From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3B762EEA9; Thu, 27 Mar 2025 21:45:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.168.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743111945; cv=none; b=EuiXy35PaH8bFy9coWva7qNa9WpTAQGBaY1XBaKFv/VlRWhBszVQsbRWt+ap8UWdukeSai1rAPsJV/bmLzFopxduOXN1dxCelACVe5QkiKqu4SwK5oJB7pFT8ng6tZrOWKNbek/PSu6of4DPzQXDdHZvhD/6XWkM/Oami6fp8gc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743111945; c=relaxed/simple; bh=wt/bKye6ykh5HMh8CV7ujLnDR75xCH9uZa9b0I+dfYc=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=hc0f1Tne5OY+aWQ4C4Tjr4dwC0NCzmPGY/K9LVeRrPQXrHteSkr1Awxnyes8Fy71WMBgbYO7AQ/qRjt8/BNfawXIy0A/4iaQl9/fbXq7GlomZU8hiRyS3wnLXU/DxwiNVPmsiyMS0wnl+PguQq35ds7qT5sQh9rhVphNMXbvtwE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=quicinc.com; spf=pass smtp.mailfrom=quicinc.com; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b=Qgw/8Fey; arc=none smtp.client-ip=205.220.168.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=quicinc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=quicinc.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b="Qgw/8Fey" Received: from pps.filterd (m0279865.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 52RFOsjC005967; Thu, 27 Mar 2025 21:45:12 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=qcppdkim1; bh= zvANn6MKGnI/R3dATeqeGh0E6qIlFeBO/SDqOqZXNB4=; b=Qgw/8FeyzSmI1wlB NfZnvKcBcpSNZt7B94o8k/ebxojfA/8usORWpJsGNHzNzeM05YvqRUdCY7Kp2ARz g3fc0X28lGyHiUt4Yh0AuPYfjg8wJS+JTjwsS8/9lOAAVj3ah1MOqbKn9aQ0xXYf JcmqcrUN+LNykHIbvC7sHloXfD2NAMZjyy724owaUuVTc71Bmz8nOvaM1Pow2Vi+ a6osk9abCncVB2QbmfN7bdF/lZU+k3du3um/I9gBiEhNVXwS7nofdz67m+Jy+loM +kWaO+IgkFOWEo+lIyjtB4TefMz6Of8q9nQcFmLOhTx60gfG7f9QjvDcmsYq115r Ns/Xhw== Received: from nasanppmta03.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 45m7nf6pfh-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 27 Mar 2025 21:45:11 +0000 (GMT) Received: from nasanex01a.na.qualcomm.com (nasanex01a.na.qualcomm.com [10.52.223.231]) by NASANPPMTA03.qualcomm.com (8.18.1.2/8.18.1.2) with ESMTPS id 52RLjA95029897 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 27 Mar 2025 21:45:10 GMT Received: from [10.46.162.103] (10.80.80.8) by nasanex01a.na.qualcomm.com (10.52.223.231) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Thu, 27 Mar 2025 14:45:10 -0700 Message-ID: <4cb20c80-9bb0-e147-e3c0-467f4c8828ba@quicinc.com> Date: Thu, 27 Mar 2025 14:45:10 -0700 Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [PATCH v4 1/1] scsi: ufs: core: add device level exception support Content-Language: en-US To: Bart Van Assche , Arthur Simchaev , "quic_cang@quicinc.com" , "quic_nitirawa@quicinc.com" , "avri.altman@wdc.com" , "peter.wang@mediatek.com" , "manivannan.sadhasivam@linaro.org" , "minwoo.im@samsung.com" , "adrian.hunter@intel.com" , "martin.petersen@oracle.com" CC: "linux-scsi@vger.kernel.org" , Alim Akhtar , "James E.J. Bottomley" , Matthias Brugger , AngeloGioacchino Del Regno , Bean Huo , Keoseong Park , Ziqi Chen , Al Viro , "Gwendal Grignou" , Eric Biggers , open list , "moderated list:ARM/Mediatek SoC support:Keyword:mediatek" , "moderated list:ARM/Mediatek SoC support:Keyword:mediatek" References: <4370b3a3b5a5675bb3e75aaa48a273674c159339.1742526978.git.quic_nguyenb@quicinc.com> <0a68d437-5d6a-42aa-ae4e-6f5d89cfcaf3@acm.org> <3d7b543c-1165-42e0-8471-25b04c7572ac@acm.org> From: "Bao D. Nguyen" In-Reply-To: <3d7b543c-1165-42e0-8471-25b04c7572ac@acm.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nasanex01a.na.qualcomm.com (10.52.223.231) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-ORIG-GUID: nCKyFslt_4G4_-qPtbD5MfnbT8RKH2fg X-Proofpoint-GUID: nCKyFslt_4G4_-qPtbD5MfnbT8RKH2fg X-Authority-Analysis: v=2.4 cv=IMMCChvG c=1 sm=1 tr=0 ts=67e5c6e7 cx=c_pps a=JYp8KDb2vCoCEuGobkYCKw==:117 a=JYp8KDb2vCoCEuGobkYCKw==:17 a=GEpy-HfZoHoA:10 a=IkcTkHD0fZMA:10 a=Vs1iUdzkB0EA:10 a=St5hpErUO6hIVgotEGUA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1095,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-03-27_04,2025-03-27_02,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 impostorscore=0 malwarescore=0 mlxscore=0 clxscore=1015 phishscore=0 priorityscore=1501 mlxlogscore=999 adultscore=0 lowpriorityscore=0 bulkscore=0 spamscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2503270146 On 3/27/2025 4:36 AM, Bart Van Assche wrote: > On 3/26/25 7:47 PM, Bao D. Nguyen wrote: >> On 3/26/2025 3:49 AM, Bart Van Assche wrote: >>> On 3/25/25 6:15 PM, Bao D. Nguyen wrote: >>>> The existing "struct utp_upiu_query_v4_0" probably has a bug in it. >>>> It does not use the  __attribute__((__packed__)) attribute. The >>>> compiler is free to add padding in this structure, resulting in the >>>> read attribute value being incorrect. I plan to provide a separate >>>> patch to fix this issue. >>> >>> Adding __attribute__((__packed__)) or __packed to data structures that >>> don't need it is not an improvement but is a change that makes >>> processing slower on architectures that do not support unaligned >>> accesses. Instead of adding __packed to data structures in their >>> entirety, only add it to those members that need it and check the >>> structure size as follows: >>> >>> static_assert(sizeof(...) == ...); >>> >> Thank you for the info on this, Bart. >> IMO, this response upiu data should be __packed because the data >> coming from the hardware follows a strict format as defined by the >> spec. If we support __pack each individual field which data may be >> read by the driver (the attribute read commands) and check the >> validity of their sizes, it may add some complexity? > > Hi Bao, > > As explained in my previous email, adding __packed to data structures in > their entirety is a bad practice. Please don't do this. > > Regarding your question: I have not yet seen any data structure that > represents an on-the-wire data format where every single data member > has to be annotated with __packed. Only data members that are not > aligned to a natural boundary need this annotation. Examples are > available in this header file: include/scsi/srp.h. > Thanks Bart. How about we change the current utp_upiu_query_v4_0 to struct utp_upiu_query_v4_0 { __u8 opcode; __u8 idn; __u8 index; __u8 selector; __u8 cmd_specifics[8]; /* private: */ __be32 reserved; }; Depending on the opcode/transaction, the cmd_specifics[] can be type casted to access the LENGTH, FLAG_VALUE, VALUE[0:63] fields of the QUERY UPIU. The __u8 array[8] would also prevent the compiler padding to the data. Thanks, Bao