On Sat, 2020-11-28 at 23:08 +0530, Dwaipayan Ray wrote:
> 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/[email protected]/
>
> Suggested-by: Joe Perches <[email protected]>
> Suggested-by: Lukas Bulwahn <[email protected]>
> Signed-off-by: Dwaipayan Ray <[email protected]>
> ---
> Changes in v3:
> - Change warning message
> - Fix regex match to include capture group
> - Warn on every unnecesary use of %h on a line
> - Add fix option when the format line matches current line
>
> Changes in v2:
> - Use $logFunctions instead of the manual list.
> - Relocate the check to after logging continuations check.
> - Remove perl_version_ok check
>
> scripts/checkpatch.pl | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 7dc094445d83..dc25d32f0c5f 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -6027,6 +6027,22 @@ 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@@;
> + for (my $cur_ln = $linenr; $cur_ln <= $linenr + $lc;
> $cur_ln++) {
> + my $cur_rawline = raw_line($cur_ln, 0);
> + while ($cur_rawline =~
> /^\+.*\"[^\"]*(%[\d\.\*\-]*h+[idux])/g) {
> + if (WARN("INTEGER_PROMOTION",
> + "Using 'h' in $1 is
> unnecessary\n" . "$cur_rawline\n") &&
> + $fix && ($cur_ln == $linenr)) {
> + $fixed[$fixlinenr] =~
> s/(\"[^\"]*%[\d\.\*\-]*)h+([idux])/$1$2/;
> + }
> + }
> + }
> + }
> +
Here was what I tried:
There are uses like %#06hh", so # was addedto the format block
and multiple line uses were also inspected.
scripts/checkpatch.pl | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 7dc094445d83..b985b6b37ba8 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6027,6 +6027,29 @@ 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, '"');
+ my $lineoff = substr($stat_real, 0, pos($stat_real)) =~
tr/\n//;
+ while ($stat_real =~
/[^"%]*(%[#\d\.\*\-]*(h+)[idux])/g) {
+ my $pspec = $1;
+ my $h = $2;
+ if (WARN("UNNECESSARY_MODIFIER",
+ "Integer promotion: '$h' use 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*>>/ &&
