Zhou, > When a scsi_device is unpluged from scsi controller, if the > scsi_device is still be used by application layer,it won't be released > until users release it. In this case, scsi_device_remove just set the > scsi_device's state to be SDEV_DEL. But if you plug the disk just > before the old scsi_device is released, then there will be two > scsi_device structures in scsi_host->__devices. when the next > unpluging event happens,some low-level drivers will check whether the > scsi_device has been added to host (for example, the megaraid sas > series controller) by calling scsi_device_lookup(call > __scsi_device_lookup) in function > megasas_aen_polling.__scsi_device_lookup will return the first > scsi_device. Because its state is SDEV_DEL, the scsi_device_lookup > will return NULL finally, making the low-level driver assume that the > scsi_device has been removed,and won't call scsi_device_remove,which > will lead the failure of hot swap.
Applied to 4.12/scsi-fixes. Thank you! -- Martin K. Petersen Oracle Linux Engineering
