Comparisons of A to true and false are better written
as A and !A.

Bleat a message on use.

Signed-off-by: Joe Perches <j...@perches.com>
---
 scripts/checkpatch.pl | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 3fb6d86..080e7f6 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3538,6 +3538,23 @@ sub process {
                             "Using yield() is generally wrong. See yield() 
kernel-doc (sched/core.c)\n"  . $herecurr);
                }
 
+# check for comparisons against true and false
+               if ($line =~ 
/\+\s*(.*?)($Lval)\s*(==|\!=)\s*(true|false)\b(.*)$/i) {
+                       my $lead = $1;
+                       my $arg = $2;
+                       my $test = $3;
+                       my $otype = $4;
+                       my $trail = $5;
+                       my $type = lc($otype);
+                       my $op = "!";
+                       if (("$test" eq "==" && "$type" eq "true") ||
+                           ("$test" eq "!=" && "$type" eq "false")) {
+                               $op = "";
+                       }
+                       WARN("BOOL_COMPARISON",
+                            "Using comparison to $otype is poor style. Use 
'${lead}${op}${arg}${trail}'\n" . $herecurr);
+               }
+
 # check for semaphores initialized locked
                if ($line =~ /^.\s*sema_init.+,\W?0\W?\)/) {
                        WARN("CONSIDER_COMPLETION",


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