linux-kernel - Re: [PATCH v5 00/11] scsi: ufs: Remove overzealous memory barriers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date: Mon,  8 Apr 2024 23:08:50 -0400
From: "Martin K. Petersen" <martin.petersen@...cle.com>
To: Andy Gross <agross@...nel.org>, Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Manivannan Sadhasivam <mani@...nel.org>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Hannes Reinecke <hare@...e.de>, Janek Kotas <jank@...ence.com>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        Bart Van Assche <bvanassche@....org>, Can Guo <quic_cang@...cinc.com>,
        Anjana Hari <quic_ahari@...cinc.com>,
        Andrew Halaney <ahalaney@...hat.com>
Cc: "Martin K . Petersen" <martin.petersen@...cle.com>,
        Will Deacon <will@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: Re: [PATCH v5 00/11] scsi: ufs: Remove overzealous memory barriers

On Fri, 29 Mar 2024 15:46:42 -0500, Andrew Halaney wrote:

> Please review with care as I'm not all that confident in this subject.
> UFS has a lot of mb() variants used, most with comments saying "ensure this
> takes effect before continuing". mb()'s aren't really the way to
> guarantee that, a read back is the best method.
> 
> Some of these though I think could go a step further and remove the mb()
> variant without a read back. As far as I can tell there's no real reason
> to ensure it takes effect in most cases (there's no delay() or anything
> afterwards, and eventually another readl()/writel() happens which is by
> definition ordered). Some of the patches in this series do that if I was
> confident it was safe (or a reviewer pointed out prior that they thought
> it was safe to do so).
> 
> [...]

Applied to 6.10/scsi-queue, thanks!

[01/11] scsi: ufs: qcom: Perform read back after writing reset bit
        https://git.kernel.org/mkp/scsi/c/c4d28e06b0c9
[02/11] scsi: ufs: qcom: Perform read back after writing REG_UFS_SYS1CLK_1US
        https://git.kernel.org/mkp/scsi/c/a862fafa263a
[03/11] scsi: ufs: qcom: Remove unnecessary mb() after writing testbus config
        https://git.kernel.org/mkp/scsi/c/95d26dda90df
[04/11] scsi: ufs: qcom: Perform read back after writing unipro mode
        https://git.kernel.org/mkp/scsi/c/823150ecf04f
[05/11] scsi: ufs: qcom: Perform read back after writing CGC enable
        https://git.kernel.org/mkp/scsi/c/d9488511b3ac
[06/11] scsi: ufs: cdns-pltfrm: Perform read back after writing HCLKDIV
        https://git.kernel.org/mkp/scsi/c/b715c55daf59
[07/11] scsi: ufs: core: Perform read back after writing UTP_TASK_REQ_LIST_BASE_H
        https://git.kernel.org/mkp/scsi/c/408e28086f1c
[08/11] scsi: ufs: core: Perform read back after disabling interrupts
        https://git.kernel.org/mkp/scsi/c/e4a628877119
[09/11] scsi: ufs: core: Perform read back after disabling UIC_COMMAND_COMPL
        https://git.kernel.org/mkp/scsi/c/4bf3855497b6
[10/11] scsi: ufs: core: Remove unnecessary wmb() after ringing doorbell
        https://git.kernel.org/mkp/scsi/c/d3fb9a24a602
[11/11] scsi: ufs: core: Remove unnecessary wmb() prior to writing run/stop regs
        https://git.kernel.org/mkp/scsi/c/356a8ce7cd50

-- 
Martin K. Petersen	Oracle Linux Engineering