup_cset_node_entry()
    and find_dup_cset_prop()

Changes since v1:

  - move patch 16/16 to 17/18
  - move patch 15/16 to 18/18
  - new patch 15/18
  - new patch 16/18

  - 05/18: add_changeset_node() header comment: incorrect comment for @target

  - 18/18: add same fix for of_parse_phandle_with_args()
  - 18/18: add same fix for of_parse_phandle_with_args_map()

Frank Rowand (18):
  of: overlay: add tests to validate kfrees from overlay removal
  of: overlay: add missing of_node_put() after add new node to changeset
  of: overlay: add missing of_node_get() in __of_attach_node_sysfs
  powerpc/pseries: add of_node_put() in dlpar_detach_node()
  of: overlay: use prop add changeset entry for property in new nodes
  of: overlay: do not duplicate properties from overlay for new nodes
  of: dynamic: change type of of_{at,de}tach_node() to void
  of: overlay: reorder fields in struct fragment
  of: overlay: validate overlay properties #address-cells and
    #size-cells
  of: overlay: make all pr_debug() and pr_err() messages unique
  of: overlay: test case of two fragments adding same node
  of: overlay: check prevents multiple fragments add or delete same node
  of: overlay: check prevents multiple fragments touching same property
  of: unittest: remove unused of_unittest_apply_overlay() argument
  of: overlay: set node fields from properties when add new overlay node
  of: unittest: allow base devicetree to have symbol metadata
  of: unittest: find overlays[] entry by name instead of index
  of: unittest: initialize args before calling of_*parse_*()

 arch/powerpc/platforms/pseries/dlpar.c             |  15 +-
 arch/powerpc/platforms/pseries/reconfig.c          |   6 +-
 drivers/of/dynamic.c                               |  68 +++--
 drivers/of/kobj.c                                  |   4 +-
 drivers/of/overlay.c                               | 298 ++++++++++++++++-----
 drivers/of/unittest-data/Makefile                  |   2 +
 .../of/unittest-data/overlay_bad_add_dup_node.dts  |  28 ++
 .../of/unittest-data/overlay_bad_add_dup_prop.dts  |  24 ++
 drivers/of/unittest-data/overlay_base.dts          |   1 +
 drivers/of/unittest.c                              |  96 +++++--
 include/linux/of.h                                 |  19 +-
 11 files changed, 439 insertions(+), 122 deletions(-)
 create mode 100644 drivers/of/unittest-data/overlay_bad_add_dup_node.dts
 create mode 100644 drivers/of/unittest-data/overlay_bad_add_dup_prop.dts

--
Frank Rowand [off-list ref]