linux-kernel - Re: [PATCH] isa: Remove unnecessary checks

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Date:   Thu, 18 May 2023 21:46:21 -0400
From:   William Breathitt Gray <william.gray@...aro.org>
To:     Vladislav Efanov <VEfanov@...ras.ru>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Rene Herman <rene.herman@...access.nl>,
        linux-kernel@...r.kernel.org, lvc-project@...uxtesting.org
Subject: Re: [PATCH] isa: Remove unnecessary checks

On Wed, May 17, 2023 at 03:50:25PM +0300, Vladislav Efanov wrote:
> The isa_dev->dev.platform_data is initialized with incoming
> parameter isa_driver. After it isa_dev->dev.platform_data is
> checked for NULL, but incoming parameter isa_driver is not
> NULL since it is dereferenced many times before this check.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: a5117ba7da37 ("[PATCH] Driver model: add ISA bus")
> Signed-off-by: Vladislav Efanov <VEfanov@...ras.ru>

I don't think the Fixes line is needed because this is removing a
superfluous check rather than fixing a bug. Regardless, here's my Ack
for Greg as the patch itself makes sense.

Acked-by: William Breathitt Gray <william.gray@...aro.org>

> ---
>  drivers/base/isa.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/base/isa.c b/drivers/base/isa.c
> index 55e3ee2da98f..675ad3139224 100644
> --- a/drivers/base/isa.c
> +++ b/drivers/base/isa.c
> @@ -149,11 +149,8 @@ int isa_register_driver(struct isa_driver *isa_driver, unsigned int ndev)
>  			break;
>  		}
>  
> -		if (isa_dev->dev.platform_data) {
> -			isa_dev->next = isa_driver->devices;
> -			isa_driver->devices = &isa_dev->dev;
> -		} else
> -			device_unregister(&isa_dev->dev);
> +		isa_dev->next = isa_driver->devices;
> +		isa_driver->devices = &isa_dev->dev;
>  	}
>  
>  	if (!error && !isa_driver->devices)
> -- 
> 2.34.1
> 

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