On Tuesday, September 25, 2007 7:38 AM, Matthew Wilcox wrote: > As I said, it's ambitious. But it'll let us get rid of scsi_pointer > and host_scribble entirely. > Are you serious about removing the host_scribble? In fusion we currently are hanging our per request message frame pointer there. Its used for two reasons: (1) Old fibre channel firmware bug. The bug is the same message frame completed twice. 1st completion is okay and the scsi_cmd is reallocated to some other IO. Meanwhile the driver receives a double completion of the same message frame, and the driver attempts to complete the reallocated scsi_cmd to some other IO. The sanity check on host_scribble avoids this. (2) error recovery threads decides to complete a scsi_cmd before its been returned back by the scsi lld, and the scsi_cmd is reused for some other IO. Meanwhile fusion firmware finally decides it wants to command the command, then the driver is completing the reallocated scsi_cmd that is mapped to some other IO. Again, host_scribble sanity check makes sure we finish off the scsi_cmd that its intended for. Thus said, someone upgrades to newer FC firmware, they will not have issue #1. Regarding issue #2, if eh threads allow scsi lld to cleanup ts own scsi cmds, then we shouldn't need this. Eric - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
