rcu: Improve comments for hotplug/suspend/hibernate functions (deb34f36) · Commits · jan.koester / Linux

kernel/rcu/tree.c

+37 −4

Original line number	Diff line number	Diff line
		@@ -3894,6 +3894,10 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp)
		raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
		}

		/*
		* Invoked early in the CPU-online process, when pretty much all
		* services are available. The incoming CPU is not present.
		*/
		int rcutree_prepare_cpu(unsigned int cpu)
		{
		struct rcu_state *rsp;
		@@ -3907,6 +3911,9 @@ int rcutree_prepare_cpu(unsigned int cpu)
		return 0;
		}

		/*
		* Update RCU priority boot kthread affinity for CPU-hotplug changes.
		*/
		static void rcutree_affinity_setting(unsigned int cpu, int outgoing)
		{
		struct rcu_data *rdp = per_cpu_ptr(rcu_state_p->rda, cpu);
		@@ -3914,6 +3921,10 @@ static void rcutree_affinity_setting(unsigned int cpu, int outgoing)
		rcu_boost_kthread_setaffinity(rdp->mynode, outgoing);
		}

		/*
		* Near the end of the CPU-online process. Pretty much all services
		* enabled, and the CPU is now very much alive.
		*/
		int rcutree_online_cpu(unsigned int cpu)
		{
		sync_sched_exp_online_cleanup(cpu);
		@@ -3921,13 +3932,19 @@ int rcutree_online_cpu(unsigned int cpu)
		return 0;
		}

		/*
		* Near the beginning of the process. The CPU is still very much alive
		* with pretty much all services enabled.
		*/
		int rcutree_offline_cpu(unsigned int cpu)
		{
		rcutree_affinity_setting(cpu, cpu);
		return 0;
		}


		/*
		* Near the end of the offline process. We do only tracing here.
		*/
		int rcutree_dying_cpu(unsigned int cpu)
		{
		struct rcu_state *rsp;
		@@ -3937,6 +3954,9 @@ int rcutree_dying_cpu(unsigned int cpu)
		return 0;
		}

		/*
		* The outgoing CPU is gone and we are running elsewhere.
		*/
		int rcutree_dead_cpu(unsigned int cpu)
		{
		struct rcu_state *rsp;
		@@ -3954,6 +3974,10 @@ int rcutree_dead_cpu(unsigned int cpu)
		* incoming CPUs are not allowed to use RCU read-side critical sections
		* until this function is called. Failing to observe this restriction
		* will result in lockdep splats.
		*
		* Note that this function is special in that it is invoked directly
		* from the incoming CPU rather than from the cpuhp_step mechanism.
		* This is because this function must be invoked at a precise location.
		*/
		void rcu_cpu_starting(unsigned int cpu)
		{
		@@ -3976,9 +4000,6 @@ void rcu_cpu_starting(unsigned int cpu)

		#ifdef CONFIG_HOTPLUG_CPU
		/*
		* The CPU is exiting the idle loop into the arch_cpu_idle_dead()
		* function. We now remove it from the rcu_node tree's ->qsmaskinit
		* bit masks.
		* The CPU is exiting the idle loop into the arch_cpu_idle_dead()
		* function. We now remove it from the rcu_node tree's ->qsmaskinit
		* bit masks.
		@@ -3997,6 +4018,14 @@ static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
		raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
		}

		/*
		* The outgoing function has no further need of RCU, so remove it from
		* the list of CPUs that RCU must track.
		*
		* Note that this function is special in that it is invoked directly
		* from the outgoing CPU rather than from the cpuhp_step mechanism.
		* This is because this function must be invoked at a precise location.
		*/
		void rcu_report_dead(unsigned int cpu)
		{
		struct rcu_state *rsp;
		@@ -4011,6 +4040,10 @@ void rcu_report_dead(unsigned int cpu)
		}
		#endif

		/*
		* On non-huge systems, use expedited RCU grace periods to make suspend
		* and hibernation run faster.
		*/
		static int rcu_pm_notify(struct notifier_block *self,
		unsigned long action, void *hcpu)
		{