linux-kernel - [PATCH] checkpatch: Add test for long udelay

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Date:	Tue, 04 Feb 2014 04:59:25 -0800
From:	Joe Perches <joe@...ches.com>
To:	Holger Schurig <holgerschurig@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Cc:	Sujith Manoharan <sujith@...jith.org>,
	ath9k-devel <ath9k-devel@...ts.ath9k.org>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	John Linville <linville@...driver.com>
Subject: [PATCH] checkpatch: Add test for long udelay

On Tue, 2014-02-04 at 08:03 +0100, Holger Schurig wrote:
> The macro udelay
> cannot handle large values because of lost-of-precision.
> 
> IMHO udelay on ARM is broken, because it also cannot work with fast
> ARM processors (where bogomips >= 3355, which is in sight now). It's
> just not broken enought that someone did something against it ...   so
> the current kludge is good enought.

Until then, warn on long udelay uses.

Also fix uses of $line that should have been $herecurr.

Signed-off-by: Joe Perches <joe@...ches.com>
---
 scripts/checkpatch.pl | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 0ea2a1e..36275c5 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3912,10 +3912,15 @@ sub process {
 
 # prefer usleep_range over udelay
 		if ($line =~ /\budelay\s*\(\s*(\d+)\s*\)/) {
+			my $delay = $1;
 			# ignore udelay's < 10, however
-			if (! ($1 < 10) ) {
+			if (! ($delay < 10) ) {
 				CHK("USLEEP_RANGE",
-				    "usleep_range is preferred over udelay; see Documentation/timers/timers-howto.txt\n" . $line);
+				    "usleep_range is preferred over udelay; see Documentation/timers/timers-howto.txt\n" . $herecurr);
+			}
+			if ($delay > 2000) {
+				WARN("LONG_UDELAY",
+				     "long udelay - prefer mdelay; see arch/arm/include/asm/delay.h\n" . $herecurr);
 			}
 		}
 
@@ -3923,7 +3928,7 @@ sub process {
 		if ($line =~ /\bmsleep\s*\((\d+)\);/) {
 			if ($1 < 20) {
 				WARN("MSLEEP",
-				     "msleep < 20ms can sleep for up to 20ms; see Documentation/timers/timers-howto.txt\n" . $line);
+				     "msleep < 20ms can sleep for up to 20ms; see Documentation/timers/timers-howto.txt\n" . $herecurr);
 			}
 		}
 


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