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authorPeter Zijlstra <peterz@infradead.org>2023-01-12 20:44:04 +0100
committerIngo Molnar <mingo@kernel.org>2023-01-13 11:48:18 +0100
commit0e985e9d22864e29d5d2b3d909ad15134d7f6d46 (patch)
tree710fbac5e48688b81dec48394c2007de459252ce /drivers/cpuidle
parent26388a7c353f7b1d3fd8a6df6452fa9773193155 (diff)
cpuidle: Add comments about noinstr/__cpuidle usage
Add a few words on noinstr / __cpuidle usage. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20230112195542.397238052@infradead.org
Diffstat (limited to 'drivers/cpuidle')
-rw-r--r--drivers/cpuidle/cpuidle.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 73f7d8b763c6..500d1720421e 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -252,6 +252,18 @@ noinstr int cpuidle_enter_state(struct cpuidle_device *dev,
instrumentation_begin();
}
+ /*
+ * NOTE!!
+ *
+ * For cpuidle_state::enter() methods that do *NOT* set
+ * CPUIDLE_FLAG_RCU_IDLE RCU will be disabled here and these functions
+ * must be marked either noinstr or __cpuidle.
+ *
+ * For cpuidle_state::enter() methods that *DO* set
+ * CPUIDLE_FLAG_RCU_IDLE this isn't required, but they must mark the
+ * function calling ct_cpuidle_enter() as noinstr/__cpuidle and all
+ * functions called within the RCU-idle region.
+ */
entered_state = target_state->enter(dev, drv, index);
if (WARN_ONCE(!irqs_disabled(), "%ps leaked IRQ state", target_state->enter))