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Message-ID: <1536696163.3024.146.camel@codethink.co.uk>
Subject: Re: [PATCH 4.4 47/79] ieee802154: at86rf230: switch from BUG_ON()
 to WARN_ON() on problem
From:   Ben Hutchings <ben.hutchings@codethink.co.uk>
To:     Stefan Schmidt <stefan@datenfreihafen.org>,
        Sasha Levin <alexander.levin@microsoft.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        stable <stable@vger.kernel.org>
Date:   Tue, 11 Sep 2018 21:02:43 +0100
In-Reply-To: <20180823074922.172707485@linuxfoundation.org>
References: <20180823074918.641878835@linuxfoundation.org>
         <20180823074922.172707485@linuxfoundation.org>
Organization: Codethink Ltd.
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On Thu, 2018-08-23 at 09:53 +0200, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Stefan Schmidt <stefan@datenfreihafen.org>
> 
> [ Upstream commit 20f330452ad8814f2289a589baf65e21270879a7 ]
> 
> The check is valid but it does not warrant to crash the kernel. A
> WARN_ON() is good enough here.
> Found by checkpatch.

If the BUG/WARN fires, the very next statement is going to cause an
oops.  So this doesn't fix anything.

Either it's OK for a null pointer to be a fatal error, in which case
the WARN can be removed, or that shouldn't be a fatal error, in which
case the following assignment needs to be conditional.

Ben.

> Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/net/ieee802154/at86rf230.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- a/drivers/net/ieee802154/at86rf230.c
> +++ b/drivers/net/ieee802154/at86rf230.c
> @@ -932,7 +932,7 @@ at86rf230_xmit(struct ieee802154_hw *hw,
>  static int
>  at86rf230_ed(struct ieee802154_hw *hw, u8 *level)
>  {
> -	BUG_ON(!level);
> +	WARN_ON(!level);
>  	*level = 0xbe;
>  	return 0;
>  }

-- 
Ben Hutchings, Software Developer                         Codethink Ltd
https://www.codethink.co.uk/                 Dale House, 35 Dale Street
                                     Manchester, M1 2HF, United Kingdom