linux-kernel - Re: [PATCH v2] usb: gadget: Drop unnecessary NULL checks after container

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <YITdHl3vb5qiCHPC@pendragon.ideasonboard.com>
Date:   Sun, 25 Apr 2021 06:08:14 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v2] usb: gadget: Drop unnecessary NULL checks after
 container_of

Hi Guenter,

Thank you for the patch.

On Sat, Apr 24, 2021 at 07:54:43AM -0700, Guenter Roeck wrote:
> The parameters passed to allow_link and drop_link functions are never NULL.
> That means the result of container_of() on those parameters is also
> never NULL, even though the reference into the structure points to the
> first element of the structure. Remove the unnecessary NULL checks.
> 
> This change was made automatically with the following Coccinelle script.
> A now obsolete 'out:' label was removed manually.
> 
> @@
> type t;
> identifier v;
> statement s;
> @@
> 
> <+...
> (
>   t v = container_of(...);
> |
>   v = container_of(...);
> )
>   ...
>   when != v
> - if (\( !v \| v == NULL \) ) s
> ...+>
> 
> Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Cc: Felipe Balbi <balbi@...nel.org>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Acked-by: Felipe Balbi <balbi@...nel.org>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> ---
> v2: Dropped RFC, added Acked-by:, dropped now obsolete 'out:' label
> 
>  drivers/usb/gadget/function/uvc_configfs.c | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/drivers/usb/gadget/function/uvc_configfs.c b/drivers/usb/gadget/function/uvc_configfs.c
> index 00fb58e50a15..7775f9902360 100644
> --- a/drivers/usb/gadget/function/uvc_configfs.c
> +++ b/drivers/usb/gadget/function/uvc_configfs.c
> @@ -914,8 +914,6 @@ static int uvcg_streaming_header_allow_link(struct config_item *src,
>  
>  	target_fmt = container_of(to_config_group(target), struct uvcg_format,
>  				  group);
> -	if (!target_fmt)
> -		goto out;
>  
>  	uvcg_format_set_indices(to_config_group(target));
>  
> @@ -955,8 +953,6 @@ static void uvcg_streaming_header_drop_link(struct config_item *src,
>  	mutex_lock(&opts->lock);
>  	target_fmt = container_of(to_config_group(target), struct uvcg_format,
>  				  group);
> -	if (!target_fmt)
> -		goto out;
>  
>  	list_for_each_entry_safe(format_ptr, tmp, &src_hdr->formats, entry)
>  		if (format_ptr->fmt == target_fmt) {
> @@ -968,7 +964,6 @@ static void uvcg_streaming_header_drop_link(struct config_item *src,
>  
>  	--target_fmt->linked;
>  
> -out:
>  	mutex_unlock(&opts->lock);
>  	mutex_unlock(su_mutex);
>  }

-- 
Regards,

Laurent Pinchart