linux-kernel - Re: [PATCH] staging: erofs: Add braces to do-while statements

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Message-ID: <f741ac1808f05f2efe6532491e8b1eb6ac74e260.camel@perches.com>
Date:   Sun, 09 Dec 2018 09:27:01 -0800
From:   Joe Perches <joe@...ches.com>
To:     Greg KH <gregkh@...uxfoundation.org>,
        Thomas Jespersen <laumann.thomas@...il.com>
Cc:     gaoxiang25@...wei.com, yuchao0@...wei.com,
        linux-erofs@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: erofs: Add braces to do-while statements

On Sun, 2018-12-09 at 17:20 +0100, Greg KH wrote:
> On Sun, Dec 09, 2018 at 04:59:00PM +0100, Thomas Jespersen wrote:
> > This fixes warning reported by sparse (with -Wsparse-all).
> 
> Why is sparse warning about this?

Probably because it's the kernel preferred style
to use single statement

	do {
		<foo>;
	} while (<bar>);

over

by about a 20:1 ratio.

> > Signed-off-by: Thomas Jespersen <laumann.thomas@...il.com>obab
> > ---
> >  drivers/staging/erofs/internal.h | 4 ++--
> >  drivers/staging/erofs/utils.c    | 4 ++--
> >  2 files changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
> > index 57575c7f5635..bf180a803446 100644
> > --- a/drivers/staging/erofs/internal.h
> > +++ b/drivers/staging/erofs/internal.h
> > @@ -232,9 +232,9 @@ static inline bool erofs_workgroup_get(struct erofs_workgroup *grp, int *ocnt)
> >  	/* spin if it is temporarily locked at the reclaim path */
> >  	if (unlikely(o == locked)) {
> >  #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
> > -		do
> > +		do {
> >  			cpu_relax();
> > -		while (atomic_read(&grp->refcount) == locked);
> > +		} while (atomic_read(&grp->refcount) == locked);
> 
> That looks like valid code to me, why change this?
> 
> greg k-h