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Commit b92db6cb authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Paul E. McKenney
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rcu: Rearrange locking in rcu_start_gp() 



If CPUs are to give prior notice of needed grace periods, it will be
necessary to invoke rcu_start_gp() without dropping the root rcu_node
structure's ->lock.  This commit takes a first step in this direction
by moving the release of this lock to the end of rcu_start_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 c0f4dfd4

kernel/rcutree.c

+2 −4
Original line number Diff line number Diff line
@@ -1521,16 +1521,14 @@ rcu_start_gp(struct rcu_state *rsp, unsigned long flags) 
		raw_spin_unlock_irqrestore(&rnp->lock, flags);

		return;

	}



	rsp->gp_flags = RCU_GP_FLAG_INIT;

	raw_spin_unlock(&rnp->lock); /* Interrupts remain disabled. */



	/* Ensure that CPU is aware of completion of last grace period. */

	rcu_process_gp_end(rsp, rdp);

	local_irq_restore(flags);

	__rcu_process_gp_end(rsp, rdp->mynode, rdp);



	/* Wake up rcu_gp_kthread() to start the grace period. */

	wake_up(&rsp->gp_wq);

	raw_spin_unlock_irqrestore(&rnp->lock, flags);

}



/*