From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 025ABC43613 for ; Mon, 24 Jun 2019 15:13:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C9EB520652 for ; Mon, 24 Jun 2019 15:13:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730549AbfFXPNh (ORCPT ); Mon, 24 Jun 2019 11:13:37 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:50876 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729235AbfFXPNg (ORCPT ); Mon, 24 Jun 2019 11:13:36 -0400 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x5OF0Eaw130558 for ; Mon, 24 Jun 2019 11:13:35 -0400 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0b-001b2d01.pphosted.com with ESMTP id 2tb0dr2df9-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 24 Jun 2019 11:13:34 -0400 Received: from localhost by e06smtp07.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) Mon, 24 Jun 2019 16:13:26 +0100 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x5OFDPht43974882 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 24 Jun 2019 15:13:25 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5A448AE053; Mon, 24 Jun 2019 15:13:25 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7827FAE045; Mon, 24 Jun 2019 15:13:24 +0000 (GMT) Received: from oc4120165700.ibm.com (unknown [9.152.98.199]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 24 Jun 2019 15:13:24 +0000 (GMT) Subject: Re: [PATCH V5 10/16] s390: zfcp_fc: use sg helper to operate scatterlist To: Ming Lei , linux-scsi@vger.kernel.org, "Martin K . Petersen" Cc: James Bottomley , Bart Van Assche , Hannes Reinecke , Christoph Hellwig , Jim Gill , Cathy Avery , "Ewan D . Milne" , Brian King , James Smart , "Juergen E . Fischer" , Michael Schmitz , Finn Thain , Greg Kroah-Hartman , devel@driverdev.osuosl.org, linux-usb@vger.kernel.org, Dan Carpenter , Benjamin Block , Martin Schwidefsky , Heiko Carstens , linux-s390@vger.kernel.org References: <20190618013757.22401-1-ming.lei@redhat.com> <20190618013757.22401-11-ming.lei@redhat.com> From: Steffen Maier Date: Mon, 24 Jun 2019 17:13:24 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190618013757.22401-11-ming.lei@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19062415-0028-0000-0000-0000037D2117 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19062415-0029-0000-0000-0000243D3EE9 Message-Id: <95bfa1fb-d0eb-fc61-ecc0-001ae52a326f@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-24_10:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906240122 Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Hi Ming, On 6/18/19 3:37 AM, Ming Lei wrote: > Use the scatterlist iterators and remove direct indexing of the > scatterlist array. > > This way allows us to pre-allocate one small scatterlist, which can be > chained with one runtime allocated scatterlist if the pre-allocated one > isn't enough for the whole request. > > Cc: Steffen Maier > Cc: Benjamin Block > Cc: Martin Schwidefsky > Cc: Heiko Carstens > Cc: linux-s390@vger.kernel.org > Acked-by: Benjamin Block > Reviewed-by: Christoph Hellwig > Reviewed-by: Bart Van Assche > Signed-off-by: Ming Lei > --- > drivers/s390/scsi/zfcp_fc.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c > index 33eddb02ee30..b018b61bd168 100644 > --- a/drivers/s390/scsi/zfcp_fc.c > +++ b/drivers/s390/scsi/zfcp_fc.c > @@ -620,7 +620,7 @@ static void zfcp_fc_sg_free_table(struct scatterlist *sg, int count) > { > int i; > > - for (i = 0; i < count; i++, sg++) > + for (i = 0; i < count; i++, sg = sg_next(sg)) > if (sg) > free_page((unsigned long) sg_virt(sg)); > else > @@ -641,7 +641,7 @@ static int zfcp_fc_sg_setup_table(struct scatterlist *sg, int count) > int i; > > sg_init_table(sg, count); > - for (i = 0; i < count; i++, sg++) { > + for (i = 0; i < count; i++, sg = sg_next(sg)) { > addr = (void *) get_zeroed_page(GFP_KERNEL); > if (!addr) { > zfcp_fc_sg_free_table(sg, i); > I'm still catching up with emails that came during my vacation, so I'm not fully up-to-date on the current state of this and how to bring in potential fixups on top. I think, we also have two more (not so obvious) places in the corresponding response/completion code path, where we might need to introduce the proper iterator helper: zfcp_fsf.c: static int zfcp_fc_eval_gpn_ft(struct zfcp_fc_req *fc_req, struct zfcp_adapter *adapter, int max_entries) { struct scatterlist *sg = &fc_req->sg_rsp; ... /* first entry is the header */ for (x = 1; x < max_entries && !last; x++) { ... if (x % (ZFCP_FC_GPN_FT_ENT_PAGE + 1)) ... else acc = sg_virt(++sg); ^^^^ zfcp_dbf.c: static u16 zfcp_dbf_san_res_cap_len_if_gpn_ft(char *tag, struct zfcp_fsf_req *fsf, u16 len) { struct scatterlist *resp_entry = ct_els->resp; ... /* the basic CT_IU preamble is the same size as one entry in the GPN_FT * response, allowing us to skip special handling for it - just skip it */ for (x = 1; x < max_entries && !last; x++) { if (x % (ZFCP_FC_GPN_FT_ENT_PAGE + 1)) ... else acc = sg_virt(++resp_entry); ^^^^^^^^^^^^ What do you think? -- Mit freundlichen Gruessen / Kind regards Steffen Maier Linux on IBM Z Development https://www.ibm.com/privacy/us/en/ IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Matthias Hartmann Geschaeftsfuehrung: Dirk Wittkopp Sitz der Gesellschaft: Boeblingen Registergericht: Amtsgericht Stuttgart, HRB 243294