[tip:core/rcu] rcu: Shut up spurious gcc uninitialized-variable warning

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Commit-ID:  3eaaaf6cd6d7fbaf552cc543ccb93d7da81f43ec
Gitweb:     http://git.kernel.org/tip/3eaaaf6cd6d7fbaf552cc543ccb93d7da81f43ec
Author:     Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 9 Mar 2015 16:51:17 -0700
Committer:  Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Wed, 27 May 2015 12:59:02 -0700

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@xxxxxxxxxxxxxxxxxx>
---
 kernel/rcu/tree.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index c34422d..9b076b2 100644
--- 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. */
 
--
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