bus_managers/scsi/queuing.cpp

7 	Part of Open SCSI bus manager
18 	HBAs as in this case the queuing is done by the SCSI bus manager
21 	Requests can be blocked by SIM or by the SCSI bus manager on a per-device
22 	or per-bus basis. There are three possible reasons:
25 	   - detected by bus manager automatically, or
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.
36 	SIM lock count and the bus manager lock count. The blocking test is in
39 	If a bus/device is blocked or has waiting requests/devices, new requests
42 	requeued request and autosense-requests, which are added first. Each bus
170 // add request to end of device queue and device to bus queue
201 // add request to begin of device queue and device to bus queue
215 		// make device first in bus queue to execute sense ASAP
231 // explictely unblock bus
232 static void scsi_unblock_bus_int( scsi_bus_info *bus, bool by_SIM )
238 	mutex_lock( &bus->mutex );
240 	was_servicable = scsi_can_service_bus( bus );
242 	scsi_unblock_bus_noresume( bus, by_SIM );
244 	start_retry = !was_servicable && scsi_can_service_bus( bus );
246 	mutex_unlock( &bus->mutex );
249 		release_sem( bus->start_service );
253 // explicitely unblock bus as requested by SIM
254 void scsi_unblock_bus( scsi_bus_info *bus )
256 	scsi_unblock_bus_int( bus, true );
263 	scsi_bus_info *bus = device->bus;
268 	mutex_lock( &bus->mutex );
270 	was_servicable = scsi_can_service_bus( bus );
274 	// add to bus queue if not locked explicitly anymore and requests are waiting
278 	start_retry = !was_servicable && scsi_can_service_bus( bus );
280 	mutex_unlock( &bus->mutex );
283 		release_sem( bus->start_service );
294 // SIM signals that it can handle further requests for this bus
295 void scsi_cont_send_bus( scsi_bus_info *bus )
301 	mutex_lock( &bus->mutex );
303 	was_servicable = scsi_can_service_bus( bus );
305 	scsi_clear_bus_overflow( bus );
307 	start_retry = !was_servicable && scsi_can_service_bus( bus );
309 	mutex_unlock( &bus->mutex );
312 		release_sem_etc( bus->start_service, 1, 0/*B_DO_NOT_RESCHEDULE*/ );
319 	scsi_bus_info *bus = device->bus;
324 	mutex_lock( &bus->mutex );
326 	was_servicable = scsi_can_service_bus( bus );
332 		// add to bus queue if not locked explicitly anymore and requests are waiting
337 	// no device overflow implicits no bus overflow
339 	scsi_clear_bus_overflow( bus );
341 	start_retry = !was_servicable && scsi_can_service_bus( bus );
343 	mutex_unlock( &bus->mutex );
348 		release_sem_etc( bus->start_service, 1, 0/*B_DO_NOT_RESCHEDULE*/ );
352 // explicitly block bus
353 static void scsi_block_bus_int( scsi_bus_info *bus, bool by_SIM )
357 	mutex_lock( &bus->mutex );
359 	scsi_block_bus_nolock( bus, by_SIM );
361 	mutex_unlock( &bus->mutex );
365 // explicitly block bus as requested by SIM
366 void scsi_block_bus( scsi_bus_info *bus )
368 	return scsi_block_bus_int( bus, true );
375 	scsi_bus_info *bus = device->bus;
379 	mutex_lock( &bus->mutex );
383 	// remove device from bus queue as it cannot be processed anymore
386 	mutex_unlock( &bus->mutex );