[PATCH net-next v6 0/6] ptp: Support for multiple filtered timestamp event queue readers

[Xabier Marquiegui <reibax@gmail.com>]

On systems with multiple timestamp event channels, there can be scenarios
where multiple userspace readers want to access the timestamping data for
various purposes.

One such example is wanting to use a pps out for time synchronization, and
wanting to timestamp external events with the synchronized time base 
simultaneously.

Timestmp event consumers on the other hand, are often interested in a
subset of the available timestamp channels. linuxptp ts2phc, for example,
is not happy if more than one timestamping channel is active on the device
it is reading from.

Linked lists are introduced to support multiple timestamp event queue
consumers, and timestamp event channel filters through IOCTLs, as well as
a debugfs interface to do some simple verifications.

Xabier Marquiegui (6):
  posix-clock: introduce posix_clock_context concept
  ptp: Replace timestamp event queue with linked list
  ptp: support multiple timestamp event readers
  ptp: support event queue reader channel masks
  ptp: add debugfs interface to see applied channel masks
  ptp: add testptp mask test

 drivers/ptp/ptp_chardev.c                   | 129 ++++++++++++++++----
 drivers/ptp/ptp_clock.c                     |  45 ++++++-
 drivers/ptp/ptp_private.h                   |  28 +++--
 drivers/ptp/ptp_sysfs.c                     |  13 +-
 include/linux/posix-clock.h                 |  35 ++++--
 include/uapi/linux/ptp_clock.h              |   2 +
 kernel/time/posix-clock.c                   |  36 ++++--
 tools/testing/selftests/ptp/ptpchmaskfmt.sh |  14 +++
 tools/testing/selftests/ptp/testptp.c       |  19 ++-
 9 files changed, 261 insertions(+), 60 deletions(-)
 create mode 100644 tools/testing/selftests/ptp/ptpchmaskfmt.sh

Signed-off-by: Xabier Marquiegui <reibax@gmail.com>
Suggested-by: Richard Cochran <richardcochran@gmail.com>
Suggested-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
---
v6:
  - correct commit message
  - correct coding style
v5: https://lore.kernel.org/netdev/cover.1696804243.git.reibax@gmail.com/
  - fix spelling on commit message
  - fix memory leak on ptp_open
v4: https://lore.kernel.org/netdev/cover.1696511486.git.reibax@gmail.com/
  - split modifications in different patches for improved organization
  - rename posix_clock_user to posix_clock_context
  - remove unnecessary flush_users clock operation
  - remove unnecessary tests
  - simpler queue clean procedure
  - fix/clean comment lines
  - simplified release procedures
  - filter modifications exclusive to currently open instance for
    simplicity and security
  - expand mask to 2048 channels
  - make more secure and simple: mask is only applied to the testptp
    instance. Use debugfs to verify effects.
v3: https://lore.kernel.org/netdev/20230928133544.3642650-1-reibax@gmail.com/
  - add this patchset overview file
  - fix use of safe and non safe linked lists for loops
  - introduce new posix_clock private_data and ida object ids for better
    dicrimination of timestamp consumers
  - safer resource release procedures
  - filter application by object id, aided by process id
  - friendlier testptp implementation of event queue channel filters
v2: https://lore.kernel.org/netdev/20230912220217.2008895-1-reibax@gmail.com/
  - fix ptp_poll() return value
  - Style changes to comform to checkpatch strict suggestions
  - more coherent ptp_read error exit routines
  - fix testptp compilation error: unknown type name 'pid_t'
  - rename mask variable for easier code traceability
  - more detailed commit message with two examples
v1: https://lore.kernel.org/netdev/20230906104754.1324412-2-reibax@gmail.com/
---