linux-kernel - Re: [PATCH v1 5/6] scsi: ufs: Let host_sem cover the entire system suspend/resume

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Message-ID: <b59e0cd4-d560-6724-3f30-a5232dd41a8f@acm.org>
Date:   Thu, 13 May 2021 20:55:50 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Can Guo <cang@...eaurora.org>, asutoshd@...eaurora.org,
        nguyenb@...eaurora.org, hongwus@...eaurora.org,
        ziqichen@...eaurora.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com
Cc:     Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bean Huo <beanhuo@...ron.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 5/6] scsi: ufs: Let host_sem cover the entire system
 suspend/resume

On 5/12/21 10:55 PM, Can Guo wrote:
> UFS error handling now is doing more than just re-probing, but also sending
> scsi cmds, e.g., for clearing UACs, and recovering runtime PM error, which
> may change runtime status of scsi devices. To protect system suspend/resume
> from being disturbed by error handling, move the host_sem from wl pm ops
> to ufshcd_suspend_prepare() and ufshcd_resume_complete().

In ufshcd.h I found the following:

 * @host_sem: semaphore used to serialize concurrent contexts

That's the wrong way to use a synchronization object. A synchronization
object must protect data instead of code. Does host_sem perhaps need to
be split into multiple synchronization objects?

Thanks,

Bart.