bus_managers/scsi/queuing.cpp

9 	Queuing of SCSI request
11 	Some words about queuing, i.e. making sure that no request
26 	   - detected by SIM which calls "requeue" for affected request
32 	The first condition is automatically cleared when a request has
40 	are added to a device-specific request queue in an elevator-sort style,
42 	requeued request and autosense-requests, which are added first. Each bus
52 // add request to device queue, using evelvator sort
64 		SHOW_FLOW0( 1, "no other queued request" );
74 		SHOW_FLOW0( 1, "adding synced request to tail" );
80 		SHOW_FLOW0( 1, "adding unsortable request to tail" );
86 	// - sort request accendingly according to head position
95 	// - if position of request to be inserted is between current
96 	//   (i.e. last) position and position of first queued request,
98 	// - if position of first queued request is before current position
99 	//   and position of new req is before first queued request, add it
101 	//   request are sorted monotically increasing
116 		// we should have a new first request, make sure we don't bypass syncs
124 			SHOW_FLOW0( 1, "scheduled request in front of all other reqs of device" );
128 			SHOW_FLOW0( 1, "req would bypass ordered request" );
131 	// the insertion sort loop ignores ordered flag of last request,
134 		SHOW_FLOW0( 1, "last entry is ordered, adding new request as last" );
150 	// if we bumped into ordered request, append new request at tail
152 		SHOW_FLOW0( 1, "overtaking ordered request in sorting - adding as last" );
161 	// new request as last because request list is circular;
162 	// don't check whether we added request as first as this is impossible
170 // add request to end of device queue and device to bus queue
172 void scsi_add_queued_request( scsi_ccb *request )
174 	scsi_device_info *device = request->device;
178 	request->state = SCSI_STATE_QUEUED;
179 	scsi_insert_new_request( device, request );
185 			request->sort );
201 // add request to begin of device queue and device to bus queue
202 // used only for auto-sense request
203 void scsi_add_queued_request_first( scsi_ccb *request )
205 	scsi_device_info *device = request->device;
209 	request->state = SCSI_STATE_QUEUED;
210 	scsi_add_req_queue_first( request );
222 void scsi_remove_queued_request( scsi_ccb *request )
224 	scsi_remove_req_queue( request );
226 	if( request->device->queued_reqs == NULL )
227 		scsi_remove_device_queue( request->device );