linux-kernel - Re: [PATCH] mm: Use fallthrough;

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Message-ID: <84f3c9891d4e89909d5537f34ea9d75de339c415.camel@perches.com>
Date:   Sun, 08 Mar 2020 21:51:07 -0700
From:   Joe Perches <joe@...ches.com>
To:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Hugh Dickins <hughd@...gle.com>,
        Minchan Kim <minchan@...nel.org>,
        Nitin Gupta <ngupta@...are.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        cgroups@...r.kernel.org
Subject: Re: [PATCH] mm: Use fallthrough;

On Mon, 2020-03-09 at 13:15 +0900, Sergey Senozhatsky wrote:
> On (20/03/07 19:54), Joe Perches wrote:
> > On Sun, 2020-03-08 at 12:18 +0900, Sergey Senozhatsky wrote:
> > > On (20/03/06 23:58), Joe Perches wrote:
> > > [..]
> > > > --- a/mm/mempolicy.c
> > > > +++ b/mm/mempolicy.c
> > > > @@ -907,7 +907,6 @@ static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
> > > >  
> > > >  	switch (p->mode) {
> > > >  	case MPOL_BIND:
> > > > -		/* Fall through */
> > > >  	case MPOL_INTERLEAVE:
> > 
> > Consecutive case labels do not need an interleaving fallthrough;
> > 
> > ie: ditto
> 
> I see. Shall this be mentioned in the commit message, maybe?

<shrug, maybe>  I've no real opinion about that necessity.

fallthrough commments are relatively rarely used as a
separating element between case labels.

It's by far most common to just have consecutive case labels
without any other content.

It's somewhere between 500:1 to 1000:1 in the kernel.