[PATCH] checkpatch: check for missing \n at the end of logging message

[Christophe JAILLET]

Strings logged with pr_xxx and dev_xxx often lack a trailing '\n'.
Introduce new tests to try to catch them early.

Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
---
This is more a PoC for now.

Regex could be improved, merged, ...
We could also check for surrounding pr_cont...

This patch is based on idea from [1]. coccinelle spots too many places
where \n are missing (~ 2800 with the heuristic I've used).
Fixing them would be painful.
I instead propose to teach checkpatch.pl about it to try to spot cases
early and avoid introducing new cases.

[1]: https://marc.info/?l=kernel-janitors&m=158619533629657&w=4
---
 scripts/checkpatch.pl | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index c392ab8ea12e..792804bd6ad9 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -5676,6 +5676,16 @@ sub process {
 			}
 		}
 
+# check for missing \n at the end of logging function
+		if ($line =~ /\bpr_(emerg|alert|crit|err|warning|warn|notice|info|debug|dbg)\s*\("([^"]*(?<!\\n))"/) {
+			WARN("MISSING NL",
+			     "Possible missing '\\n' at the end of a log message\n" . $hereprev);
+		}
+		if ($line =~ /\bdev_(emerg|alert|crit|err|warning|warn|notice|info|debug|dbg)\s*\([^,]*,\s*"([^"]*(?<!\\n))"/) {
+			WARN("MISSING NL",
+			     "Possible missing '\\n' at the end of a log message\n" . $hereprev);
+		}
+
 # check for logging functions with KERN_<LEVEL>
 		if ($line !~ /printk(?:_ratelimited|_once)?\s*\(/ &&
 		    $line =~ /\b$logFunctions\s*\(.*\b(KERN_[A-Z]+)\b/) {
-- 
2.20.1