linux-kernel - Re: [PATCH] usb: mtu3: cleanup with list_first_entry_or

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Date:   Sat, 20 May 2017 21:19:40 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     linux-usb@...r.kernel.org,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: mtu3: cleanup with list_first_entry_or_null()

On Sun, May 21, 2017 at 02:05:31AM +0900, Masahiro Yamada wrote:
> The combo of list_empty() and list_first_entry() can be replaced with
> list_first_entry_or_null().
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> ---
> 
>  drivers/usb/mtu3/mtu3.h | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/usb/mtu3/mtu3.h b/drivers/usb/mtu3/mtu3.h
> index aa6fd6a..7b6dc23 100644
> --- a/drivers/usb/mtu3/mtu3.h
> +++ b/drivers/usb/mtu3/mtu3.h
> @@ -356,12 +356,8 @@ static inline struct mtu3_ep *to_mtu3_ep(struct usb_ep *ep)
>  
>  static inline struct mtu3_request *next_request(struct mtu3_ep *mep)
>  {
> -	struct list_head *queue = &mep->req_list;
> -
> -	if (list_empty(queue))
> -		return NULL;
> -
> -	return list_first_entry(queue, struct mtu3_request, list);
> +	return list_first_entry_or_null(&mep->req_list, struct mtu3_request,
> +					list);

Even better, why is this an inlined function at all?  Why not just have
it "open coded" everywhere it is used?

thanks,

greg k-h