On Tue, 2019-04-09 at 10:44 -0400, Alan Stern wrote: > On Mon, 8 Apr 2019, Martin K. Petersen wrote: > > > > > Alan, > > > > > So it looks as though the SCSI subsystem doesn't like to have a reset > > > handler call scsi_remove_host. > > > > Are you talking about a PCI device removal handler or a SCSI error > > handler? > > The context of this discussion is a USB mass-storage device where the > device's port on its upstream hub has been powered off. The > powered-off port causes an executing command to time out. As a result > the SCSI error handler runs and calls the USB reset routine, but the > reset fails because the kernel is unable to communicate with the device > through the powered-off port. This causes the USB reset routine to > unbind the device from its USB driver, which in turn calls > scsi_remove_host -- while the error handler is still running.
>From which context does that unbind happen? From inside a SCSI EH callback or from the context of a workqueue? I think the former is not allowed but that the latter is allowed. The SRP initiator driver (ib_srp.c) follows the latter approach. See also srp_queue_remove_work(). Bart.
