[PATCH v5] checkpatch: Tolerate upstream commit references

[Petr Machata <petrm@nvidia.com>]

Two forms of upstream commit references are used (and documented) for
stable kernels:

- [ Upstream commit <sha1> ]
- commit <sha1> upstream.

Extend checkpatch so that it doesn't cite these. This reduces noise that
downstream maintainers experience when checkpatching patches that may
contain commit references of this sort.

In order to future-proof the script, allow also permutations of the above
styles: with a period or without, bracketed or not, capitalized or not. The
hash is recognized as at least 7 digits long, similarly to the "This
reverts commit" exclude below.

Signed-off-by: Petr Machata <petrm@nvidia.com>
---

Notes:
    v5:
    - No changes, just a ping.
    
    v4:
    - No changes, just a ping.
    
    v3:
    - Tolerate a couple more upstream commit reference styles.
    
    v2:
    - No changes, just a ping.

 scripts/checkpatch.pl | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e722dd6fa8ef..53b21b4a4760 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3352,6 +3352,8 @@ sub process {
 		if ($perl_version_ok &&
 		    $in_commit_log && !$commit_log_possible_stack_dump &&
 		    $line !~ /^\s*(?:Link|Patchwork|http|https|BugLink|base-commit):/i &&
+		    $line !~ /^(\[\s*)?[Uu]pstream commit [0-9a-f]{7,40}\.?(\s*])?/ &&
+		    $line !~ /^(\[\s*)?[Cc]ommit\s*[0-9a-f]{7,40}\s*upstream\.?(\s*])?/ &&
 		    $line !~ /^This reverts commit [0-9a-f]{7,40}/ &&
 		    (($line =~ /\bcommit\s+[0-9a-f]{5,}\b/i ||
 		      ($line =~ /\bcommit\s*$/i && defined($rawlines[$linenr]) && $rawlines[$linenr] =~ /^\s*[0-9a-f]{5,}\b/i)) ||
-- 
2.49.0