Messages in this thread Patch in this message |  | | From | Dwaipayan Ray <> | Subject | [PATCH v3] checkpatch: add warning for unnecessary use of %h[xudi] and %hh[xudi] | Date | Sat, 28 Nov 2020 23:08:50 +0530 |
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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/
Suggested-by: Joe Perches <joe@perches.com> Suggested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com> Signed-off-by: Dwaipayan Ray <dwaipayanray1@gmail.com> --- 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$2/; + } + } + } + } + # check for mask then right shift without a parentheses if ($perl_version_ok && $line =~ /$LvalOrFunc\s*\&\s*($LvalOrFunc)\s*>>/ && -- 2.27.0
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