Re: [RFC PATCH v2 16/20] rcu: Make RCU dynticks counter size configurable
From: Valentin Schneider <vschneid@redhat.com>
Date: 2023-07-21 08:18:50
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On 20/07/23 17:30, Valentin Schneider wrote:
quoted hunk ↗ jump to hunk
index bdd7eadb33d8f..1ff2aab24e964 100644--- a/kernel/rcu/Kconfig +++ b/kernel/rcu/Kconfig@@ -332,4 +332,37 @@ config RCU_DOUBLE_CHECK_CB_TIME Say Y here if you need tighter callback-limit enforcement. Say N here if you are unsure. +config RCU_DYNTICKS_RANGE_BEGIN + int + depends on !RCU_EXPERT + default 31 if !CONTEXT_TRACKING_WORK
You'll note that this should be 30 really, because the lower *2* bits are taken by the context state (CONTEXT_GUEST has a value of 3). This highlights the fragile part of this: the Kconfig values are hardcoded, but they depend on CT_STATE_SIZE, CONTEXT_MASK and CONTEXT_WORK_MAX. The static_assert() will at least capture any misconfiguration, but having that enforced by the actual Kconfig ranges would be less awkward. Do we currently have a way of e.g. making a Kconfig file depend on and use values generated by a C header?