Re: Fwd: Waking up from resume locks up on sr device

[Bart Van Assche <bvanassche@acm.org>]

On 6/10/23 06:27, Bagas Sanjaya wrote:
> On 6/10/23 15:55, Pavel Machek wrote:
>>>> #regzbot introduced: v5.0..v6.4-rc5 https://bugzilla.kernel.org/show_bug.cgi?id=217530
>>>> #regzbot title: Waking up from resume locks up on SCSI CD/DVD drive
>>>>
>>> The reporter had found the culprit (via bisection), so:
>>>
>>> #regzbot introduced: a19a93e4c6a98c
>> Maybe cc the authors of that commit?
> 
> Ah! I forgot to do that! Thanks anyway.

Hi Damien,

Why does the ATA code call scsi_rescan_device() before system resume has
finished? Would ATA devices still work with the patch below applied?

Thanks,

Bart.


diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 6a959c993dd8..be3971b7fd27 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1629,6 +1629,20 @@ void scsi_rescan_device(struct device *dev)
  {
  	struct scsi_device *sdev = to_scsi_device(dev);

+#ifdef CONFIG_PM_SLEEP
+	/*
+	 * The ATA subsystem may call scsi_rescan_device() before resuming has
+	 * finished. If this happens, prevent a deadlock on the device_lock()
+	 * call by skipping rescanning.
+	 */
+	if (dev->power.is_suspended)
+		return;
+#endif
+
+	/*
+	 * Serialize scsi_driver.rescan() calls and scsi_driver.gendrv.remove()
+	 * calls.
+	 */
  	device_lock(dev);

  	scsi_attach_vpd(sdev);