linux-kernel - Re: linux-next: Tree for Feb 8 (objtool: warnings: 5)

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Message-ID: <14d25a4e-8163-b29f-0297-47dcda59cb77@infradead.org>
Date:   Tue, 9 Feb 2021 16:16:11 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: linux-next: Tree for Feb 8 (objtool: warnings: 5)

On 2/9/21 2:59 PM, Josh Poimboeuf wrote:
> On Mon, Feb 08, 2021 at 01:39:03PM -0800, Randy Dunlap wrote:
>> On 2/8/21 1:21 PM, Josh Poimboeuf wrote:
>>> On Mon, Feb 08, 2021 at 11:30:59AM -0800, Randy Dunlap wrote:
>>>> On 2/8/21 4:52 AM, Stephen Rothwell wrote:
>>>>> Hi all,
>>>>>
>>>>> Changes since 20210205:
>>>>>
>>>>
>>>> on x86_64:
>>>>
>>>> objtool warnings: (from 3 different randconfig builds)
>>>>
>>>> drivers/input/touchscreen/elants_i2c.o: warning: objtool: elants_i2c_initialize() falls through to next function elants_i2c_resume()
>>>
>>> Randy, can you share the .o?  (you may need to gzip it, still waiting on
>>> corporate IT to allow me to receive .o files)
>>
>> Sure, no problem. It's attached.
> 
> Does this fix?
> 
> From: Josh Poimboeuf <jpoimboe@...hat.com>
> Subject: [PATCH] input/elants_i2c: Detect enum overflow
> 
> If an enum value were to get added without updating this switch
> statement, the unreachable() annotation would trigger undefined
> behavior, causing execution to fall through the end of the function,
> into the next one.
> 
> Make the error handling more robust for an unexpected enum value, by
> doing BUG() instead of unreachable().
> 
> Fixes the following objtool warning:
> 
>   drivers/input/touchscreen/elants_i2c.o: warning: objtool: elants_i2c_initialize() falls through to next function elants_i2c_resume()
> 
> Reported-by: Randy Dunlap <rdunlap@...radead.org>
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>

Yes, thanks.

Acked-by: Randy Dunlap <rdunlap@...radead.org>

> ---
>  drivers/input/touchscreen/elants_i2c.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c
> index 6f57ec579f00..4c2b579f6c8b 100644
> --- a/drivers/input/touchscreen/elants_i2c.c
> +++ b/drivers/input/touchscreen/elants_i2c.c
> @@ -656,8 +656,7 @@ static int elants_i2c_initialize(struct elants_data *ts)
>  			error = elants_i2c_query_ts_info_ektf(ts);
>  		break;
>  	default:
> -		unreachable();
> -		break;
> +		BUG();
>  	}
>  
>  	if (error)
> 


-- 
~Randy