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Commit 94d44776 authored by Jisheng Zhang's avatar Jisheng Zhang Committed by Paul E. McKenney
Browse files

rcu: Use rcu_gp_kthread_wake() to wake up grace period kthreads 



Commit abedf8e2 ("rcu: Use simple wait queues where possible in
rcutree") converts Tree RCU's wait queues to simple wait queues,
but it incorrectly reverts the commit 2aa792e6 ("rcu: Use
rcu_gp_kthread_wake() to wake up grace period kthreads").  This can
result in redundant self-wakeups.

This commit therefore replaces the simple wait-queue wakeups with
rcu_gp_kthread_wake(), thus avoiding the redundant wakeups.

Signed-off-by: default avatarJisheng Zhang <jszhang@marvell.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent bedc1969

kernel/rcu/tree.c

+2 −2
Original line number Diff line number Diff line
@@ -2344,7 +2344,7 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) 
	WARN_ON_ONCE(!rcu_gp_in_progress(rsp));

	WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);

	raw_spin_unlock_irqrestore_rcu_node(rcu_get_root(rsp), flags);

	swake_up(&rsp->gp_wq);  /* Memory barrier implied by swake_up() path. */

	rcu_gp_kthread_wake(rsp);

}



/*
@@ -2970,7 +2970,7 @@ static void force_quiescent_state(struct rcu_state *rsp) 
	}

	WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS);

	raw_spin_unlock_irqrestore_rcu_node(rnp_old, flags);

	swake_up(&rsp->gp_wq); /* Memory barrier implied by swake_up() path. */

	rcu_gp_kthread_wake(rsp);

}



/*