From 18390aeae7010ee56b132dcfb663ba362a099d99 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 22 Apr 2018 15:06:05 -0700 Subject: [PATCH] rcu: Make rcu_gp_cleanup() write only once to ->gp_flags At the end of rcu_gp_cleanup(), if another grace period is needed, but not via rcu_accelerate_cbs(), the ->gp_flags field is written twice, once when making the new grace-period request, and once when clearing all other types of requests. This commit therefore adds an else-clause to avoid this double write. Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 6ce82c009195..a9a4a260ea7d 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2117,8 +2117,9 @@ static void rcu_gp_cleanup(struct rcu_state *rsp) rsp->gp_req_activity = jiffies; trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gpnum), TPS("newreq")); + } else { + WRITE_ONCE(rsp->gp_flags, rsp->gp_flags & RCU_GP_FLAG_INIT); } - WRITE_ONCE(rsp->gp_flags, rsp->gp_flags & RCU_GP_FLAG_INIT); raw_spin_unlock_irq_rcu_node(rnp); }