[PATCH] rcu: Avoid kthread_stop on invalid pointer if rcutorture reader startup fails

rcu_torture_init kmallocs the array of reader threads, then creates each
one with kthread_run, cleaning up with rcu_torture_cleanup if this fails.
rcu_torture_cleanup calls kthread_stop on any non-NULL pointer in the
array; however, any readers after the one that failed to start up will have
invalid pointers, not null pointers.  Avoid this by using kzalloc instead.

Signed-off-by: Josh Triplett <josh@freedesktop.org>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/rcutorture.c

@@ -780,7 +780,7 @@ rcu_torture_init(void)
 		writer_task = NULL;
 		goto unwind;
 	}
-	reader_tasks = kmalloc(nrealreaders * sizeof(reader_tasks[0]),
+	reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
 			       GFP_KERNEL);
 	if (reader_tasks == NULL) {
 		VERBOSE_PRINTK_ERRSTRING("out of memory");