Commit-ID: 665f08f1ce9cf608a9435e11d66f55be4e72540a
Gitweb: https://git.kernel.org/tip/665f08f1ce9cf608a9435e11d66f55be4e72540a
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Thu, 19 Apr 2018 12:23:34 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Tue, 15 May 2018 10:30:48 -0700
rcu: Make rcu_start_this_gp() check for out-of-range requests
If rcu_start_this_gp() is invoked with a requested grace period more
than three in the future, then either the ->need_future_gp[] array
needs to be bigger or the caller needs to be repaired. This commit
therefore adds a WARN_ON_ONCE() checking for this condition.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Tested-by: Nicholas Piggin <npiggin@xxxxxxxxx>
---
kernel/rcu/tree.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index d3c769502929..07bccb1f0c87 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1698,6 +1698,8 @@ static bool rcu_start_this_gp(struct rcu_node *rnp, struct rcu_data *rdp,
for (rnp_root = rnp; 1; rnp_root = rnp_root->parent) {
if (rnp_root != rnp)
raw_spin_lock_rcu_node(rnp_root);
+ WARN_ON_ONCE(ULONG_CMP_LT(rnp_root->gpnum +
+ need_future_gp_mask(), c));
if (need_future_gp_element(rnp_root, c) ||
ULONG_CMP_GE(rnp_root->gpnum, c) ||
(rnp != rnp_root &&
--
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