Commit 8b425aa8 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Paul E. McKenney
Browse files

rcu: Rename n_nocb_gp_requests to need_future_gp 



CPUs going idle need to be able to indicate their need for future grace
periods.  A mechanism for doing this already exists for no-callbacks
CPUs, so the idea is to re-use that mechanism.  This commit therefore
moves the ->n_nocb_gp_requests field of the rcu_node structure out from
under the CONFIG_RCU_NOCB_CPU #ifdef and renames it to ->need_future_gp.

Signed-off-by: default avatarPaul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent b8462084

kernel/rcutree.h

+2 −2
Original line number Diff line number Diff line
@@ -194,9 +194,9 @@ struct rcu_node { 
#ifdef CONFIG_RCU_NOCB_CPU

	wait_queue_head_t nocb_gp_wq[2];

				/* Place for rcu_nocb_kthread() to wait GP. */

	int n_nocb_gp_requests[2];

				/* Counts of upcoming no-CB GP requests. */

#endif /* #ifdef CONFIG_RCU_NOCB_CPU */

	int need_future_gp[2];

				/* Counts of upcoming no-CB GP requests. */

	raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp;

} ____cacheline_internodealigned_in_smp;

kernel/rcutree_plugin.h

+9 −9
Original line number Diff line number Diff line
@@ -2018,7 +2018,7 @@ static int rcu_nocb_needs_gp(struct rcu_state *rsp) 
{

	struct rcu_node *rnp = rcu_get_root(rsp);



	return rnp->n_nocb_gp_requests[(ACCESS_ONCE(rnp->completed) + 1) & 0x1];

	return rnp->need_future_gp[(ACCESS_ONCE(rnp->completed) + 1) & 0x1];

}



/*
@@ -2032,8 +2032,8 @@ static int rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp) 
	int needmore;



	wake_up_all(&rnp->nocb_gp_wq[c & 0x1]);

	rnp->n_nocb_gp_requests[c & 0x1] = 0;

	needmore = rnp->n_nocb_gp_requests[(c + 1) & 0x1];

	rnp->need_future_gp[c & 0x1] = 0;

	needmore = rnp->need_future_gp[(c + 1) & 0x1];

	trace_rcu_future_grace_period(rsp->name, rnp->gpnum, rnp->completed,

				      c, rnp->level, rnp->grplo, rnp->grphi,

				      needmore ? "CleanupMore" : "Cleanup");
@@ -2041,7 +2041,7 @@ static int rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp) 
}



/*

 * Set the root rcu_node structure's ->n_nocb_gp_requests field

 * Set the root rcu_node structure's ->need_future_gp field

 * based on the sum of those of all rcu_node structures.  This does

 * double-count the root rcu_node structure's requests, but this

 * is necessary to handle the possibility of a rcu_nocb_kthread()
@@ -2050,7 +2050,7 @@ static int rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp) 
 */

static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq)

{

	rnp->n_nocb_gp_requests[(rnp->completed + 1) & 0x1] += nrq;

	rnp->need_future_gp[(rnp->completed + 1) & 0x1] += nrq;

}



static void rcu_init_one_nocb(struct rcu_node *rnp)
@@ -2181,7 +2181,7 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp) 
	c = rnp->completed + 2;



	/* Count our request for a grace period. */

	rnp->n_nocb_gp_requests[c & 0x1]++;

	rnp->need_future_gp[c & 0x1]++;

	trace_rcu_future_grace_period(rdp->rsp->name, rnp->gpnum,

				      rnp->completed, c, rnp->level,

				      rnp->grplo, rnp->grphi, "Startleaf");
@@ -2225,10 +2225,10 @@ static void rcu_nocb_wait_gp(struct rcu_data *rdp) 
			 * Adjust counters accordingly and start the

			 * needed grace period.

			 */

			rnp->n_nocb_gp_requests[c & 0x1]--;

			rnp->need_future_gp[c & 0x1]--;

			c = rnp_root->completed + 1;

			rnp->n_nocb_gp_requests[c & 0x1]++;

			rnp_root->n_nocb_gp_requests[c & 0x1]++;

			rnp->need_future_gp[c & 0x1]++;

			rnp_root->need_future_gp[c & 0x1]++;

			trace_rcu_future_grace_period(rdp->rsp->name,

						      rnp->gpnum,

						      rnp->completed,

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