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Subject: [PATCH] checkpatch/coding-style: Allow 100 column lines
From:   Joe Perches <joe@perches.com>
To:     Linus Torvalds <torvalds@linux-foundation.org>,
        David Laight <David.Laight@aculab.com>
Cc:     Casey Schaufler <casey@schaufler-ca.com>,
        David Howells <dhowells@redhat.com>,
        Christoph Hellwig <hch@lst.de>,
        Al Viro <viro@zeniv.linux.org.uk>, Ian Kent <raven@themaw.net>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        LSM List <linux-security-module@vger.kernel.org>,
        NetFilter <netfilter-devel@vger.kernel.org>
Date:   Fri, 29 May 2020 16:12:21 -0700
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Change the maximum allowed line length to 100 from 80.

Miscellanea:

o to avoid unnecessary whitespace changes in files,
  checkpatch will no longer emit a warning about line length
  when scanning files unless --strict is also used
o Add a bit to coding-style about alignment to open parenthesis

Signed-off-by: Joe Perches <joe@perches.com>
---
 Documentation/process/coding-style.rst | 25 ++++++++++++++++---------
 scripts/checkpatch.pl                  | 14 +++++++++-----
 2 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst
index acb2f1b36350..55b148e9c6b8 100644
--- a/Documentation/process/coding-style.rst
+++ b/Documentation/process/coding-style.rst
@@ -84,15 +84,22 @@ Get a decent editor and don't leave whitespace at the end of lines.
 Coding style is all about readability and maintainability using commonly
 available tools.
 
-The limit on the length of lines is 80 columns and this is a strongly
-preferred limit.
-
-Statements longer than 80 columns will be broken into sensible chunks, unless
-exceeding 80 columns significantly increases readability and does not hide
-information. Descendants are always substantially shorter than the parent and
-are placed substantially to the right. The same applies to function headers
-with a long argument list. However, never break user-visible strings such as
-printk messages, because that breaks the ability to grep for them.
+The preferred limit on the length of a single line is 80 columns.
+
+Statements longer than 80 columns should be broken into sensible chunks,
+unless exceeding 80 columns significantly increases readability and does
+not hide information.
+
+Statements may be up to 100 columns when appropriate.
+
+Descendants are always substantially shorter than the parent and are
+are placed substantially to the right.  A very commonly used style
+is to align descendants to a function open parenthesis.
+
+These same rules are applied to function headers with a long argument list.
+
+However, never break user-visible strings such as printk messages because
+that breaks the ability to grep for them.
 
 
 3) Placing Braces and Spaces
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index dd750241958b..5f00df2c3f59 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -53,7 +53,7 @@ my %ignore_type = ();
 my @ignore = ();
 my $help = 0;
 my $configuration_file = ".checkpatch.conf";
-my $max_line_length = 80;
+my $max_line_length = 100;
 my $ignore_perl_version = 0;
 my $minimum_perl_version = 5.10.0;
 my $min_conf_desc_length = 4;
@@ -99,9 +99,11 @@ Options:
   --types TYPE(,TYPE2...)    show only these comma separated message types
   --ignore TYPE(,TYPE2...)   ignore various comma separated message types
   --show-types               show the specific message type in the output
-  --max-line-length=n        set the maximum line length, if exceeded, warn
+  --max-line-length=n        set the maximum line length, (default $max_line_length)
+                             if exceeded, warn on patches
+                             requires --strict for use with --file
   --min-conf-desc-length=n   set the min description length, if shorter, warn
-  --tab-size=n               set the number of spaces for tab (default 8)
+  --tab-size=n               set the number of spaces for tab (default $tabsize)
   --root=PATH                PATH to the kernel tree root
   --no-summary               suppress the per-file summary
   --mailback                 only produce a report in case of warnings/errors
@@ -3282,8 +3284,10 @@ sub process {
 
 			if ($msg_type ne "" &&
 			    (show_type("LONG_LINE") || show_type($msg_type))) {
-				WARN($msg_type,
-				     "line over $max_line_length characters\n" . $herecurr);
+				my $msg_level = \&WARN;
+				$msg_level = \&CHK if ($file);
+				&{$msg_level}($msg_type,
+					      "line length of $length exceeds $max_line_length columns\n" . $herecurr);
 			}
 		}