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Commit 8e9aa8f0 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Ingo Molnar
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rcu: Simplify association of forced quiescent states with grace periods 



The force_quiescent_state() function also took a snapshot
of the ->completed field, which was as obnoxious as it was in
rcu_sched_qs() and friends.  So snapshot ->gpnum-1.

Also, since the dyntick_record_completed() and
dyntick_recall_completed() functions are now simple assignments
that are independent of CONFIG_NO_HZ, and since their names are
now misleading, get rid of them.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <12580941042308-git-send-email->
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent b32e9eb6

kernel/rcutree.c

+3 −24
Original line number Original line Diff line number Diff line
@@ -178,28 +178,8 @@ static struct rcu_node *rcu_get_root(struct rcu_state *rsp) 
	return &rsp->node[0];

	return &rsp->node[0];

}

}





/*

 * Record the specified "completed" value, which is later used to validate

 * dynticks counter manipulations and CPU-offline checks.  Specify

 * "rsp->completed - 1" to unconditionally invalidate any future dynticks

 * manipulations and CPU-offline checks.  Such invalidation is useful at

 * the beginning of a grace period.

 */

static void dyntick_record_completed(struct rcu_state *rsp, long comp)

{

	rsp->completed_fqs = comp;

}



#ifdef CONFIG_SMP

#ifdef CONFIG_SMP





/*

 * Recall the previously recorded value of the completion for dynticks.

 */

static long dyntick_recall_completed(struct rcu_state *rsp)

{

	return rsp->completed_fqs;

}



/*

/*

 * If the specified CPU is offline, tell the caller that it is in

 * If the specified CPU is offline, tell the caller that it is in

 * a quiescent state.  Otherwise, whack it with a reschedule IPI.

 * a quiescent state.  Otherwise, whack it with a reschedule IPI.
@@ -702,7 +682,6 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) 
	rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */

	rsp->signaled = RCU_GP_INIT; /* Hold off force_quiescent_state. */

	rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;

	rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;

	record_gp_stall_check_time(rsp);

	record_gp_stall_check_time(rsp);

	dyntick_record_completed(rsp, rsp->completed - 1);





	/* Special-case the common single-level case. */

	/* Special-case the common single-level case. */

	if (NUM_RCU_NODES == 1) {

	if (NUM_RCU_NODES == 1) {
@@ -1214,7 +1193,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) 
		goto unlock_ret; /* no emergency and done recently. */

		goto unlock_ret; /* no emergency and done recently. */

	rsp->n_force_qs++;

	rsp->n_force_qs++;

	spin_lock(&rnp->lock);

	spin_lock(&rnp->lock);

	lastcomp = rsp->completed;

	lastcomp = rsp->gpnum - 1;

	signaled = rsp->signaled;

	signaled = rsp->signaled;

	rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;

	rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS;

	if (lastcomp == rsp->gpnum) {

	if (lastcomp == rsp->gpnum) {
@@ -1248,7 +1227,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) 
		if (lastcomp == rsp->completed &&

		if (lastcomp == rsp->completed &&

		    rsp->signaled == signaled) {

		    rsp->signaled == signaled) {

			rsp->signaled = RCU_FORCE_QS;

			rsp->signaled = RCU_FORCE_QS;

			dyntick_record_completed(rsp, lastcomp);

			rsp->completed_fqs = lastcomp;

			forcenow = signaled == RCU_SAVE_COMPLETED;

			forcenow = signaled == RCU_SAVE_COMPLETED;

		}

		}

		spin_unlock(&rnp->lock);

		spin_unlock(&rnp->lock);
@@ -1259,7 +1238,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) 
	case RCU_FORCE_QS:

	case RCU_FORCE_QS:





		/* Check dyntick-idle state, send IPI to laggarts. */

		/* Check dyntick-idle state, send IPI to laggarts. */

		if (rcu_process_dyntick(rsp, dyntick_recall_completed(rsp),

		if (rcu_process_dyntick(rsp, rsp->completed_fqs,

					rcu_implicit_dynticks_qs))

					rcu_implicit_dynticks_qs))

			goto unlock_ret;

			goto unlock_ret;