Received-SPF: pass (google.com: domain of linux-kernel+bounces-76772-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Message-ID: <f5ac9637-99e2-487a-998c-5e63fdd3ccff@acm.org>
Date: Thu, 22 Feb 2024 07:25:57 -0800
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH] scsi: ufs: core: Fix setup_xfer_req invocation
Content-Language: en-US
To: Rohit Ner <rohitner@google.com>, Can Guo <quic_cang@quicinc.com>
Cc: Bean Huo <beanhuo@micron.com>, Stanley Chu <stanley.chu@mediatek.com>,
 "Martin K. Petersen" <martin.petersen@oracle.com>,
 Jaegeuk Kim <jaegeuk@kernel.org>, Avri Altman <avri.altman@wdc.com>,
 linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20240220090805.2886914-1-rohitner@google.com>
 <1920a2f6-e398-47af-a5d7-9dad9c70e03d@acm.org>
 <c7635c10-1724-4db5-9568-d554e1c64f72@quicinc.com>
 <CAGt9f=T5352bo=K2OAa7QRMds=tQC1JspN+zQ2aYxNRDWGSVnA@mail.gmail.com>
From: Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <CAGt9f=T5352bo=K2OAa7QRMds=tQC1JspN+zQ2aYxNRDWGSVnA@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit

On 2/22/24 00:27, Rohit Ner wrote:
> Can we stick to the current approach of moving the .setup_xfer_req()
> up, keeping in mind the following pros?
> 1. Avoid redundant callbacks for setting up transfers
> 2. Trim the duration for which hba->outstanding_lock is acquired unnecessarily

No, we can't. The Exynos implementation of the .setup_xfer_req() callback
is not thread-safe and relies on serialization by the caller. This patch
breaks the Exynos driver. A better title for this patch would be "Break
the setup_xfer_req() invocation".

Bart.