Message-ID: <1449884094.3564.6.camel@perches.com>
Subject: Re: [BUG] checkpatch warning default switch case
From: Joe Perches <joe@perches.com>
To: "Geyslan G. Bem" <geyslan@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Andy Whitcroft <apw@canonical.com>,
        Peter Senna Tschudin <peter.senna@gmail.com>
Date: Fri, 11 Dec 2015 17:34:54 -0800
In-Reply-To: <CAGG-pUTh6stPf+DuEjEkMTQSMoOSZ1a02KbpFef8CFG5_5AHHQ@mail.gmail.com>
References: <CAGG-pUR5GgrbgurcrTwGCpPMdMyJBvn_JSah77wVG2t7TBEpBw@mail.gmail.com>
	 <1449864511.3564.4.camel@perches.com>
	 <CAGG-pUQtKV7cCO_NXqj=+K=9BehzaFru3Dmei7onz+XNnV3YPw@mail.gmail.com>
	 <CAGG-pUTh6stPf+DuEjEkMTQSMoOSZ1a02KbpFef8CFG5_5AHHQ@mail.gmail.com>
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On Fri, 2015-12-11 at 18:56 -0300, Geyslan G. Bem wrote:
> 2015-12-11 17:21 GMT-03:00 Geyslan G. Bem <geyslan@gmail.com>:
> > 2015-12-11 17:08 GMT-03:00 Joe Perches <joe@perches.com>:
> > > On Fri, 2015-12-11 at 16:34 -0300, Geyslan G. Bem wrote:
> > > > Hello,
> > > > 
> > > > Running
> > > > scripts/checkpatch.pl -f drivers/usb/host/ehci-sched.c
> > > > 
> > > > I got this
> > > > ...
> > > > ERROR: spaces required around that ':' (ctx:VxE)
> > > > #496: FILE: drivers/usb/host/ehci-sched.c:496:
> > > > +???????????????????????default:
> > > > ...
> > > > 
> > > > 
> > > > 496:????????????default:
> > > > ????????????????????????ehci_dbg (ehci,
> > > > ????????????????????????????????"periodic frame %d bogus type
> > > > %d\n",
> > > > ????????????????????????????????frame, type);
> > > > ????????????????}
> > > > 
> > > > It seems a correct use of default switch case. Maybe the test
> > > > concerns
> > > > to ternary conditional.
> > > > 
> > > > Let me know.
> > > 
> > > Yes, it's a checkpatch defect.
> > > 
> > > It's because a c99 style comment is immediately before this line.
> > > 
> > > ????????switch (foo) {
> > > ????????case 1:
> > > ????????????????break;
> > > ????????// foo
> > > ????????default:
> > > ????????????????break;
> > > ????????}
> > > 
> > > emits this ERROR
> > > 
> > > I suggest you fix the comment and the message will go away.
> > Ok, I'm fixing it.
> > 
> > Tks.
> > > 
> > > Andy???Do you care to fix this defect?
> > > 
> > 
> 
> Another false positive:
> 
> WARNING: braces {} are not necessary for single statement blocks
> #1570: FILE: drivers/usb/host/ehci-sched.c:1570:
> +???????????????else {
> +???????????????????????start = (stream->ps.phase << 3) +
> stream->ps.phase_uf;
> +???????????????}
> 
> The code:
> 
> ????????if (stream->ps.phase == NO_FRAME) {
> ????????????int????????done = 0;
> ...
> ????????????reserve_release_iso_bandwidth(ehci, stream, 1);
> ????????}
> 
> ????????/* New stream is already scheduled; use the upcoming slot */
> ????????else {
> ????????????start = (stream->ps.phase << 3) + stream->ps.phase_uf;
> ????????}
> 
> There's a C89 comment before the else branch and immediately before
> that an empty line. They, I think, are confusing the parser.

checkpatch isn't a real parser

Move the comment into the else block

	if (...) {
		...;
	} else {
		/* New stream ... */
		start = ...;
	}


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