From patchwork Tue Dec 15 14:25:27 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jisheng Zhang X-Patchwork-Id: 7855001 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id D6FFABEEE1 for ; Tue, 15 Dec 2015 14:31:27 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 1B83B2037C for ; Tue, 15 Dec 2015 14:31:27 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 31F62202BE for ; Tue, 15 Dec 2015 14:31:26 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1a8qbl-0005UM-W7; Tue, 15 Dec 2015 14:29:42 +0000 Received: from mx0b-0016f401.pphosted.com ([67.231.156.173]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1a8qbg-0004qr-FD for linux-arm-kernel@lists.infradead.org; Tue, 15 Dec 2015 14:29:37 +0000 Received: from pps.filterd (m0045851.ppops.net [127.0.0.1]) by mx0b-0016f401.pphosted.com (8.15.0.59/8.15.0.59) with SMTP id tBFESp47032163; Tue, 15 Dec 2015 06:29:10 -0800 Received: from sc-exch04.marvell.com ([199.233.58.184]) by mx0b-0016f401.pphosted.com with ESMTP id 1ytmnpr010-1 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT); Tue, 15 Dec 2015 06:29:10 -0800 Received: from SC-EXCH04.marvell.com (10.93.176.84) by SC-EXCH04.marvell.com (10.93.176.84) with Microsoft SMTP Server (TLS) id 15.0.1104.5; Tue, 15 Dec 2015 06:29:08 -0800 Received: from maili.marvell.com (10.93.176.43) by SC-EXCH04.marvell.com (10.93.176.84) with Microsoft SMTP Server id 15.0.1104.5 via Frontend Transport; Tue, 15 Dec 2015 06:29:08 -0800 Received: from xhacker.marvell.com (unknown [10.37.135.134]) by maili.marvell.com (Postfix) with ESMTP id CF23E3F703F; Tue, 15 Dec 2015 06:29:07 -0800 (PST) From: Jisheng Zhang To: Subject: [PATCH] watchdog: dw_wdt: fix signedness bug in dw_wdt_top_in_seconds() Date: Tue, 15 Dec 2015 22:25:27 +0800 Message-ID: <1450189527-1015-1-git-send-email-jszhang@marvell.com> X-Mailer: git-send-email 2.6.4 MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2015-12-15_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=inbound_notspam policy=inbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1507310007 definitions=main-1512150243 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20151215_062936_749305_0D3924CB X-CRM114-Status: GOOD ( 10.24 ) X-Spam-Score: -2.6 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jisheng Zhang , sebastian.hesselbarth@gmail.com, linux-watchdog@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On 64bit platforms, "(1 << (16 + top)) / clk_get_rate(dw_wdt.clk)" is sign-extended to 64bit then converted to unsigned 64bit, finally divide the clk rate. If the top is the maximum TOP i.e 15, "(1 << (16 +15))" will be sign-extended to 0xffffffff80000000, then converted to unsigned 0xffffffff80000000, which is a huge number, thus the final result is wrong. We fix this issue by giving usigned value(1U in this case) at first. Let's assume clk rate is 25MHZ, Before the patch: dw_wdt_top_in_seconds(15) = -864612050 After the patch: dw_wdt_top_in_seconds(15) = 85 Signed-off-by: Jisheng Zhang Reviewed-by: Guenter Roeck --- drivers/watchdog/dw_wdt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c index 6ea0634..8fefa4ad 100644 --- a/drivers/watchdog/dw_wdt.c +++ b/drivers/watchdog/dw_wdt.c @@ -81,7 +81,7 @@ static inline int dw_wdt_top_in_seconds(unsigned top) * There are 16 possible timeout values in 0..15 where the number of * cycles is 2 ^ (16 + i) and the watchdog counts down. */ - return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk); + return (1U << (16 + top)) / clk_get_rate(dw_wdt.clk); } static int dw_wdt_get_top(void)