Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757510AbcJNOUO (ORCPT ); Fri, 14 Oct 2016 10:20:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57208 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754307AbcJNOUF (ORCPT ); Fri, 14 Oct 2016 10:20:05 -0400 From: Denys Vlasenko To: James Bottomley Cc: Denys Vlasenko , Hannes Reinicke , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] scsi: aic7xxx: fix ahc_delay and ahd_delay Date: Fri, 14 Oct 2016 16:20:00 +0200 Message-Id: <20161014142000.18833-1-dvlasenk@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 14 Oct 2016 14:20:05 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1732 Lines: 63 They are buggy: while (usec > 0) udelay(usec % 1024); usec -= 1024; For example, for usec = 100*1024 + 1, old code will udelay(1) 101 times, i.e. it will be approximately equivalent to udelay(101), not the expected udelay(102400). This did not bite because all callers use values far from "pathological" ones, such as 500 and 1000 - these work fine with buggy code. This was reported in 2006 but was missed. Signed-off-by: Denys Vlasenko CC: James Bottomley CC: Hannes Reinicke CC: linux-scsi@vger.kernel.org CC: linux-kernel@vger.kernel.org --- drivers/scsi/aic7xxx/aic79xx_osm.c | 7 ++++--- drivers/scsi/aic7xxx/aic7xxx_osm.c | 7 ++++--- 2 files changed, 8 insertions(+), 6 deletions(-) diff --git a/drivers/scsi/aic7xxx/aic79xx_osm.c b/drivers/scsi/aic7xxx/aic79xx_osm.c index 2588b8f..e7a7838 100644 --- a/drivers/scsi/aic7xxx/aic79xx_osm.c +++ b/drivers/scsi/aic7xxx/aic79xx_osm.c @@ -380,9 +380,10 @@ ahd_delay(long usec) * multi-millisecond waits. Wait at most * 1024us per call. */ - while (usec > 0) { - udelay(usec % 1024); - usec -= 1024; + udelay(usec & 1023); + usec >>= 10; + while (--usec >= 0) { + udelay(1024); } } diff --git a/drivers/scsi/aic7xxx/aic7xxx_osm.c b/drivers/scsi/aic7xxx/aic7xxx_osm.c index fc6a831..c81798e 100644 --- a/drivers/scsi/aic7xxx/aic7xxx_osm.c +++ b/drivers/scsi/aic7xxx/aic7xxx_osm.c @@ -388,9 +388,10 @@ ahc_delay(long usec) * multi-millisecond waits. Wait at most * 1024us per call. */ - while (usec > 0) { - udelay(usec % 1024); - usec -= 1024; + udelay(usec & 1023); + usec >>= 10; + while (--usec >= 0) { + udelay(1024); } } -- 2.9.2