Commit bae6076e authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Neeraj Upadhyay
Browse files

rcu/nocb: Remove SEGCBLIST_RCU_CORE 



RCU core can't be running anymore while in the middle of (de-)offloading
since this sort of transition now only applies to offline CPUs.

The SEGCBLIST_RCU_CORE state can therefore be removed.

Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Reviewed-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarNeeraj Upadhyay <neeraj.upadhyay@kernel.org>
parent df7c249a

include/linux/rcu_segcblist.h

+4 −5
Original line number Diff line number Diff line
@@ -185,11 +185,10 @@ struct rcu_cblist { 
 *  ----------------------------------------------------------------------------

 */

#define SEGCBLIST_ENABLED	BIT(0)

#define SEGCBLIST_RCU_CORE	BIT(1)

#define SEGCBLIST_LOCKING	BIT(2)

#define SEGCBLIST_KTHREAD_CB	BIT(3)

#define SEGCBLIST_KTHREAD_GP	BIT(4)

#define SEGCBLIST_OFFLOADED	BIT(5)

#define SEGCBLIST_LOCKING	BIT(1)

#define SEGCBLIST_KTHREAD_CB	BIT(2)

#define SEGCBLIST_KTHREAD_GP	BIT(3)

#define SEGCBLIST_OFFLOADED	BIT(4)



struct rcu_segcblist {

	struct rcu_head *head;

kernel/rcu/rcu_segcblist.h

+0 −9
Original line number Diff line number Diff line
@@ -95,15 +95,6 @@ static inline bool rcu_segcblist_is_offloaded(struct rcu_segcblist *rsclp) 
	return false;

}



static inline bool rcu_segcblist_completely_offloaded(struct rcu_segcblist *rsclp)

{

	if (IS_ENABLED(CONFIG_RCU_NOCB_CPU) &&

	    !rcu_segcblist_test_flags(rsclp, SEGCBLIST_RCU_CORE))

		return true;



	return false;

}



/*

 * Are all segments following the specified segment of the specified

 * rcu_segcblist structure empty of callbacks?  (The specified

kernel/rcu/tree.c

+0 −3
Original line number Diff line number Diff line
@@ -79,9 +79,6 @@ static void rcu_sr_normal_gp_cleanup_work(struct work_struct *); 


static DEFINE_PER_CPU_SHARED_ALIGNED(struct rcu_data, rcu_data) = {

	.gpwrap = true,

#ifdef CONFIG_RCU_NOCB_CPU

	.cblist.flags = SEGCBLIST_RCU_CORE,

#endif

};

static struct rcu_state rcu_state = {

	.level = { &rcu_state.node[0] },

kernel/rcu/tree_nocb.h

+0 −9
Original line number Diff line number Diff line
@@ -1060,7 +1060,6 @@ static int rcu_nocb_rdp_deoffload(struct rcu_data *rdp) 
	WARN_ON_ONCE(rcu_cblist_n_cbs(&rdp->nocb_bypass));

	WARN_ON_ONCE(rcu_segcblist_n_cbs(&rdp->cblist));



	rcu_segcblist_set_flags(cblist, SEGCBLIST_RCU_CORE);

	wake_gp = rdp_offload_toggle(rdp, false, flags);



	mutex_lock(&rdp_gp->nocb_gp_kthread_mutex);
@@ -1168,13 +1167,6 @@ static int rcu_nocb_rdp_offload(struct rcu_data *rdp) 
	swait_event_exclusive(rdp->nocb_state_wq,

			      rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_GP));



	/*

	 * All kthreads are ready to work, we can finally enable nocb bypass.

	 */

	rcu_nocb_lock_irqsave(rdp, flags);

	rcu_segcblist_clear_flags(cblist, SEGCBLIST_RCU_CORE);

	rcu_nocb_unlock_irqrestore(rdp, flags);



	return 0;

}
@@ -1350,7 +1342,6 @@ void __init rcu_init_nohz(void) 
			rcu_segcblist_init(&rdp->cblist);

		rcu_segcblist_offload(&rdp->cblist, true);

		rcu_segcblist_set_flags(&rdp->cblist, SEGCBLIST_KTHREAD_GP);

		rcu_segcblist_clear_flags(&rdp->cblist, SEGCBLIST_RCU_CORE);

	}

	rcu_organize_nocb_kthreads();

}