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Message-ID: <51766F74.2090007@asianux.com>
Date: Tue, 23 Apr 2013 19:24:36 +0800
From: Chen Gang <gang.chen@...anux.com>
To: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
CC: alex.bluesman.smirnov@...il.com, dbaryshkov@...il.com,
David Miller <davem@...emloft.net>,
linux-zigbee-devel@...ts.sourceforge.net,
netdev <netdev@...r.kernel.org>
Subject: [PATCH v3] net: mac802154: comparision issue of type cast, finding
by EXTRA_CFLAGS=-W
Need change ~(u8)0 to 0xff, or in mac802154_wpan_xmit(), "u8 chan"
will never == MAC802154_CHAN_NONE.
The related warning:
net/mac802154/wpan.c:325:2: warning: comparison is always false
due to limited range of data type [-Wtype-limits]
The related unit test:
cc -Wall -O2 -o test test.c
./test
will output 'different'
(after use '0xff' instead of '~(u8)0', it will output 'equal')
-----------------------test code begin--------------------------------
#include <stdio.h>
typedef unsigned char u8;
int main()
{
u8 uc = 0xff;
if (uc == ~(u8)0)
printf("\nequal\n");
else
printf("\ndifferent\n");
return 0;
}
-----------------------test code end----------------------------------
Signed-off-by: Chen Gang <gang.chen@...anux.com>
---
net/mac802154/mac802154.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/net/mac802154/mac802154.h b/net/mac802154/mac802154.h
index 5c9e021..d48422e 100644
--- a/net/mac802154/mac802154.h
+++ b/net/mac802154/mac802154.h
@@ -88,7 +88,7 @@ struct mac802154_sub_if_data {
#define mac802154_to_priv(_hw) container_of(_hw, struct mac802154_priv, hw)
-#define MAC802154_CHAN_NONE (~(u8)0) /* No channel is assigned */
+#define MAC802154_CHAN_NONE 0xff /* No channel is assigned */
extern struct ieee802154_reduced_mlme_ops mac802154_mlme_reduced;
extern struct ieee802154_mlme_ops mac802154_mlme_wpan;
--
1.7.7.6
--
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