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From: Adrian Hunter <adrian.hunter@intel.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J . Wysocki" <rafael@kernel.org>,
	Saravana Kannan <saravanak@google.com>,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	"James E . J . Bottomley" <jejb@linux.ibm.com>,
	linux-scsi@vger.kernel.org, Avri Altman <avri.altman@wdc.com>,
	Bean Huo <huobean@gmail.com>, Can Guo <cang@codeaurora.org>,
	Asutosh Das <asutoshd@codeaurora.org>,
	Bart Van Assche <bvanassche@acm.org>,
	linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC 2/2] scsi: ufshcd: Fix device links when BOOT WLUN fails to probe
Date: Wed, 7 Jul 2021 20:49:58 +0300	[thread overview]
Message-ID: <66130101-b0c5-a9a3-318a-468c6f3b380f@intel.com> (raw)
In-Reply-To: <YOXm4FuL/CW4lYDZ@kroah.com>

On 7/07/21 8:39 pm, Greg Kroah-Hartman wrote:
> 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@intel.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?

The same driver created the link.

The documentation seems to say it is allowed to, if it is the consumer.
From Documentation/driver-api/device_link.rst

  Usage
  =====

  The earliest point in time when device links can be added is after
  :c:func:`device_add()` has been called for the supplier and
  :c:func:`device_initialize()` has been called for the consumer.





  reply	other threads:[~2021-07-07 17:49 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-07 17:29 [PATCH RFC 0/2] driver core: Add ability to delete device links of unregistered devices Adrian Hunter
2021-07-07 17:29 ` [PATCH RFC 1/2] " Adrian Hunter
2021-07-07 17:38   ` Greg Kroah-Hartman
2021-07-07 17:29 ` [PATCH RFC 2/2] scsi: ufshcd: Fix device links when BOOT WLUN fails to probe Adrian Hunter
2021-07-07 17:39   ` Greg Kroah-Hartman
2021-07-07 17:49     ` Adrian Hunter [this message]
2021-07-08 12:31       ` Rafael J. Wysocki
2021-07-08 14:17         ` Adrian Hunter
2021-07-08 15:03           ` Rafael J. Wysocki
2021-07-08 15:12             ` Rafael J. Wysocki
2021-07-08 16:02               ` Adrian Hunter
2021-07-08 16:45           ` Saravana Kannan
2021-07-08 16:48             ` Rafael J. Wysocki
2021-07-08 16:57               ` Saravana Kannan
2021-07-08 17:39                 ` Rafael J. Wysocki
2021-07-07 17:40 ` [PATCH RFC 0/2] driver core: Add ability to delete device links of unregistered devices Greg Kroah-Hartman
2021-07-07 17:41   ` Saravana Kannan

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