linux-kernel - [PATCH] lib/idr.c: remove duplicate bound checking in sub

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Date:	Fri, 20 Mar 2015 11:45:27 +0000
From:	Liu Sha <sz_liusha@...ctratech.com>
To:	<akpm@...ux-foundation.org>
CC:	<linux-kernel@...r.kernel.org>, <rednoax@...il.com>
Subject: [PATCH] lib/idr.c: remove duplicate bound checking in sub_alloc

The INT_MAX bound checking in sub_alloc checks two conditions to see
whether the signed integer "id" is beyond INT_MAX:

		if ((id >= MAX_IDR_BIT) || (id < 0))
			return -ENOSPC;

These two conditions are actually the same for "int" variable so one
of them can be removed. If the above snippet is compiled with -Os option
of gcc, only "id < 0" will remain in disassembly code.

Signed-off-by: Liu Sha <sz_liusha@...ctratech.com>
---
 lib/idr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/idr.c b/lib/idr.c
index 5335c43..df545ad 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -262,7 +262,7 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa,
 			sh = IDR_BITS*l;
 			id = ((id >> sh) ^ n ^ m) << sh;
 		}
-		if ((id >= MAX_IDR_BIT) || (id < 0))
+		if (id >= MAX_IDR_BIT)
 			return -ENOSPC;
 		if (l == 0)
 			break;
-- 
2.1.1

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