linux-kernel - [PATCH] checkpatch: Prefer ftrace over function entry/exit printks

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Date:   Fri, 08 Jan 2021 10:32:29 -0800
From:   Joe Perches <joe@...ches.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Dan Carpenter <dan.carpenter@...cle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] checkpatch: Prefer ftrace over function entry/exit printks

Prefer using ftrace over function entry/exit logging messages.

Warn with various function entry/exit only logging that only
use __func__ with or without descriptive decoration.

Signed-off-by: Joe Perches <joe@...ches.com>
---
 scripts/checkpatch.pl | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index e6857bdfcb2d..7c95f23352ae 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -507,6 +507,30 @@ our $signature_tags = qr{(?xi:
 	Cc:
 )};
 
+our $tracing_logging_tags = qr{(?xi:
+	[=-]*> |
+	<[=-]* |
+	\[ |
+	\] |
+	start |
+	called |
+	entered |
+	entry |
+	enter |
+	in |
+	inside |
+	here |
+	begin |
+	exit |
+	end |
+	done |
+	leave |
+	completed |
+	out |
+	return |
+	[\.\!:\s]*
+)};
+
 sub edit_distance_min {
 	my (@arr) = @_;
 	my $len = scalar @arr;
@@ -5981,6 +6005,17 @@ sub process {
 			     "Prefer using '\"%s...\", __func__' to using '$context_function', this function's name, in a string\n" . $herecurr);
 		}
 
+# check for unnecessary function tracing like uses
+# This does not use $logFunctions because there are many instances like
+# 'dprintk(FOO, "%s()\n", __func__);' which do not match $logFunctions
+		if ($rawline =~ /^\+.*\([^"]*"$tracing_logging_tags{0,3}%s(?:\s*\(\s*\)\s*)?$tracing_logging_tags{0,3}(?:\\n)?"\s*,\s*__func__\s*\)\s*;/) {
+			if (WARN("TRACING_LOGGING",
+				 "Unnecessary ftrace-like logging - prefer using ftrace\n" . $herecurr) &&
+			    $fix) {
+                                fix_delete_line($fixlinenr, $rawline);
+			}
+		}
+
 # check for spaces before a quoted newline
 		if ($rawline =~ /^.*\".*\s\\n/) {
 			if (WARN("QUOTED_WHITESPACE_BEFORE_NEWLINE",