rcu: Shut up spurious gcc uninitialized-variable warning

Because gcc doesn't realize that rcu_num_lvls must be strictly greater
than zero, some versions give a spurious warning about levelcnt[0] being
uninitialized in rcu_init_one().  This commit updates the condition on
the pre-existing panic() in order to educate gcc on this point.

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

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index c34422d..9b076b2 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3982,9 +3982,9 @@ static void __init rcu_init_one(struct rcu_state *rsp,
 
        BUILD_BUG_ON(MAX_RCU_LVLS > ARRAY_SIZE(buf));  /* Fix buf[] init! */
 
-       /* Silence gcc 4.8 warning about array index out of range. */
-       if (rcu_num_lvls > RCU_NUM_LVLS)
-               panic("rcu_init_one: rcu_num_lvls overflow");
+       /* Silence gcc 4.8 false positive about array index out of range. */
+       if (rcu_num_lvls <= 0 || rcu_num_lvls > RCU_NUM_LVLS)
+               panic("rcu_init_one: rcu_num_lvls out of range");
 
        /* Initialize the level-tracking arrays. */