From f5ffef352f96ca01470dab3ceac05e4fa5bf6504 Mon Sep 17 00:00:00 2001
From: Alexander Motin <mav@FreeBSD.org>
Date: Tue, 8 Jul 2014 12:15:15 +0000
Subject: [PATCH] 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.
---
 sys/cam/ctl/ctl.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/sys/cam/ctl/ctl.c b/sys/cam/ctl/ctl.c
index c4f345fa36c..f7d5e41d33f 100644
--- a/sys/cam/ctl/ctl.c
+++ b/sys/cam/ctl/ctl.c
@@ -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);