rcu: Allow for smp_call_function() running callbacks from idle (806f04e9) · Commits · 戴 / test

kernel/rcu/tree.c

+19 −6

Original line number	Original line	Diff line number	Diff line
	@@ -418,16 +418,23 @@ void rcu_momentary_dyntick_idle(void)
	EXPORT_SYMBOL_GPL(rcu_momentary_dyntick_idle);		EXPORT_SYMBOL_GPL(rcu_momentary_dyntick_idle);

	/**		/**
	* rcu_is_cpu_rrupt_from_idle - see if interrupted from idle		* rcu_is_cpu_rrupt_from_idle - see if 'interrupted' from idle
	*		*
	* If the current CPU is idle and running at a first-level (not nested)		* If the current CPU is idle and running at a first-level (not nested)
	* interrupt from idle, return true. The caller must have at least		* interrupt, or directly, from idle, return true.
	* disabled preemption.		*
			* The caller must have at least disabled IRQs.
	*/		*/
	static int rcu_is_cpu_rrupt_from_idle(void)		static int rcu_is_cpu_rrupt_from_idle(void)
	{		{
	/* Called only from within the scheduling-clock interrupt */		long nesting;
	lockdep_assert_in_irq();
			/*
			* Usually called from the tick; but also used from smp_function_call()
			* for expedited grace periods. This latter can result in running from
			* the idle task, instead of an actual IPI.
			*/
			lockdep_assert_irqs_disabled();

	/* Check for counter underflows */		/* Check for counter underflows */
	RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) < 0,		RCU_LOCKDEP_WARN(__this_cpu_read(rcu_data.dynticks_nesting) < 0,
	@@ -436,9 +443,15 @@ static int rcu_is_cpu_rrupt_from_idle(void)
	"RCU dynticks_nmi_nesting counter underflow/zero!");		"RCU dynticks_nmi_nesting counter underflow/zero!");

	/* Are we at first interrupt nesting level? */		/* Are we at first interrupt nesting level? */
	if (__this_cpu_read(rcu_data.dynticks_nmi_nesting) != 1)		nesting = __this_cpu_read(rcu_data.dynticks_nmi_nesting);
			if (nesting > 1)
	return false;		return false;

			/*
			* If we're not in an interrupt, we must be in the idle task!
			*/
			WARN_ON_ONCE(!nesting && !is_idle_task(current));

	/* Does CPU appear to be idle from an RCU standpoint? */		/* Does CPU appear to be idle from an RCU standpoint? */
	return __this_cpu_read(rcu_data.dynticks_nesting) == 0;		return __this_cpu_read(rcu_data.dynticks_nesting) == 0;
	}		}

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