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From: Can Guo <cang@codeaurora.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: asutoshd@codeaurora.org, nguyenb@codeaurora.org,
	hongwus@codeaurora.org, ziqichen@codeaurora.org,
	linux-scsi@vger.kernel.org, kernel-team@android.com,
	Alim Akhtar <alim.akhtar@samsung.com>,
	Avri Altman <avri.altman@wdc.com>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Stanley Chu <stanley.chu@mediatek.com>,
	Bean Huo <beanhuo@micron.com>, Jaegeuk Kim <jaegeuk@kernel.org>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 5/6] scsi: ufs: Let host_sem cover the entire system suspend/resume
Date: Mon, 17 May 2021 11:22:27 +0800	[thread overview]
Message-ID: <98a7135ef1ce34e23e84817cf6167e1a@codeaurora.org> (raw)
In-Reply-To: <b59e0cd4-d560-6724-3f30-a5232dd41a8f@acm.org>

Hi Bart,

On 2021-05-14 11:55, Bart Van Assche wrote:
> 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 for the comments. These contexts are changing critical data and
registers, so the sem is used to protect data actually, just like the
scaling_lock protecting scaling and cmd transations.

Thanks,

Can Guo.

> 
> Thanks,
> 
> Bart.

  reply	other threads:[~2021-05-17  3:22 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-13  5:55 [PATCH v1 0/6] Complementary changes for error handling Can Guo
2021-05-13  5:55 ` [PATCH v1 1/6] scsi: ufs: Differentiate status between hba pm ops and wl pm ops Can Guo
2021-05-13  5:55 ` [PATCH v1 1/6] scsi: ufs: Differentiate status of hba " Can Guo
2021-05-13  5:58   ` Can Guo
2021-05-13  5:55 ` [PATCH v1 2/6] scsi: ufs: Update the return value of supplier " Can Guo
2021-05-13  5:55 ` [PATCH v1 3/6] scsi: ufs: Simplify error handling preparation Can Guo
2021-05-13  5:55 ` [PATCH v1 4/6] scsi: ufs: Update ufshcd_recover_pm_error() Can Guo
2021-05-13  5:55 ` [PATCH v1 5/6] scsi: ufs: Let host_sem cover the entire system suspend/resume Can Guo
2021-05-14  3:55   ` Bart Van Assche
2021-05-17  3:22     ` Can Guo [this message]
2021-05-17 15:05       ` Bart Van Assche
2021-05-13  5:55 ` [PATCH v1 6/6] scsi: ufs: Update the fast abort path in ufshcd_abort() for PM requests Can Guo
2021-05-14  4:05   ` Bart Van Assche
2021-05-14  4:17     ` Can Guo

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