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

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Date:   Mon, 22 Mar 2021 17:34:48 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Willy Tarreau <w@....eu>
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 5:26 PM Willy Tarreau <w@....eu> wrote:
> On Mon, Mar 22, 2021 at 05:18:23PM +0100, Arnd Bergmann wrote:
> > 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.

The -Wempty-body warning is actually really old and predates the compiler's
understanding of indentation, we just always disabled it by default so far.

As a lot of subsystems are W=1 clean these days, I just went for the
final 26 patches to shut up all empty-body warnings in randconfig builds.
Most of these were in the dprink() category, though none of this last set
actually had incorrect format strings.

          Arnd