4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paul E. McKenney <paul...@linux.vnet.ibm.com>

commit ec3833ed02ae6ef2a933ece9de7cbab0c64c699e upstream.

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 <paul...@linux.vnet.ibm.com>
Cc: "Rantala, Tommi" <tommi.t.rant...@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 kernel/rcu/tree.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3817,7 +3817,7 @@ static void synchronize_sched_expedited_
                                        continue;
                                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)]);
                        }


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