checkpatch: warn on comparisons to jiffies

Comparing jiffies is almost always wrong and time_before and time_after
should be used instead.

Warn on any comparison to jiffies.

Signed-off-by: Joe Perches <joe@perches.com>
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 576139a..c274e1d 100755 (executable)
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3299,6 +3299,12 @@ sub process {
                        }
                }
 
+# check for comparisons of jiffies
+               if ($line =~ /\bjiffies\s*$Compare|$Compare\s*jiffies\b/) {
+                       WARN("JIFFIES_COMPARISON",
+                            "Comparing jiffies is almost always wrong; prefer time_after, time_before and friends\n" . $herecurr);
+               }
+
 # warn about #ifdefs in C files
 #              if ($line =~ /^.\s*\#\s*if(|n)def/ && ($realfile =~ /\.c$/)) {
 #                      print "#ifdef in C files should be avoided\n";