linux-kernel - Re: [PATCH RFC 2/2] scsi: ufshcd: Fix device links when BOOT WLUN fails to probe

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Date:   Wed, 7 Jul 2021 19:39:44 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     "Rafael J . Wysocki" <rafael@...nel.org>,
        Saravana Kannan <saravanak@...gle.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        "James E . J . Bottomley" <jejb@...ux.ibm.com>,
        linux-scsi@...r.kernel.org, Avri Altman <avri.altman@....com>,
        Bean Huo <huobean@...il.com>, Can Guo <cang@...eaurora.org>,
        Asutosh Das <asutoshd@...eaurora.org>,
        Bart Van Assche <bvanassche@....org>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC 2/2] scsi: ufshcd: Fix device links when BOOT WLUN
 fails to probe

On Wed, Jul 07, 2021 at 08:29:48PM +0300, Adrian Hunter wrote:
> If a LUN fails to probe (e.g. absent BOOT WLUN), the device will not have
> been registered but can still have a device link holding a reference to the
> device. The unwanted device link will prevent runtime suspend indefinitely,
> and cause some warnings if the supplier is ever deleted (e.g. by unbinding
> the UFS host controller). Fix by explicitly deleting the device link when
> SCSI destroys the SCSI device.
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>  drivers/scsi/ufs/ufshcd.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 708b3b62fc4d..483aa74fe2c8 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -5029,6 +5029,13 @@ static void ufshcd_slave_destroy(struct scsi_device *sdev)
>  		spin_lock_irqsave(hba->host->host_lock, flags);
>  		hba->sdev_ufs_device = NULL;
>  		spin_unlock_irqrestore(hba->host->host_lock, flags);
> +	} else {
> +		/*
> +		 * If a LUN fails to probe (e.g. absent BOOT WLUN), the device
> +		 * will not have been registered but can still have a device
> +		 * link holding a reference to the device.
> +		 */
> +		device_links_scrap(&sdev->sdev_gendev);

What created that link?  And why did it do that before probe happened
successfully?

thanks,

greg k-h