linux-kernel - Re: [PATCH] drivers/staging/gasket: Use refcount

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Date:   Sat, 7 Jul 2018 09:22:24 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Todd Poynor <toddpoynor@...il.com>
Cc:     Rob Springer <rspringer@...gle.com>,
        John Joseph <jnjoseph@...gle.com>,
        Ben Chan <benchan@...omium.org>, devel@...verdev.osuosl.org,
        Todd Poynor <toddpoynor@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers/staging/gasket: Use refcount_read()

On Fri, Jul 06, 2018 at 11:43:10PM -0700, Todd Poynor wrote:
> From: Todd Poynor <toddpoynor@...gle.com>
> 
> Use the refcount_read accessor function, avoid reaching into refcount
> and atomic struct fields.
> 
> Signed-off-by: Todd Poynor <toddpoynor@...gle.com>
> ---
>  drivers/staging/gasket/gasket_sysfs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/gasket/gasket_sysfs.c b/drivers/staging/gasket/gasket_sysfs.c
> index d45098c90b4b..b5cdc180772a 100644
> --- a/drivers/staging/gasket/gasket_sysfs.c
> +++ b/drivers/staging/gasket/gasket_sysfs.c
> @@ -122,7 +122,7 @@ static void put_mapping(struct gasket_sysfs_mapping *mapping)
>  	}
>  
>  	mutex_lock(&mapping->mutex);
> -	if (mapping->refcount.refcount.refs.counter == 0)
> +	if (refcount_read(&mapping->refcount.refcount) == 0)
>  		gasket_nodev_error("Refcount is already 0!");
>  	if (kref_put(&mapping->refcount, release_entry)) {
>  		gasket_nodev_info("Removing Gasket sysfs mapping, device %s",

Thanks for the patch, but ugh, why in the world is this driver even
doing this type of thing?  Odds are all of these reference counting
checks can be removed, something else to add to the "todo" file...

thanks,

greg k-h