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Commit 37a18447 authored by qctecmdr's avatar qctecmdr Committed by Gerrit - the friendly Code Review server
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Merge "rcu: Allow only one expedited GP to run concurrently with wakeups"

parents a2eda956 beb2ec8f

kernel/rcu/tree_exp.h

+6 −6
Original line number Diff line number Diff line
@@ -595,14 +595,14 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s) 
	struct rcu_node *rnp;



	synchronize_sched_expedited_wait(rsp);

	rcu_exp_gp_seq_end(rsp);

	trace_rcu_exp_grace_period(rsp->name, s, TPS("end"));



	/*

	 * Switch over to wakeup mode, allowing the next GP, but -only- the

	 * next GP, to proceed.

	/* Switch over to wakeup mode, allowing the next GP to proceed.

	 * End the previous grace period only after acquiring the mutex

	 * to ensure that only one GP runs concurrently with wakeups.

	 */

	mutex_lock(&rsp->exp_wake_mutex);

	rcu_exp_gp_seq_end(rsp);

	trace_rcu_exp_grace_period(rcu_state.name, s, TPS("end"));



	rcu_for_each_node_breadth_first(rsp, rnp) {

		if (ULONG_CMP_LT(READ_ONCE(rnp->exp_seq_rq), s)) {
@@ -613,7 +613,7 @@ static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s) 
			spin_unlock(&rnp->exp_lock);

		}

		smp_mb(); /* All above changes before wakeup. */

		wake_up_all(&rnp->exp_wq[rcu_seq_ctr(rsp->expedited_sequence) & 0x3]);

		wake_up_all(&rnp->exp_wq[rcu_seq_ctr(s) & 0x3]);

	}

	trace_rcu_exp_grace_period(rsp->name, s, TPS("endwake"));

	mutex_unlock(&rsp->exp_wake_mutex);