[PATCH 4/4] Checkpatch: warn about unexpectedly long msleep's

[Patrick Pannuto <ppannuto@codeaurora.org>]

As explained in Documentation/timers/delays.txt, msleep's
of < 20ms may sleep for as long as 20ms. Caller's of
msleep(1) or msleep(2), etc are likely not to expect this
quirky behavior - warn them.

Signed-off-by: Patrick Pannuto <ppannuto@codeaurora.org>
---
 scripts/checkpatch.pl |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 0650ab9..bbc2e76 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2583,6 +2583,13 @@ sub process {
 			WARN("usleep_range is preferred over usleep; see Documentation/timers/delays.txt\n" . $line);
 		}
 
+# warn about unexpectedly long msleep's
+		if ($line =~ /\bmsleep\s*\((\d+)\);/) {
+			if ($1 < 20) {
+				WARN("msleep < 20ms can sleep for up to 20ms; see Documentation/timers/delays.txt\n" . $line);
+			}
+		}
+
 # warn about #ifdefs in C files
 #		if ($line =~ /^.\s*\#\s*if(|n)def/ && ($realfile =~ /\.c$/)) {
 #			print "#ifdef in C files should be avoided\n";
-- 
1.7.2