[PATCH] checkpatch: fix false positive for COMMIT_LOG_LONG_LINE with URLs

[Aditya Srivastava <yashsri421@gmail.com>]

Currently checkpatch warns for long line in commit messages even for
URL lines.

An evaluation over v4.13..v5.8 showed that out of ~11000 warnings for
this class, around 790 are due to the line containing link.

E.g. running checkpatch on commit 3cde818cd02b ("ASoC: topology:
Consolidate how dtexts and dvalues are freed") reports this warning:

WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
https://mailman.alsa-project.org/pipermail/alsa-devel/2019-January/144761.html

Avoid giving users warning for character limit, instead suggest them to
prefix the URLs with "Link:"

Signed-off-by: Aditya Srivastava <yashsri421@gmail.com>
---
 scripts/checkpatch.pl | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index abd5a3d2e913..23da1f50fe6a 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3032,8 +3032,14 @@ sub process {
 		      $line =~ /^\s*(?:Fixes:|Link:|$signature_tags)/i ||
 					# A Fixes: or Link: line or signature tag line
 		      $commit_log_possible_stack_dump)) {
-			WARN("COMMIT_LOG_LONG_LINE",
-			     "Possible unwrapped commit description (prefer a maximum 75 chars per line)\n" . $herecurr);
+			if ($line =~ /(?:http|https|ftp):\/\//) {
+				WARN("COMMIT_LOG_LONG_LINE",
+				     "Consider prefixing the URL with 'Link:'\n" . $herecurr);
+			}
+			else {
+				WARN("COMMIT_LOG_LONG_LINE",
+				     "Possible unwrapped commit description (prefer a maximum 75 chars per line)\n" . $herecurr);
+			}
 			$commit_log_long_line = 1;
 		}
 
-- 
2.17.1