From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Tue, 12 Jan 2016 00:29:29 +0000 (-0800)
Subject: rcu: Force boolean subscript for expedited stall warnings
X-Git-Tag: v4.7-rc1~196^2^2^2~7
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=ec3833ed02ae6ef2a933ece9de7cbab0c64c699e;p=linux.git

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 62e73e0a929f..64c2e3288551 100644
--- 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)]);
 			}