On Thu, 2020-11-26 at 12:58 +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.
>
> Link:
> https://lore.kernel.org/lkml/[email protected]/
>
> Suggested-by: Lukas Bulwahn <[email protected]>
> Signed-off-by: Dwaipayan Ray <[email protected]>
> ---
> 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) {
Use $logFunctions and please move this close to the lines with
"# check for logging functions with KERN_<LEVEL>"
> + 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 &&
