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[tip/core/rcu,18/23] rcu: Adjust for unconditional ->completed assignment

Message ID 1348166900-18716-18-git-send-email-paulmck@linux.vnet.ibm.com
State Accepted
Commit 25d30cf4250f74e5ceb35f8f39739782408db633
Headers show

Commit Message

Paul E. McKenney Sept. 20, 2012, 6:48 p.m. UTC 
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

Now that the rcu_node structures' ->completed fields are unconditionally
assigned at grace-period cleanup time, they should already have the
correct value for the new grace period at grace-period initialization
time.  This commit therefore inserts a WARN_ON_ONCE() to verify this
invariant.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
---
 kernel/rcutree.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
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Patch

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 5cb003d..71ae31b 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1078,6 +1078,7 @@  static int rcu_gp_init(struct rcu_state *rsp)
 		rcu_preempt_check_blocked_tasks(rnp);
 		rnp->qsmask = rnp->qsmaskinit;
 		rnp->gpnum = rsp->gpnum;
+		WARN_ON_ONCE(rnp->completed != rsp->completed);
 		rnp->completed = rsp->completed;
 		if (rnp == rdp->mynode)
 			rcu_start_gp_per_cpu(rsp, rnp, rdp);
@@ -2775,7 +2776,8 @@  static void __init rcu_init_one(struct rcu_state *rsp,
 			raw_spin_lock_init(&rnp->fqslock);
 			lockdep_set_class_and_name(&rnp->fqslock,
 						   &rcu_fqs_class[i], fqs[i]);
-			rnp->gpnum = 0;
+			rnp->gpnum = rsp->gpnum;
+			rnp->completed = rsp->completed;
 			rnp->qsmask = 0;
 			rnp->qsmaskinit = 0;
 			rnp->grplo = j * cpustride;