From: Chen Gang <gang.chen@asianux.com>
To: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: alex.bluesman.smirnov@gmail.com, dbaryshkov@gmail.com,
David Miller <davem@davemloft.net>,
linux-zigbee-devel@lists.sourceforge.net,
netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH v2] Net: mac802154: comparision issue of type cast, finding by EXTRA_CFLAGS=-W
Date: Tue, 23 Apr 2013 19:22:57 +0800 [thread overview]
Message-ID: <51766F11.6080201@asianux.com> (raw)
In-Reply-To: <5175F7F7.7000703@asianux.com>
I will send patch v3 for properly capitalizing my comments' sentences
and subject.
On 2013年04月23日 10:54, Chen Gang wrote:
>
> 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]
>
> 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 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;
>
--
Chen Gang
Asianux Corporation
next prev parent reply other threads:[~2013-04-23 11:23 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 [this message]
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 ` [PATCH v4] " Chen Gang
2013-04-25 9:59 ` 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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