Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754566AbbLJR01 (ORCPT ); Thu, 10 Dec 2015 12:26:27 -0500 Received: from mail-lb0-f175.google.com ([209.85.217.175]:35198 "EHLO mail-lb0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754493AbbLJR0X (ORCPT ); Thu, 10 Dec 2015 12:26:23 -0500 Subject: Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros To: "Geyslan G. Bem" References: <1449700359-14262-1-git-send-email-geyslan@gmail.com> <1449700359-14262-4-git-send-email-geyslan@gmail.com> <5669680E.4070304@cogentembedded.com> <56698FB3.9030705@cogentembedded.com> Cc: Peter Senna Tschudin , Alan Stern , Greg Kroah-Hartman , linux-usb@vger.kernel.org, LKML From: Sergei Shtylyov Organization: Cogent Embedded Message-ID: <5669B5BB.6060608@cogentembedded.com> Date: Thu, 10 Dec 2015 20:26:19 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2068 Lines: 68 On 12/10/2015 05:56 PM, Geyslan G. Bem wrote: >>>>>> Don't use the 'do {} while (0)' wrapper in a single statement macro. >>>>>> >>>>>> Caught by checkpatch: "WARNING: Single statement macros should not >>>>>> use a do {} while (0) loop" >>>>>> >>>>>> Signed-off-by: Geyslan G. Bem >>>>>> --- >>>>>> drivers/usb/host/ehci.h | 4 ++-- >>>>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>>>> >>>>>> diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h >>>>>> index cfeebd8..945000a 100644 >>>>>> --- a/drivers/usb/host/ehci.h >>>>>> +++ b/drivers/usb/host/ehci.h >>>>>> @@ -244,9 +244,9 @@ struct ehci_hcd { /* one per >>>>>> controller */ >>>>>> /* irq statistics */ >>>>>> #ifdef EHCI_STATS >>>>>> struct ehci_stats stats; >>>>>> -# define COUNT(x) do { (x)++; } while (0) >>>>>> +# define COUNT(x) ((x)++) >>>>>> #else >>>>>> -# define COUNT(x) do {} while (0) >>>>>> +# define COUNT(x) ((void) 0) >>>>> >>>>> >>>>> >>>>> Why not just empty #define? >>>> >>>> >>>> Indeed. I'll change it. >>>> Tks Sergei. >>> >>> >>> Since COUNT is not used to return the empty #define is ok. Another way >>> is to use #define COUNT(x) (0) to get a 0 when necessary to read >>> returns. >> Just 0, no parens please. > Ok, no parens, since there's no evaluation. It's because the literals don't need parens at all. > Then my change is: > > -# define COUNT(x) do { (x)++; } while (0) > +# define COUNT(x) (++(x)) > #else > -# define COUNT(x) do {} while (0) > +# define COUNT(x) 0 > > Pre-increment allowing to return the updated x. Why if there was a post-increment before? Anyway, this talk is quite pointless since the macro didn't return any value anyway. MBR, Sergei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/