On Wed, Apr 19, 2023 at 01:41:12PM +0800, Kai-Heng Feng wrote:
> During system resume, if an EH is schduled after ATA host is resumed
> (i.e. ATA_PFLAG_PM_PENDING cleared), but before the disk device is
> resumed, the device_lock hold by scsi_rescan_device() is never released
> so the dpm_resume() of the disk is blocked forerver.
>
> That's because scsi_attach_vpd() is expecting the disk device is in
> operational state, as it doesn't work on suspended device.
>
> To avoid such deadlock, avoid doing rescan if the disk is still
> suspended so the resume process of the disk device can proceed.
I'm no expert on suspend/resume, but wouldn't you then potentially miss
changes that have been done to the LUN during suspend?
What takes care of updating the VPDs, scsi-disk re-evaluation and such
in this case, when you block it initially during wakeup?
>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> ---
> drivers/scsi/scsi_scan.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index d217be323cc6..36680cb1535b 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -1621,6 +1621,9 @@ void scsi_rescan_device(struct device *dev)
> {
> struct scsi_device *sdev = to_scsi_device(dev);
>
> + if (dev->power.is_prepared)
> + return;
> +
> device_lock(dev);
>
> scsi_attach_vpd(sdev);
> --
> 2.34.1
>
--
Best Regards, Benjamin Block / Linux on IBM Z Kernel Development
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