linux-kernel - Re: [PATCH] misc: kgdbts: Fix restrict error

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Date:   Tue, 11 Sep 2018 10:19:40 +0100
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Laura Abbott <labbott@...hat.com>
Cc:     Jason Wessel <jason.wessel@...driver.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        kgdb-bugreport@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] misc: kgdbts: Fix restrict error

On Mon, Sep 10, 2018 at 04:04:56PM -0700, Laura Abbott wrote:
> kgdbts current fails when compiled with restrict:
> 
> drivers/misc/kgdbts.c: In function ‘configure_kgdbts’:
> drivers/misc/kgdbts.c:1070:2: error: ‘strcpy’ source argument is the same as destination [-Werror=restrict]
>   strcpy(config, opt);
>   ^~~~~~~~~~~~~~~~~~~
> 
> As the error says, config is being used in both the source and destination.
> Refactor the code to only do the copy when needed.
> 
> Signed-off-by: Laura Abbott <labbott@...hat.com>
> ---
>  drivers/misc/kgdbts.c | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/misc/kgdbts.c b/drivers/misc/kgdbts.c
> index 6193270e7b3d..4447ad68ea39 100644
> --- a/drivers/misc/kgdbts.c
> +++ b/drivers/misc/kgdbts.c
> @@ -1061,20 +1061,23 @@ static void kgdbts_run_tests(void)
>  	configured = 0;
>  }
>  
> -static int kgdbts_option_setup(char *opt)
> +static void kgdbts_set_verbose(void)
>  {
> -	if (strlen(opt) >= MAX_CONFIG_LEN) {
> -		printk(KERN_ERR "kgdbts: config string too long\n");
> -		return -ENOSPC;
> -	}
> -	strcpy(config, opt);
> -
>  	verbose = 0;
>  	if (strstr(config, "V1"))
>  		verbose = 1;
>  	if (strstr(config, "V2"))
>  		verbose = 2;
> +}
>  
> +static int kgdbts_option_setup(char *opt)
> +{
> +	if (strlen(opt) >= MAX_CONFIG_LEN) {
> +		printk(KERN_ERR "kgdbts: config string too long\n");
> +		return -ENOSPC;
> +	}
> +	strcpy(config, opt);
> +	kgdbts_set_verbose();

I know this is honouring the existing code paths but I think
kgdbts_set_verbose() is redundant here. Directly setting up verbose from
kgdbts_run_tests() where the rest of the config string is parsed should
be sufficient.

Having said that I don't want to bounce perfectly correct fixes just
because they could have done more. Do you want to send a v2 or prefer me
to put further clean up on my TODO list?


Daniel.

>  	return 0;
>  }
>  
> @@ -1086,9 +1089,7 @@ static int configure_kgdbts(void)
>  
>  	if (!strlen(config) || isspace(config[0]))
>  		goto noconfig;
> -	err = kgdbts_option_setup(config);
> -	if (err)
> -		goto noconfig;
> +	kgdbts_set_verbose();
>  
>  	final_ack = 0;
>  	run_plant_and_detach_test(1);
> -- 
> 2.17.1
>