linux-kernel - Re: [PATCH v2] checkpatch: Add a warning for log messages that don't end in a new line

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Date:   Mon, 27 Nov 2017 09:26:05 -0800
From:   Joe Perches <joe@...ches.com>
To:     Logan Gunthorpe <logang@...tatee.com>,
        Julia Lawall <julia.lawall@...6.fr>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Andy Whitcroft <apw@...onical.com>
Subject: Re: [PATCH v2] checkpatch: Add a warning for log messages that
 don't end in a new line

On Mon, 2017-11-27 at 10:07 -0700, Logan Gunthorpe wrote:
> 
> On 27/11/17 02:25 AM, Joe Perches wrote:
> > []
> > diff -u -p a/lib/locking-selftest.c b/lib/locking-selftest.c
> > --- a/lib/locking-selftest.c
> > +++ b/lib/locking-selftest.c
> > @@ -1186,7 +1186,7 @@ static void dotest(void (*testcase_fn)(v
> > 
> >   static inline void print_testname(const char *testname)
> >   {
> > -	printk("%33s:", testname);
> > +	printk("%33s:\n", testname);
> >   }
> 
> Coincidentally, the checkpatch script does not hit this false positive. 
> This because a pr_cont actually follows in a #define. It doesn't feel 
> right but checkpatch does do the correct thing on this one.
> 
> > diff -u -p a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> > --- a/lib/dynamic_debug.c
> > +++ b/lib/dynamic_debug.c
> > @@ -562,7 +562,8 @@ void __dynamic_pr_debug(struct _ddebug *
> >   	vaf.fmt = fmt;
> >   	vaf.va = &args;
> > 
> > -	printk(KERN_DEBUG "%s%pV", dynamic_emit_prefix(descriptor, buf), &vaf);
> > +	printk(KERN_DEBUG "%s%pV\n", dynamic_emit_prefix(descriptor, buf),
> > +	       &vaf);
> > 
> >   	va_end(args);
> >   }
> 
> This is a valid false positive that I also missed. However, it can 
> actually be very easily ignored by checking if the format string ends in 
> %pV. There were about 100 cases in my results that match this.

No, it can't be done that way.

$ git grep '%pV\\n"' | wc -l
56
$ git grep '%pV"' | wc -l
146

AFAIK: all of the above are correct as-is.