From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
To: Chen Gang <gang.chen@asianux.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] Net: mac802154: comparing issue by type cast, finding by EXTRA_CFLAGS=-W
Date: Mon, 22 Apr 2013 18:09:09 +0400 [thread overview]
Message-ID: <51754485.6040708@cogentembedded.com> (raw)
In-Reply-To: <5174DB87.3010908@asianux.com>
Hello.
On 22-04-2013 10:41, Chen Gang wrote:
> need change ~(u8)0 to 0xff,
> or in mac802154_wpan_xmit(), "u8 chan" will never == MAC802154_CHAN_NONE
> find it by "make EXTRA_CFLAGS=-W"
> 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..c59309f 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 */
() not needed now.
WBR, Sergei
next prev parent reply other threads:[~2013-04-22 14:10 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 [this message]
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 ` [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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