From: Neeraj Upadhyay Date: Fri, 29 Mar 2019 11:27:08 +0000 (+0530) Subject: rcu: Correctly unlock root node in rcu_check_gp_start_stall() X-Git-Tag: v5.3-rc1~204^2^2^2^3~7 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3ae976a7e3e87438b8439a01aeb79d4866b1c444;p=thirdparty%2Fkernel%2Flinux.git 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 Reviewed-by: Mukesh Ojha Signed-off-by: Paul E. McKenney --- diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index f65a73a973235..065183391f759 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; }