rcu: Clear request other than RCU_GP_FLAG_INIT at GP end

Once the grace period has ended, any RCU_GP_FLAG_FQS requests are
irrelevant:  The grace period has ended, so there is no longer any
point in forcing quiescent states in order to try to make it end sooner.
This commit therefore causes rcu_gp_cleanup() to clear any bits other
than RCU_GP_FLAG_INIT from ->gp_flags at the end of the grace period.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Nicholas Piggin <npiggin@gmail.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index c7b1e6b2a3da..25dbbc753fef 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2181,6 +2181,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
                                        READ_ONCE(rsp->gpnum),
                                        TPS("newreq"));
         }
+        WRITE_ONCE(rsp->gp_flags, rsp->gp_flags & RCU_GP_FLAG_INIT);
         raw_spin_unlock_irq_rcu_node(rnp);
 }