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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 0A24AC433DB for ; Sat, 20 Mar 2021 12:18:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CED7461975 for ; Sat, 20 Mar 2021 12:18:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229732AbhCTMRb (ORCPT ); Sat, 20 Mar 2021 08:17:31 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:2722 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229793AbhCTMRH (ORCPT ); Sat, 20 Mar 2021 08:17:07 -0400 Received: from fraeml713-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4F2flZ10yKz67yxJ; Sat, 20 Mar 2021 20:12:26 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml713-chm.china.huawei.com (10.206.15.32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Sat, 20 Mar 2021 13:17:05 +0100 Received: from [10.210.166.185] (10.210.166.185) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Sat, 20 Mar 2021 12:17:03 +0000 Subject: Re: [PATCH v2] scsi: libsas: Reset num_scatter if libata mark qc as NODATA To: Jason Yan , Jolly Shah , , , , , , CC: , References: <20210318225632.2481291-1-jollys@google.com> <5e7ea537-86ab-f654-1df4-765364116e18@huawei.com> From: John Garry Message-ID: <993f97da-01f0-262b-3fbe-66fa1769698a@huawei.com> Date: Sat, 20 Mar 2021 12:14:52 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <5e7ea537-86ab-f654-1df4-765364116e18@huawei.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.210.166.185] X-ClientProxiedBy: lhreml735-chm.china.huawei.com (10.201.108.86) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/03/2021 01:43, Jason Yan wrote: > > > 在 2021/3/19 6:56, Jolly Shah 写道: >> When the cache_type for the scsi device is changed, the scsi layer >> issues a MODE_SELECT command. The caching mode details are communicated >> via a request buffer associated with the scsi command with data >> direction set as DMA_TO_DEVICE (scsi_mode_select). When this command >> reaches the libata layer, as a part of generic initial setup, libata >> layer sets up the scatterlist for the command using the scsi command >> (ata_scsi_qc_new). This command is then translated by the libata layer >> into ATA_CMD_SET_FEATURES (ata_scsi_mode_select_xlat). The libata layer >> treats this as a non data command (ata_mselect_caching), since it only >> needs an ata taskfile to pass the caching on/off information to the >> device. It does not need the scatterlist that has been setup, so it does >> not perform dma_map_sg on the scatterlist (ata_qc_issue). Unfortunately, >> when this command reaches the libsas layer(sas_ata_qc_issue), libsas >> layer sees it as a non data command with a scatterlist. It cannot >> extract the correct dma length, since the scatterlist has not been >> mapped with dma_map_sg for a DMA operation. When this partially >> constructed SAS task reaches pm80xx LLDD, it results in below warning. >> >> "pm80xx_chip_sata_req 6058: The sg list address >> start_addr=0x0000000000000000 data_len=0x0end_addr_high=0xffffffff >> end_addr_low=0xffffffff has crossed 4G boundary" >> >> This patch updates code to handle ata non data commands separately so >> num_scatter and total_xfer_len remain 0. >> >> Fixes: 53de092f47ff ("scsi: libsas: Set data_dir as DMA_NONE if libata >> marks qc as NODATA") >> Signed-off-by: Jolly Shah Reviewed-by: John Garry @luojiaxing, can you please test this? >> --- >> v2: >> - reorganized code to avoid setting num_scatter twice >> >>   drivers/scsi/libsas/sas_ata.c | 9 ++++----- >>   1 file changed, 4 insertions(+), 5 deletions(-) >> >> diff --git a/drivers/scsi/libsas/sas_ata.c >> b/drivers/scsi/libsas/sas_ata.c >> index 024e5a550759..8b9a39077dba 100644 >> --- a/drivers/scsi/libsas/sas_ata.c >> +++ b/drivers/scsi/libsas/sas_ata.c >> @@ -201,18 +201,17 @@ static unsigned int sas_ata_qc_issue(struct >> ata_queued_cmd *qc) >>           memcpy(task->ata_task.atapi_packet, qc->cdb, qc->dev->cdb_len); >>           task->total_xfer_len = qc->nbytes; >>           task->num_scatter = qc->n_elem; >> +        task->data_dir = qc->dma_dir; >> +    } else if (qc->tf.protocol == ATA_PROT_NODATA) { >> +        task->data_dir = DMA_NONE; > > Hi Jolly & John, > > We only set DMA_NONE for ATA_PROT_NODATA, I'm curious about why > ATA_PROT_NCQ_NODATA and ATAPI_PROT_NODATA do not need to set DMA_NONE? So we can see something like atapi_eh_tur() -> ata_exec_internal(), which is a ATAPI NONDATA and has DMA_NONE, so should be ok. Other cases, like those using the xlate function on the qc for ATA_PROT_NCQ_NODATA, could be checked further. For now, we're just trying to fix the fix. > > Thanks, > Jason > > >>       } else { >>           for_each_sg(qc->sg, sg, qc->n_elem, si) >>               xfer += sg_dma_len(sg); >>           task->total_xfer_len = xfer; >>           task->num_scatter = si; >> -    } >> - >> -    if (qc->tf.protocol == ATA_PROT_NODATA) >> -        task->data_dir = DMA_NONE; >> -    else >>           task->data_dir = qc->dma_dir; >> +    } >>       task->scatter = qc->sg; >>       task->ata_task.retry_count = 1; >>       task->task_state_flags = SAS_TASK_STATE_PENDING; >> > .