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 <[email protected]> --- 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 && -- 2.5.2
