stop_machine: Provide RCU quiescent state in multi_cpu_stop() (366237e7) · Commits · 戴 / test

When multi_cpu_stop() loops waiting for other tasks, it can trigger an RCU CPU stall warning. This can be misleading because what is instead needed is information on whatever task is blocking multi_cpu_stop(). This commit therefore inserts an RCU quiescent state into the multi_cpu_stop() function's waitloop. Signed-off-by:

Paul E. McKenney <paulmck@kernel.org>

include/linux/rcutree.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -37,6 +37,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func);

		void rcu_barrier(void);
		bool rcu_eqs_special_set(int cpu);
		void rcu_momentary_dyntick_idle(void);
		unsigned long get_state_synchronize_rcu(void);
		void cond_synchronize_rcu(unsigned long oldstate);

kernel/rcu/tree.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -364,7 +364,7 @@ bool rcu_eqs_special_set(int cpu)
		*
		* The caller must have disabled interrupts and must not be idle.
		*/
		static void __maybe_unused rcu_momentary_dyntick_idle(void)
		void rcu_momentary_dyntick_idle(void)
		{
		int special;

kernel/stop_machine.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -233,6 +233,7 @@ static int multi_cpu_stop(void *data)
		*/
		touch_nmi_watchdog();
		}
		rcu_momentary_dyntick_idle();
		} while (curstate != MULTI_STOP_EXIT);

		local_irq_restore(flags);

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