[PATCH v4 0/3] keepalive bugfixes

[Uday Shankar]

While reviewing the Linux KATO implementation in an attempt to better
understand the current NVMe Keep Alive specification, we found a
few issues in the host implementation that could contribute to spurious
Keep Alive timeouts being detected by controllers.

Changes v3-v4 (https://lore.kernel.org/linux-nvme/20230518183311.3224326-1-ushankar@purestorage.com/):
- Patch 1: fix style, improve readability, include helper from patch 3
- Patch 2: refactor to remove need for WRITE_ONCE/barriers
- Patch 3: fix comment style, move helper to patch 1

Changes v2-v3 (https://lore.kernel.org/linux-nvme/20230424232225.1975793-1-ushankar@purestorage.com/):
- Patch 3: add a warning log line for long keepalive RTT

Changes v1-v2 (https://lore.kernel.org/linux-nvme/20230417225558.2890062-1-ushankar@purestorage.com/):
- Patch 2: fix indentation, set start_time even when stats disabled

Uday Shankar (3):
  nvme: double KA polling frequency to avoid KATO with TBKAS on
  nvme: check IO start time when deciding to defer KA
  nvme: improve handling of long keep alives

 drivers/nvme/host/core.c | 46 +++++++++++++++++++++++++++++++++++++---
 drivers/nvme/host/nvme.h |  4 ++--
 2 files changed, 45 insertions(+), 5 deletions(-)

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2.25.1