On Thu, Jun 30, 2011 at 11:28:27PM +0000, KY Srinivasan wrote: > > On Wed, Jun 29, 2011 at 07:38:21AM -0700, K. Y. Srinivasan wrote: > > > Further cleanup of the hv drivers: > > > > > > 1) Cleanup the reference counting mess for both stor and net devices. > > > > I really don't understand the need for reference counting on the storage > > side, especially now that you only have a SCSI driver. The SCSI > > midlayer does proper counting on it's objects (Scsi_Host, scsi_device, > > scsi_cmnd), so you'll get that for free given that SCSI drivers just > > piggyback on the midlayer lifetime rules. > > The reference counting allows us to properly deal with messages coming back from the host > to the guest with a racing remove of the device. I am told these messages could potentially be > not a response to a message sent from the guest. To deal with that the scsi subsystem has a two stage teardown for the SCSI host. First you call scsi_remove_host, at which point no new I/O to it can be started. After that you can wait for all outstanding messages, and finally you do a scsi_host_put to drop the long-term reference to it, and eventually free it. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
