Modifiers %h and %hh should never be used.
Commit cbacb5ab0aa0 ("docs: printk-formats: Stop encouraging use
of unnecessary %h[xudi] and %hh[xudi]") specifies that:
"Standard integer promotion is already done and %hx and %hhx is useless
so do not encourage the use of %hh[xudi] or %h[xudi]."
"The "h" and "hh" things should never be used. The only reason for them
being used if you have an "int", but you want to print it out as a
"char" (and honestly, that is a really bad reason, you'd be better off
just using a proper cast to make the code more obvious)."
Add a new check to emit a warning on finding an unneeded use of %h or
%hh modifier.
Link:
https://lore.kernel.org/lkml/[email protected]/
Suggested-by: Lukas Bulwahn <[email protected]>
Signed-off-by: Dwaipayan Ray <[email protected]>
---
Changes in v2:
- Use $logFunctions instead of the manual list.
- Relocate the check to after logging continuations check.
- Remove perl_version_ok condition which is unneeded here.
scripts/checkpatch.pl | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 7dc094445d83..d1ecb852f384 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6027,6 +6027,18 @@ sub process {
"Avoid logging continuation uses where feasible\n"
. $herecurr);
}
+# check for unnecessary use of %h[xudi] and %hh[xudi] in logging functions
+ if (defined $stat &&
+ $line =~ /\b$logFunctions\s*\(/) {
+ my $lc = $stat =~ tr@\n@@;
+ $lc = $lc + $linenr;
+ my $stat_real = get_stat_real($linenr, $lc);
+ if ($stat_real =~ /\"[^\"]*%[\d\.\*\-]*h+[idux].*\"/i) {
+ WARN("UNNECESSARY_MODIFIER",
+ "Unnecessary use of modifiers %h[xudi] or
%hh[xudi]\n" . "$here\n$stat_real\n");
+ }
+ }
+
# check for mask then right shift without a parentheses
if ($perl_version_ok &&
$line =~ /$LvalOrFunc\s*\&\s*($LvalOrFunc)\s*>>/ &&
--
2.27.0
