[RFC PATCH V2] checkpatch: Check output format style of __func__ uses

[Joe Perches <joe@perches.com>]

Loggng messages that emit function names have many different forms.
Perhaps it'd be better for logging consistency and grep ease to
exclusively use "%s:"

As well, function tracing logging uses are generally unnecessary given
the kernel's function tracing (ftrace) capability.

Right now, grep shows these mixtures of forms:

13704	"%s:"
3839	"%s "
2787	"%s()"

Some of these are macros definitions of various styles.

Unfortunately, given the complexity of these macro definition styles,
checkpatch isn't an ideal tool to find these macros.

Maybe a coccinelle script might be better suited to find and fix all
the various types of uses.

Add a --fix option for these logging messages with __func__.

Signed-off-by: Joe Perches <joe@perches.com>
---

v2: Warn on function tracing logging
    Add --fix option

 scripts/checkpatch.pl | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 75ce6d0..b695f75 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1415,6 +1415,22 @@ sub raw_line {
 	return $line;
 }
 
+sub cooked_line {
+	my ($linenr, $cnt) = @_;
+
+	my $offset = $linenr - 1;
+	$cnt++;
+
+	my $line;
+	while ($cnt) {
+		$line = $lines[$offset++];
+		next if (defined($line) && $line =~ /^-/);
+		$cnt--;
+	}
+
+	return $line;
+}
+
 sub cat_vet {
 	my ($vet) = @_;
 	my ($res, $coded);
@@ -5681,6 +5697,45 @@ sub process {
 			}
 		}
 
+# check how __func__ is formatted, prefer "%s:...',  __func__
+		if ($^V && $^V ge 5.10.0 &&
+		    defined $stat &&
+		    $stat =~ /\b__func__\b/ &&
+		    $stat =~ /^\+\s*$logFunctions\s*\(\s*[^"]*$String\s*,\s*__func__\b/m &&
+		    (() = $stat =~ /^\+|\n\+/g) == 1 &&
+		    (() = $stat =~ /;/g) <= 1) {
+			my $herectx = $here . "\n";
+			my $cooked_linenr = -1;
+			my $cooked_line = "";
+			my $raw_line = "";
+			my $cnt = statement_rawlines($stat);
+			for (my $n = 0; $n < $cnt; $n++) {
+				$herectx .= raw_line($linenr, $n) . "\n";
+				if ($cooked_linenr == -1 && cooked_line($linenr, $n) =~ /$String/) {
+					$cooked_linenr = $linenr + $n;
+					$cooked_line = cooked_line($linenr, $n);
+					$raw_line = raw_line($linenr, $n);
+				}
+			}
+			my $qs = get_quoted_string($cooked_line, $raw_line);
+			if ($qs =~ /^"\s*%s(?:[\s:\-]*|[\s:\-]*\(\s*\)\s*[\s:\-]*)?(?:enter|entering|entered|exit|exiting)?\s*\.*\s*\\n"$/i) {
+				if (WARN("FUNC_STYLE",
+					 "Prefer using ftrace to logging function entry/exit\n" . $herectx) &&
+				     $cnt == 1 &&
+				     $fix) {
+					fix_delete_line($fixlinenr, $rawline);
+				}
+			} elsif ($qs !~ /^"%s:/) {
+				if (WARN("FUNC_STYLE",
+					 "Prefer using formatting style '%s:' for __func__\n" . $herectx) &&
+				    $fix) {
+					$fixed[$cooked_linenr - 1] =~ s/[:\s]*%s(?:[:\s,\-]*|[\s:\-]*\(\s*\)\s*[\s:\-]*)?//;
+					$fixed[$cooked_linenr - 1] =~ s/"/"%s: /;
+					$fixed[$cooked_linenr - 1] =~ s/"%s: \\n/"%s\\n/;
+				}
+			}
+		}
+
 # check for uses of __DATE__, __TIME__, __TIMESTAMP__
 		while ($line =~ /\b(__(?:DATE|TIME|TIMESTAMP)__)\b/g) {
 			ERROR("DATE_TIME",
-- 
2.6.3.368.gf34be46