Hi, I'm adding code to enable the hv_storvsc driver (drivers/scsi/storvsc_drv.c) for hibernation (ACPI S5). I know how to save/restore the state of the virtual Hyper-V SCSI adapter, but I don't know how to prevent the higher layer SCSI driver(s) from submitting new I/O requests to the low level driver hv_storvsc, before I disable the Hyper-V SCSI adapter in hv_storvsc. Note: I can not call scsi_remove_host(), because the SCSI host should not disappear and re-appear on hibernation. scsi_target_block() calls scsi_internal_device_block() -> blk_mq_quiesce_queue(), but it is only used in a few drivers (scsi_transport_fc.c, scsi_transport_iscsi.c and scsi_transport_srp.c), so I doubt it is suitable to me? scsi_block_requests() is used in a lot of drivers and hence is more likely to be the API I'm looking for, but it only sets a flag shost->host_self_blocked -- how can this prevent another CPU from submitting I/O requests? I also checked scsi_bus_pm_ops, but it's only for "sdev": see scsi_bus_suspend_common() -> "if (scsi_is_sdev_device(dev))...". Even for "sdev", it looks the scsi_dev_type_suspend() can't work for me, because it looks the sdev's driver is sd, whose sd_pm_ops doesn't define the .freeze and .thaw ops, which are needed in hibernation. sd_pm_ops does define .suspend and .resume, but it looks they are only for suspend-to-memory (ACPI S3). Can you please recommend the standard way to prevent the higher layer SCSI driver(s) from submitting new I/O requests? How do the other low level SCSI adapter drivers support hibernation? I checked some PCI HBA drivers, and they use scsi_block_requests(), but as I described above, I don't know how setting a flag can prevent another CPU from submitting I/O requests. Looking forward to your insights! Thanks! --Dexuan
