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/4910042649a4f3ab22fac93191b8c1fa0a2e17c3.ca...@perches.com/ Suggested-by: Lukas Bulwahn <lukas.bulw...@gmail.com> Signed-off-by: Dwaipayan Ray <dwaipayanr...@gmail.com> --- scripts/checkpatch.pl | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 7dc094445d83..47c1017a9973 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -6570,6 +6570,19 @@ sub process { } } +# check for unnecessary use of %h[xudi] and %hh[xudi] + if ($perl_version_ok && + defined $stat && + $line =~ /(?:[sd]?print[kfd]|(?:pr_|drm_)(?:info|debug|warn|error))/i) { + 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 length modifiers %h[xudi] or %hh[xudi]\n" . "$here\n$stat_real\n"); + } + } + # check for naked sscanf if ($perl_version_ok && defined $stat && -- 2.27.0