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.

Link: https://lkml.kernel.org/r/47c01081533a417c99c9a80a4cd537f8c308503f.camel@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 345879a..736129c 100755 (executable)
--- 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 $len = scalar @arr;
@@ -5972,6 +5996,17 @@ sub process {
                             "Prefer using '\"%s...\", __func__' to using '$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",