linux-kernel - Re: [PATCH] target: pscsi: avoid Wempty-body warning

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Date:   Mon, 22 Mar 2021 17:26:01 +0100
From:   Willy Tarreau <w@....eu>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Christoph Hellwig <hch@...radead.org>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Jens Axboe <axboe@...nel.dk>,
        Chaitanya Kulkarni <chaitanya.kulkarni@....com>,
        Hannes Reinecke <hare@...e.de>,
        Bodo Stroesser <bstroesser@...fujitsu.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Guoqing Jiang <guoqing.jiang@...ud.ionos.com>,
        linux-scsi <linux-scsi@...r.kernel.org>,
        target-devel@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] target: pscsi: avoid Wempty-body warning

On Mon, Mar 22, 2021 at 05:18:23PM +0100, Arnd Bergmann wrote:
> I agree that this instance of the warning is particularly stupid, but the
> I'd like to leave the warning option there and eventually enable it by
> default because it tends to find other more interesting cases, and this
> one is trivial to work around.
> 
> I remember previously fixing a few drivers that did obviously
> incorrect things like
> 
>     if (error); /* note the extra ';' */
>          return error;

I totally agree with this one but usually it's already reported by
another one (probably the one complaining about misindenting). The
case I've seen quite a few times was:

     while (condition);

At least I want the ';' on its own line to avoid it being
confused with one that ends a do {} while() block.

> and a lot mostly harmless code like
> 
> #ifdef DEBUG_THIS_DRIVER /* always disabled */
> #define dprintk(args...) printk(args)
> #else
> #define dprintk(args...)
> #endif
>     /* note the mismatched format string */
>     dprintk(KERN_WARNING "error %d\n", &object);
> 
> Turning the empty dprintk() into no_printk() means we can catch
> the wrong format string during compile testing.

Hmmm OK for this one. With this said, given how plenty of warnings seem
to consider indent and whatever, I wouldn't be surprised if a difference
is made between a totally empty body and one that results from an empty
macro. But indeed this one can represent a real bug.

Willy