Commit-ID: 3ae976a7e3e87438b8439a01aeb79d4866b1c444
Gitweb: https://git.kernel.org/tip/3ae976a7e3e87438b8439a01aeb79d4866b1c444
Author: Neeraj Upadhyay <neeraju@xxxxxxxxxxxxxx>
AuthorDate: Fri, 29 Mar 2019 16:57:08 +0530
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxx>
CommitDate: Tue, 28 May 2019 09:02:57 -0700
rcu: Correctly unlock root node in rcu_check_gp_start_stall()
On systems whose rcu_node tree has only one node, the
rcu_check_gp_start_stall() function's values of rnp and rnp_root will
be identical. In this case, it clearly does not make sense to release
both rnp->lock and rnp_root->lock, but that is exactly what this function
does in the last early exit. This commit therefore unlocks only rnp->lock
when rnp and rnp_root are equal.
Signed-off-by: Neeraj Upadhyay <neeraju@xxxxxxxxxxxxxx>
Reviewed-by: Mukesh Ojha <mojha@xxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxx>
---
kernel/rcu/tree_stall.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index f65a73a97323..065183391f75 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -630,7 +630,9 @@ static void rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp,
time_before(j, rcu_state.gp_req_activity + gpssdelay) ||
time_before(j, rcu_state.gp_activity + gpssdelay) ||
atomic_xchg(&warned, 1)) {
- raw_spin_unlock_rcu_node(rnp_root); /* irqs remain disabled. */
+ if (rnp_root != rnp)
+ /* irqs remain disabled. */
+ raw_spin_unlock_rcu_node(rnp_root);
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
return;
}
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