From: Chen Gang <gang.chen@asianux•com>
To: David Miller <davem@davemloft•net>
Cc: Christophe Aeschlimann <c.aeschlimann@acn-group•ch>,
sergei.shtylyov@cogentembedded•com,
alex.bluesman.smirnov@gmail•com, dbaryshkov@gmail•com,
linux-zigbee-devel@lists•sourceforge.net, netdev@vger•kernel.org
Subject: Re: [PATCH v4] net: mac802154: comparision issue of type cast, finding by EXTRA_CFLAGS=-W
Date: Thu, 25 Apr 2013 17:40:29 +0800 [thread overview]
Message-ID: <5178FA0D.8060009@asianux.com> (raw)
In-Reply-To: <5178F120.5030500@acn-group.ch>
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@asianux•com>
---
net/mac802154/mac802154.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/mac802154/mac802154.h b/net/mac802154/mac802154.h
index a4dcaf1..703c121 100644
--- a/net/mac802154/mac802154.h
+++ b/net/mac802154/mac802154.h
@@ -90,7 +90,7 @@ struct mac802154_sub_if_data {
#define MAC802154_MAX_XMIT_ATTEMPTS 3
-#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;
--
1.7.11.7
next prev parent reply other threads:[~2013-04-25 9:41 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-22 6:41 [PATCH] Net: mac802154: comparing issue by type cast, finding by EXTRA_CFLAGS=-W Chen Gang
2013-04-22 14:09 ` Sergei Shtylyov
2013-04-23 1:11 ` Chen Gang
2013-04-23 2:54 ` [PATCH v2] Net: mac802154: comparision issue of " Chen Gang
2013-04-23 11:22 ` Chen Gang
2013-04-23 11:24 ` [PATCH v3] net: " Chen Gang
2013-04-25 8:10 ` David Miller
2013-04-25 8:43 ` Chen Gang
2013-04-25 9:01 ` David Miller
2013-04-25 9:09 ` Chen Gang
[not found] ` <5178ECA2.6020402-bOixZGp5f+dBDgjK7y7TUQ@public.gmane.org>
2013-04-25 9:02 ` Christophe Aeschlimann
2013-04-25 9:06 ` Chen Gang
2013-04-25 9:40 ` Chen Gang [this message]
2013-04-25 9:59 ` [PATCH v4] " Daniel Borkmann
2013-04-25 10:44 ` Chen Gang
2013-04-25 10:49 ` [PATCH v5] " Chen Gang
2013-04-29 16:29 ` David Miller
2013-05-02 1:11 ` Chen Gang
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