Commit e2bd1682 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Uladzislau Rezki (Sony)
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rcu: Move rcu_report_exp_rdp() setting of ->cpu_no_qs.b.exp under lock 



This commit reduces the state space of rcu_report_exp_rdp() by moving
the setting of ->cpu_no_qs.b.exp under the rcu_node structure's ->lock.
The lock isn't really all that important here, given that this per-CPU
field is supposed to be written only by its CPU, but the disabling of
interrupts excludes things like rcu_exp_handler(), which also can write
to this same field.  Avoiding this sort of interleaved access reduces
the state space.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarUladzislau Rezki (Sony) <urezki@gmail.com>
parent d16e32f7

kernel/rcu/tree_exp.h

+1 −1
Original line number Diff line number Diff line
@@ -260,8 +260,8 @@ static void rcu_report_exp_rdp(struct rcu_data *rdp) 
	unsigned long flags;

	struct rcu_node *rnp = rdp->mynode;



	WRITE_ONCE(rdp->cpu_no_qs.b.exp, false);

	raw_spin_lock_irqsave_rcu_node(rnp, flags);

	WRITE_ONCE(rdp->cpu_no_qs.b.exp, false);

	rcu_report_exp_cpu_mult(rnp, flags, rdp->grpmask, true);

}