rcu: Force boolean subscript for expedited stall warnings

The cpu_online() function can return values other than 0 and 1, which
can result in subscript overflow when applied to a two-element array.
This commit allows for this behavior by using "!!" on the return value
from cpu_online() when used as a subscript.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 62e73e0..64c2e32 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3808,7 +3808,7 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
                                ndetected++;
                                rdp = per_cpu_ptr(rsp->rda, cpu);
                                pr_cont(" %d-%c%c%c", cpu,
-                                       "O."[cpu_online(cpu)],
+                                       "O."[!!cpu_online(cpu)],
                                        "o."[!!(rdp->grpmask & rnp->expmaskinit)],
                                        "N."[!!(rdp->grpmask & rnp->expmaskinitnext)]);
                        }