netdev - [PATCH net-next v3 0/3] ice: lighter locking for PTP time reading

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Message-ID: <20240307222510.53654-1-mschmidt@redhat.com>
Date: Thu,  7 Mar 2024 23:25:07 +0100
From: Michal Schmidt <mschmidt@...hat.com>
To: intel-wired-lan@...ts.osuosl.org
Cc: netdev@...r.kernel.org,
	Jacob Keller <jacob.e.keller@...el.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Jiri Pirko <jiri@...nulli.us>,
	Jesse Brandeburg <jesse.brandeburg@...el.com>,
	Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>,
	Karol Kolacinski <karol.kolacinski@...el.com>
Subject: [PATCH net-next v3 0/3] ice: lighter locking for PTP time reading

This series removes the use of the heavy-weight PTP hardware semaphore
in the gettimex64 path. Instead, serialization of access to the time
register is done using a host-side spinlock. The timer hardware is
shared between PFs on the PCI adapter, so the spinlock must be shared
between ice_pf instances too.

Replacing the PTP hardware semaphore entirely with a mutex is also
possible and you can see it done in my git branch[1], but I am not
posting those patches yet to keep the scope of this series limited.

[1] https://gitlab.com/mschmidt2/linux/-/commits/ice-ptp-host-side-lock-9

v3:
 - Longer variable name ("a" -> "adapter").
 - Propagate xarray error in ice_adapter_get with ERR_PTR.
 - Added kernel-doc comments for ice_adapter_{get,put}.

v2:
 - Patch 1: Rely on xarray's own lock. (Suggested by Jiri Pirko)
 - Patch 2: Do not use *_irqsave with ptp_gltsyn_time_lock, as it's used
   only in process contexts.

Michal Schmidt (3):
  ice: add ice_adapter for shared data across PFs on the same NIC
  ice: avoid the PTP hardware semaphore in gettimex64 path
  ice: fold ice_ptp_read_time into ice_ptp_gettimex64

 drivers/net/ethernet/intel/ice/Makefile      |   3 +-
 drivers/net/ethernet/intel/ice/ice.h         |   2 +
 drivers/net/ethernet/intel/ice/ice_adapter.c | 109 +++++++++++++++++++
 drivers/net/ethernet/intel/ice/ice_adapter.h |  28 +++++
 drivers/net/ethernet/intel/ice/ice_main.c    |   8 ++
 drivers/net/ethernet/intel/ice/ice_ptp.c     |  33 +-----
 drivers/net/ethernet/intel/ice/ice_ptp_hw.c  |   3 +
 7 files changed, 156 insertions(+), 30 deletions(-)
 create mode 100644 drivers/net/ethernet/intel/ice/ice_adapter.c
 create mode 100644 drivers/net/ethernet/intel/ice/ice_adapter.h

-- 
2.43.2