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Return task management requests to queued execution, but differently.

Browse source 
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.
This commit is contained in:
Alexander Motin 2014-07-08 12:15:15 +00:00
parent aa75114c57
commit f5ffef352f
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=268391
1 changed files with 15 additions and 15 deletions
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30
sys/cam/ctl/ctl.c
View file

@ -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);