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

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Date:   Sat, 24 Apr 2021 08:01:28 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Felipe Balbi <balbi@...nel.org>
Subject: Re: [RFC PATCH] usb: gadget: Drop unnecessary NULL checks after
 container_of

On Fri, Apr 23, 2021 at 08:06:26AM -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 if the reference into the structure points to the first
> element of the structure. Remove the subsequent NULL checks.
> 
> The changes in this patch were made automatically using the following
> Coccinelle script.
> 
> @@
> 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>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
> After the recent discussion about a patch which tried to add a check
> against NULL after container_of(), I realized that there are a number
> of such checks in the kernel.
> 
> Now the big question: Are patches like this acceptable, or do they count
> as noise ?

Yes they are acceptable, and no, they are not noise.

I will be glad to take this after -rc1 is out, thanks.

thanks,

greg k-h