From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Thu, 19 Apr 2018 16:40:32 +0000 (-0700)
Subject: rcu: Clear request other than RCU_GP_FLAG_INIT at GP end
X-Git-Tag: v4.18-rc1~169^2~1^2^3~8
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a824a287f6eaec65f1cf7aedfd5f6b69d2d3858f;p=thirdparty%2Fkernel%2Flinux.git

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>
---

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index c7b1e6b2a3dae..25dbbc753fef1 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);
 }