bus_managers/scsi/queuing.cpp

21 	Requests can be blocked by SIM or by the SCSI bus manager on a per-device
27 	2. SIM blocks bus/device explictely
28 	3. bus manager blocks bus/device explictly (currently used for
30 	4. the device has queued requests or the bus has waiting devices resp.
34 	third cases, the SIM/bus manager must explictely unblock the bus/device.
39 	If a bus/device is blocked or has waiting requests/devices, new requests
40 	are added to a device-specific request queue in an elevator-sort style,
44 	device is to be added to this queue, it is always appended at tail
52 // add request to device queue, using evelvator sort
53 static void scsi_insert_new_request( scsi_device_info *device,
61 	first = device->queued_reqs;
70 		first, first->sort, device->last_sort );
108 	if( (device->last_sort <= new_request->sort &&
110 		(first->sort < device->last_sort &&
114 		SHOW_FLOW0( 3, "trying to insert req at head of device req queue" );
124 			SHOW_FLOW0( 1, "scheduled request in front of all other reqs of device" );
170 // add request to end of device queue and device to bus queue
174 	scsi_device_info *device = request->device;
179 	scsi_insert_new_request( device, request );
182 		scsi_ccb *tmp = device->queued_reqs;
184 		dprintf( "pos=%lld, to_insert=%lld; ", device->last_sort,
188 			dprintf( "%lld, %s", tmp->sort, tmp->next == device->queued_reqs ? "\n" : "" );
190 		} while( tmp != device->queued_reqs );
193 	// if device is not deliberately locked, mark it as waiting
194 	if( device->lock_count == 0 ) {
195 		SHOW_FLOW0( 3, "mark device as waiting" );
196 		scsi_add_device_queue_last( device );
201 // add request to begin of device queue and device to bus queue
205 	scsi_device_info *device = request->device;
212 	// if device is not deliberately locked, mark it as waiting
213 	if( device->lock_count == 0 ) {
214 		SHOW_FLOW0( 3, "mark device as waiting" );
215 		// make device first in bus queue to execute sense ASAP
216 		scsi_add_device_queue_first( device );
221 // remove requests from queue, removing device from queue if idle
226 	if( request->device->queued_reqs == NULL )
227 		scsi_remove_device_queue( request->device );
260 // explicitly unblock device
261 static void scsi_unblock_device_int( scsi_device_info *device, bool by_SIM )
263 	scsi_bus_info *bus = device->bus;
272 	scsi_unblock_device_noresume( device, by_SIM );
275 	if( device->lock_count == 0 && device->queued_reqs != NULL )
276 		scsi_add_device_queue_last( device );
287 // explicitely unblock device as requested by SIM
288 void scsi_unblock_device( scsi_device_info *device )
290 	return scsi_unblock_device_int( device, true );
316 // SIM signals that it can handle further requests for this device
317 void scsi_cont_send_device( scsi_device_info *device )
319 	scsi_bus_info *bus = device->bus;
328 	if( device->sim_overflow ) {
329 		device->sim_overflow = false;
330 		--device->lock_count;
333 		if( device->lock_count == 0 && device->queued_reqs != NULL )
334 			scsi_add_device_queue_last( device );
337 	// no device overflow implicits no bus overflow
372 // explicitly block device
373 static void scsi_block_device_int( scsi_device_info *device, bool by_SIM )
375 	scsi_bus_info *bus = device->bus;
381 	scsi_block_device_nolock( device, by_SIM );
383 	// remove device from bus queue as it cannot be processed anymore
384 	scsi_remove_device_queue( device );
390 // explicitly block device as requested by SIM
391 void scsi_block_device( scsi_device_info *device )
393 	return scsi_block_device_int( device, true );