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: Paul E. McKenney <[email protected]> Cc: Frederic Weisbecker <[email protected]> --- kernel/rcu/tree_exp.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 581e88d39542d..5c4ea66cc00dd 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -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); } -- 2.40.1
