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 6C079C433E0 for ; Mon, 22 Mar 2021 08:41:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 227596196E for ; Mon, 22 Mar 2021 08:41:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229883AbhCVIko (ORCPT ); Mon, 22 Mar 2021 04:40:44 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:13655 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229547AbhCVIkm (ORCPT ); Mon, 22 Mar 2021 04:40:42 -0400 Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4F3nvM1KDtznV3M; Mon, 22 Mar 2021 16:38:07 +0800 (CST) Received: from [127.0.0.1] (10.40.192.131) by DGGEMS407-HUB.china.huawei.com (10.3.19.207) with Microsoft SMTP Server id 14.3.498.0; Mon, 22 Mar 2021 16:40:26 +0800 Subject: Re: [PATCH v2] scsi: libsas: Reset num_scatter if libata mark qc as NODATA To: John Garry , Jason Yan , "Jolly Shah" , , , , , CC: , References: <20210318225632.2481291-1-jollys@google.com> <5e7ea537-86ab-f654-1df4-765364116e18@huawei.com> <993f97da-01f0-262b-3fbe-66fa1769698a@huawei.com> From: luojiaxing Message-ID: Date: Mon, 22 Mar 2021 16:40:26 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <993f97da-01f0-262b-3fbe-66fa1769698a@huawei.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.40.192.131] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/3/20 20:14, John Garry wrote: > 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? Sure, let me take a look, and reply the test result here later Thanks Jiaxing > >>> --- >>> 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; >>> >> . > > > . >