[PATCH v2 0/2] Update the watchdog period according to real CPU frequency

[Yicong Yang <yangyicong@huawei.com>]

From: Yicong Yang <yangyicong@hisilicon.com>

watchdog perf needs architecture to provide method for converting the watchdog
thresh to counter period. For arm64 we're using the max CPU frequency for
doing the conversion which is from cpufreq driver. But some cpufreq driver
are registered lately, for example cppc_cpufreq will be registered at late
initcall which is after the initialization of watchdog perf (initialized in
armv8_pmuv3 of device initcall). In such case the period of watchdog will not
be accurate enough. Fix this by registering a cpufreq notifier and update the
watchdog period once the cpufreq driver is initialized.

Change since v1:
- Handle the theoretical race condition and other comments from Doug, thanks
Link: https://lore.kernel.org/all/20250307021811.46981-1-yangyicong@huawei.com/

Yicong Yang (2):
  watchdog/perf: Provide function for adjusting the event period
  arm64/watchdog_hld: Add a cpufreq notifier for update watchdog thresh

 arch/arm64/kernel/watchdog_hld.c | 58 ++++++++++++++++++++++++++++++++
 include/linux/nmi.h              |  2 ++
 kernel/watchdog_perf.c           | 23 +++++++++++++
 3 files changed, 83 insertions(+)

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2.24.0