linux-kernel - Re: [BUG] checkpatch: false positive storage class location

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Message-ID: <1499256099.19466.5.camel@perches.com>
Date:   Wed, 05 Jul 2017 05:01:39 -0700
From:   Joe Perches <joe@...ches.com>
To:     Heinrich Schuchardt <xypron.glpk@....de>,
        Andy Whitcroft <apw@...onical.com>
Cc:     linux-kernel@...r.kernel.org, u-boot@...ts.denx.de
Subject: Re: [BUG] checkpatch: false positive storage class location

On Tue, 2017-07-04 at 23:08 +0200, Heinrich Schuchardt wrote:
> On 07/04/2017 10:44 PM, Joe Perches wrote:
> > On Tue, 2017-07-04 at 21:29 +0200, Heinrich Schuchardt wrote:
> > > The U-Boot project uses the same scripts/checkpatch.pl as the Linux
> > > kernel. I ran upon the problem below when working on U-Boot. But I
> > > guess it should be fixed in the Linux upstream.
> > > 
> > > Running checkpatch for this email produces
> > > WARNING: storage class should be at the beginning of the declaration
> > > 
> > > This relates to the parameter with asmlinkage.
> > > 
> > > asmlinkage is at the start of the parameter so I think this a false
> > > positive.
> > > 
> > > Signed-off-by: Heinrich.Schuchardt <xypron.glpk@....de>
> > > ---
> > > 
> > >  cmd/bootefi.c | 22 +++++++++++++++++-----
> > >  1 file changed, 17 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/cmd/bootefi.c b/cmd/bootefi.c
> > > index 771300ee94..4df468307c 100644
> > > --- a/cmd/bootefi.c
> > > +++ b/cmd/bootefi.c
> > > @@ -147,6 +147,12 @@ static void *copy_fdt(void *fdt)
> > >  	return new_fdt;
> > >  }
> > >  
> > > +static ulong efi_do_enter(void *image_handle,
> > > +		struct efi_system_table *st, asmlinkage ulong (*entry)(
> > > +		void *image_handle, struct efi_system_table *st))
> > > +{
> > > +	return 0;
> > > +}
> > > +
> > >  /*
> > >  end
> > >  */
> > 
> > Perhaps this?
> > -------------------------
> > 
> > Allow storage class after comma for function pointers.
> > 
> > Miscellanea:
> > 
> > o Add missing semicolon after WARN statement
> > ---
> >  scripts/checkpatch.pl | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> > index 43171ed88115..c7490ab48ce1 100755
> > --- a/scripts/checkpatch.pl
> > +++ b/scripts/checkpatch.pl
> > @@ -5577,9 +5577,10 @@ sub process {
> >  		}
> >  
> >  # Check that the storage class is at the beginning of a declaration
> > -		if ($line =~ /\b$Storage\b/ && $line !~ /^.\s*$Storage\b/) {
> > +		if ($line =~ /\b$Storage\b/ &&
> > +		    $line !~ /^.\s*(?:.*,\s*)?$Storage\b/) {
> >  			WARN("STORAGE_CLASS",
> > -			     "storage class should be at the beginning of the declaration\n" . $herecurr)
> > +			     "storage class should be at the beginning of the declaration\n" . $herecurr);
> >  		}
> >  
> >  # check the location of the inline attribute, that it is between
> > 
> 
> Thank you. This works for all cases but
> 
> +static ulong efi_do_enter(ulong asmlinkage (*entry)(void *image_handle,
> +                          struct efi_system_table *st))
> +{
> +       return 0;
> +}
> +
> 
> Here I get
> WARNING: space prohibited between function name and open parenthesis '('
> where I would have expected
> WARNING: storage class should be at the beginning of the declaration

checkpatch is and always will be a stupid brainless
little script based on a collection of regexes.

It won't get everything correct.

Your example has static as the first entry on the line.
static is a "$Storage" so it is at the beginning of the
declaration.

This particular declaration has a function pointer
as one of its arguments.

I do wonder if asmlinkage is even appropriate as part of
that function pointer argument.

Anyway, maybe this:
---
 scripts/checkpatch.pl | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 43171ed88115..21bb6814f8bb 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5576,10 +5576,18 @@ sub process {
 			    "architecture specific defines should be avoided\n" .  $herecurr);
 		}
 
+# check that the storage class is not after a type
+		if ($line =~ /\b($Type)\s+($Storage)\b/) {
+			WARN("STORAGE_CLASS",
+			     "storage class '$2' should be located before type '$1'\n" . $herecurr);
+		}
 # Check that the storage class is at the beginning of a declaration
-		if ($line =~ /\b$Storage\b/ && $line !~ /^.\s*$Storage\b/) {
+		if ($line =~ /\b$Storage\b/ &&
+		    $line !~ /^.\s*$Storage/ &&
+		    $line =~ /^.\s*(.+?)\$Storage\s/ &&
+		    $1 !~ /[\,\)]\s*$/) {
 			WARN("STORAGE_CLASS",
-			     "storage class should be at the beginning of the declaration\n" . $herecurr)
+			     "storage class should be at the beginning of the declaration\n" . $herecurr);
 		}
 
 # check the location of the inline attribute, that it is between