From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932464Ab2JJXBV (ORCPT ); Wed, 10 Oct 2012 19:01:21 -0400 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:49610 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756880Ab2JJXBQ (ORCPT ); Wed, 10 Oct 2012 19:01:16 -0400 X-Sasl-enc: KOGVeMi9X+b79TKAmkSZdwS8go69c9pdXrpPqm/GaG0y 1349910075 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, Martin Michlmayr , Jonathan Nieder , James Bottomley , Andrew Morton , Linus Torvalds Subject: [ 019/122] drivers/scsi/atp870u.c: fix bad use of udelay Date: Thu, 11 Oct 2012 07:53:05 +0900 Message-Id: <20121010225341.591800360@linuxfoundation.org> X-Mailer: git-send-email 1.8.0.rc0.18.gf84667d In-Reply-To: <20121010225337.989799482@linuxfoundation.org> References: <20121010225337.989799482@linuxfoundation.org> User-Agent: quilt/0.60-2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Martin Michlmayr commit 0f6d93aa9d96cc9022b51bd10d462b03296be146 upstream. The ACARD driver calls udelay() with a value > 2000, which leads to to the following compilation error on ARM: ERROR: "__bad_udelay" [drivers/scsi/atp870u.ko] undefined! make[1]: *** [__modpost] Error 1 This is because udelay is defined on ARM, roughly speaking, as #define udelay(n) ((n) > 2000 ? __bad_udelay() : \ __const_udelay((n) * ((2199023U*HZ)>>11))) The argument to __const_udelay is the number of jiffies to wait divided by 4, but this does not work unless the multiplication does not overflow, and that is what the build error is designed to prevent. The intended behavior can be achieved by using mdelay to call udelay multiple times in a loop. [jrnieder@gmail.com: adding context] Signed-off-by: Martin Michlmayr Signed-off-by: Jonathan Nieder Cc: James Bottomley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/atp870u.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) --- a/drivers/scsi/atp870u.c +++ b/drivers/scsi/atp870u.c @@ -1173,7 +1173,16 @@ wait_io1: outw(val, tmport); outb(2, 0x80); TCM_SYNC: - udelay(0x800); + /* + * The funny division into multiple delays is to accomodate + * arches like ARM where udelay() multiplies its argument by + * a large number to initialize a loop counter. To avoid + * overflow, the maximum supported udelay is 2000 microseconds. + * + * XXX it would be more polite to find a way to use msleep() + */ + mdelay(2); + udelay(48); if ((inb(tmport) & 0x80) == 0x00) { /* bsy ? */ outw(0, tmport--); outb(0, tmport);