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>

1 files changed, 6 insertions, 0 deletions

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 576139a508a3..c274e1dc1e67 100755
--- 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";