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 runtime 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 tracking the suspended state of a disk by introducing the
suspended boolean field in the scsi_disk structure. This flag is set to
true when the disk is suspended is sd_suspend_common() and resumed with
sd_resume(). When suspended is true, sd_shutdown() is not executed from
sd_remove().

Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>