Re: [PATCH v4 09/23] scsi: sd: Do not issue commands to suspended disks on shutdown

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

On 9/20/23 06:54, Damien Le Moal wrote:
> If an error occurs when resuming a host adapter before the devices
> attached to the adapter are resumed, the adapter low level driver may
> remove the scsi host, resulting in a call to sd_remove() for the
> disks of the host. This in turn results in a call to sd_shutdown() which
> will issue a synchronize cache command and a start stop unit command to
> spindown the disk. sd_shutdown() issues the commands only if the device
> is not already suspended but does not check the power state for
> system-wide suspend/resume. That is, the commands may be issued with the
> device in a suspended state, which causes PM resume to hang, forcing a
> reset of the machine to recover.
> 
> Fix this by not calling sd_shutdown() in sd_remove() if the device
> is not running.

Hi Damien,

I'd like to look into an alternative fix (after this patch series went 
in) but I couldn't identify the call chain in the ATA resume code that 
results in removal of the SCSI host. Can you please show me the call 
chain that results in SCSI host removal if resuming fails?

Thanks,

Bart.