From patchwork Thu Dec 19 08:43:50 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Stefan Haberland X-Patchwork-Id: 11302829 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 901AE1892 for ; Thu, 19 Dec 2019 08:44:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 77B4824679 for ; Thu, 19 Dec 2019 08:44:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726622AbfLSIoA (ORCPT ); Thu, 19 Dec 2019 03:44:00 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:39886 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726652AbfLSIoA (ORCPT ); Thu, 19 Dec 2019 03:44:00 -0500 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id xBJ8gdhs140240 for ; Thu, 19 Dec 2019 03:43:59 -0500 Received: from e06smtp02.uk.ibm.com (e06smtp02.uk.ibm.com [195.75.94.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 2wyq5r3agh-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 19 Dec 2019 03:43:59 -0500 Received: from localhost by e06smtp02.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 19 Dec 2019 08:43:54 -0000 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id xBJ8hr6Y33030254 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 19 Dec 2019 08:43:53 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0105942045; Thu, 19 Dec 2019 08:43:53 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EBB7A4204B; Thu, 19 Dec 2019 08:43:52 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Thu, 19 Dec 2019 08:43:52 +0000 (GMT) Received: by tuxmaker.boeblingen.de.ibm.com (Postfix, from userid 20191) id 8C790E02BE; Thu, 19 Dec 2019 09:43:52 +0100 (CET) From: Stefan Haberland To: axboe@kernel.dk Cc: linux-block@vger.kernel.org, hoeppner@linux.ibm.com, linux-s390@vger.kernel.org, heiko.carstens@de.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com Subject: [PATCH 1/3] s390/dasd/cio: Interpret ccw_device_get_mdc return value correctly Date: Thu, 19 Dec 2019 09:43:50 +0100 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191219084352.75114-1-sth@linux.ibm.com> References: <20191219084352.75114-1-sth@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 x-cbid: 19121908-0008-0000-0000-000003427D49 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19121908-0009-0000-0000-00004A629571 Message-Id: <20191219084352.75114-2-sth@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-12-18_08:2019-12-17,2019-12-18 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 spamscore=0 adultscore=0 suspectscore=1 bulkscore=0 impostorscore=0 priorityscore=1501 lowpriorityscore=0 clxscore=1015 phishscore=0 mlxlogscore=916 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1912190074 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Jan Höppner The max data count (mdc) is an unsigned 16-bit integer value as per AR documentation and is received via ccw_device_get_mdc() for a specific path mask from the CIO layer. The function itself also always returns a positive mdc value or 0 in case mdc isn't supported or couldn't be determined. Though, the comment for this function describes a negative return value to indicate failures. As a result, the DASD device driver interprets the return value of ccw_device_get_mdc() incorrectly. The error case is essentially a dead code path. To fix this behaviour, check explicitly for a return value of 0 and change the comment for ccw_device_get_mdc() accordingly. This fix merely enables the error code path in the DASD functions get_fcx_max_data() and verify_fcx_max_data(). The actual functionality stays the same and is still correct. Signed-off-by: Jan Höppner Acked-by: Peter Oberparleiter Reviewed-by: Stefan Haberland Signed-off-by: Stefan Haberland Reviewed-by: Cornelia Huck --- drivers/s390/block/dasd_eckd.c | 9 +++++---- drivers/s390/cio/device_ops.c | 2 +- 2 files changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c index c94184d080f8..f5622f4a2ecf 100644 --- a/drivers/s390/block/dasd_eckd.c +++ b/drivers/s390/block/dasd_eckd.c @@ -1128,7 +1128,8 @@ static u32 get_fcx_max_data(struct dasd_device *device) { struct dasd_eckd_private *private = device->private; int fcx_in_css, fcx_in_gneq, fcx_in_features; - int tpm, mdc; + unsigned int mdc; + int tpm; if (dasd_nofcx) return 0; @@ -1142,7 +1143,7 @@ static u32 get_fcx_max_data(struct dasd_device *device) return 0; mdc = ccw_device_get_mdc(device->cdev, 0); - if (mdc < 0) { + if (mdc == 0) { dev_warn(&device->cdev->dev, "Detecting the maximum supported data size for zHPF requests failed\n"); return 0; } else { @@ -1153,12 +1154,12 @@ static u32 get_fcx_max_data(struct dasd_device *device) static int verify_fcx_max_data(struct dasd_device *device, __u8 lpm) { struct dasd_eckd_private *private = device->private; - int mdc; + unsigned int mdc; u32 fcx_max_data; if (private->fcx_max_data) { mdc = ccw_device_get_mdc(device->cdev, lpm); - if ((mdc < 0)) { + if (mdc == 0) { dev_warn(&device->cdev->dev, "Detecting the maximum data size for zHPF " "requests failed (rc=%d) for a new path %x\n", diff --git a/drivers/s390/cio/device_ops.c b/drivers/s390/cio/device_ops.c index 65841af15748..ccecf6b9504e 100644 --- a/drivers/s390/cio/device_ops.c +++ b/drivers/s390/cio/device_ops.c @@ -635,7 +635,7 @@ EXPORT_SYMBOL(ccw_device_tm_start_timeout); * @mask: mask of paths to use * * Return the number of 64K-bytes blocks all paths at least support - * for a transport command. Return values <= 0 indicate failures. + * for a transport command. Return value 0 indicates failure. */ int ccw_device_get_mdc(struct ccw_device *cdev, u8 mask) {