svn commit: r268391 - head/sys/cam/ctl

[Alexander Motin]

Author: mav
Date: Tue Jul  8 12:15:15 2014
New Revision: 268391
URL: http://svnweb.freebsd.org/changeset/base/268391

Log:
  Return task management requests to queued execution, but differently.
  
  Testing shown that both original queued design with separate task queue,
  and recent direct execution design had significant flaw: If abort request
  arrives just after the victim, the last one may not be in the ooa_queue
  yet, and so invisible for the task management function.
  
  Unlike original queued implementation, use same queue for all SCSI and
  TASK requests from the same initiator. That avoids races between them:
  task functions are always executed in proper time, relatively to other
  requests.

Modified:
  head/sys/cam/ctl/ctl.c

Modified: head/sys/cam/ctl/ctl.c
==============================================================================
--- head/sys/cam/ctl/ctl.c	Tue Jul  8 10:11:47 2014	(r268390)
+++ head/sys/cam/ctl/ctl.c	Tue Jul  8 12:15:15 2014	(r268391)
@@ -12066,10 +12066,6 @@ ctl_abort_task(union ctl_io *io)
 	return (0);
 }
 
-/*
- * This routine cannot block!  It must be callable from an interrupt
- * handler as well as from the work thread.
- */
 static void
 ctl_run_task(union ctl_io *io)
 {
@@ -13690,10 +13686,8 @@ ctl_queue(union ctl_io *io)
 
 	switch (io->io_hdr.io_type) {
 	case CTL_IO_SCSI:
-		ctl_enqueue_incoming(io);
-		break;
 	case CTL_IO_TASK:
-		ctl_run_task(io);
+		ctl_enqueue_incoming(io);
 		break;
 	default:
 		printf("ctl_queue: unknown I/O type %d\n", io->io_hdr.io_type);
@@ -13862,6 +13856,16 @@ ctl_work_thread(void *arg)
 			retval = ctl_process_done(io);
 			continue;
 		}
+		io = (union ctl_io *)STAILQ_FIRST(&thr->incoming_queue);
+		if (io != NULL) {
+			STAILQ_REMOVE_HEAD(&thr->incoming_queue, links);
+			mtx_unlock(&thr->queue_lock);
+			if (io->io_hdr.io_type == CTL_IO_TASK)
+				ctl_run_task(io);
+			else
+				ctl_scsiio_precheck(softc, &io->scsiio);
+			continue;
+		}
 		if (!ctl_pause_rtr) {
 			io = (union ctl_io *)STAILQ_FIRST(&thr->rtr_queue);
 			if (io != NULL) {
@@ -13873,13 +13877,6 @@ ctl_work_thread(void *arg)
 				continue;
 			}
 		}
-		io = (union ctl_io *)STAILQ_FIRST(&thr->incoming_queue);
-		if (io != NULL) {
-			STAILQ_REMOVE_HEAD(&thr->incoming_queue, links);
-			mtx_unlock(&thr->queue_lock);
-			ctl_scsiio_precheck(softc, &io->scsiio);
-			continue;
-		}
 
 		/* Sleep until we have something to do. */
 		mtx_sleep(thr, &thr->queue_lock, PDROP | PRIBIO, "-", 0);
@@ -13917,8 +13914,11 @@ ctl_enqueue_incoming(union ctl_io *io)
 {
 	struct ctl_softc *softc = control_softc;
 	struct ctl_thread *thr;
+	u_int idx;
 
-	thr = &softc->threads[io->io_hdr.nexus.targ_mapped_lun % worker_threads];
+	idx = (io->io_hdr.nexus.targ_port * 127 +
+	       io->io_hdr.nexus.initid.id) % worker_threads;
+	thr = &softc->threads[idx];
 	mtx_lock(&thr->queue_lock);
 	STAILQ_INSERT_TAIL(&thr->incoming_queue, &io->io_hdr, links);
 	mtx_unlock(&thr->queue_lock);