From 70eb2275ff8e0b4cafe67176674d580c987c071d Mon Sep 17 00:00:00 2001 From: Dwaipayan Ray Date: Tue, 15 Dec 2020 20:45:15 -0800 Subject: [PATCH] checkpatch: add warning for unnecessary use of %h[xudi] and %hh[xudi] 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. Also add a fix option to the check. Link: https://lore.kernel.org/lkml/4910042649a4f3ab22fac93191b8c1fa0a2e17c3.camel@perches.com/ Link: https://lkml.kernel.org/r/20201128200046.78739-1-dwaipayanray1@gmail.com Signed-off-by: Dwaipayan Ray Suggested-by: Joe Perches Suggested-by: Lukas Bulwahn Acked-by: Joe Perches Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- scripts/checkpatch.pl | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index d7616a6f1436..2716b9bfc0c2 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -6102,6 +6102,28 @@ 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*\(/ && + index($stat, '"') >= 0) { + my $lc = $stat =~ tr@\n@@; + $lc = $lc + $linenr; + my $stat_real = get_stat_real($linenr, $lc); + pos($stat_real) = index($stat_real, '"'); + while ($stat_real =~ /[^\"%]*(%[\#\d\.\*\-]*(h+)[idux])/g) { + my $pspec = $1; + my $h = $2; + my $lineoff = substr($stat_real, 0, $-[1]) =~ tr@\n@@; + if (WARN("UNNECESSARY_MODIFIER", + "Integer promotion: Using '$h' in '$pspec' is unnecessary\n" . "$here\n$stat_real\n") && + $fix && $fixed[$fixlinenr + $lineoff] =~ /^\+/) { + my $nspec = $pspec; + $nspec =~ s/h//g; + $fixed[$fixlinenr + $lineoff] =~ s/\Q$pspec\E/$nspec/; + } + } + } + # check for mask then right shift without a parentheses if ($perl_version_ok && $line =~ /$LvalOrFunc\s*\&\s*($LvalOrFunc)\s*>>/ && -- 2.34.1