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rcu: Make rcu_start_this_gp() check for out-of-range requests

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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@linux.vnet.ibm.com>
Tested-by: Nicholas Piggin <npiggin@gmail.com>
This commit is contained in:
Paul E. McKenney 2018-04-19 12:23:34 -07:00
parent 360e0da67e
commit 665f08f1ce
1 changed files with 2 additions and 0 deletions
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2
kernel/rcu/tree.c
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@ -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 &&