[PATCH 2/2] scsi: register sysfs for scsi/iscsi workqueues

[Bob Liu]

This patch enable setting cpu affinity through "cpumask" for below
scsi/iscsi workqueues, so as to get better isolation.
- scsi_wq_*
- scsi_tmf_*
- iscsi_q_xx
- iscsi_eh

Signed-off-by: Bob Liu <bob...@oracle.com>
---
drivers/scsi/hosts.c | 4 ++--
drivers/scsi/libiscsi.c | 2 +-
drivers/scsi/scsi_transport_iscsi.c | 2 +-
3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 1d669e4..4b9f80d 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -272,7 +272,7 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
if (shost->transportt->create_work_queue) {
snprintf(shost->work_q_name, sizeof(shost->work_q_name),
"scsi_wq_%d", shost->host_no);
- shost->work_q = create_singlethread_workqueue(
+ shost->work_q = create_singlethread_workqueue_noorder(
shost->work_q_name);
if (!shost->work_q) {
error = -EINVAL;
@@ -487,7 +487,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
}

shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
- WQ_UNBOUND | WQ_MEM_RECLAIM,
+ WQ_UNBOUND | WQ_MEM_RECLAIM | WQ_SYSFS | __WQ_ORDERED_DISABLE,
1, shost->host_no);
if (!shost->tmf_work_q) {
shost_printk(KERN_WARNING, shost,
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 70b99c0..6808cf3 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -2627,7 +2627,7 @@ struct Scsi_Host *iscsi_host_alloc(struct scsi_host_template *sht,
if (xmit_can_sleep) {
snprintf(ihost->workq_name, sizeof(ihost->workq_name),
"iscsi_q_%d", shost->host_no);
- ihost->workq = create_singlethread_workqueue(ihost->workq_name);
+ ihost->workq = create_singlethread_workqueue_noorder(ihost->workq_name);
if (!ihost->workq)
goto free_host;
}
diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index dfc726f..d07a0e4 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -4602,7 +4602,7 @@ static __init int iscsi_transport_init(void)
goto unregister_flashnode_bus;
}

- iscsi_eh_timer_workq = create_singlethread_workqueue("iscsi_eh");
+ iscsi_eh_timer_workq = create_singlethread_workqueue_noorder("iscsi_eh");
if (!iscsi_eh_timer_workq) {
err = -ENOMEM;
goto release_nls;
--
2.9.5

[Mike Christie]

This patch seems ok for the iscsi, fc, tmf, and non transport class scan
uses. We are either heavy handed with flushes or did not need ordering.

I don't know about the zfcp use though, so I cc'd the developers listed
as maintainers. It looks like for zfcp we can do:

zfcp_scsi_rport_register->fc_remote_port_add->fc_remote_port_create->scsi_queue_work
to scan the scsi target on the rport.

and then zfcp_scsi_rport_register can call zfcp_unit_queue_scsi_scan->
scsi_queue_work which will scan for a specific lun.

It looks ok if those are not ordered, but I would get their review to
make sure.

[Benjamin Block]

Thx for the notice.

>
> zfcp_scsi_rport_register->fc_remote_port_add->fc_remote_port_create->scsi_queue_work
> to scan the scsi target on the rport.
>
> and then zfcp_scsi_rport_register can call zfcp_unit_queue_scsi_scan->
> scsi_queue_work which will scan for a specific lun.
>
> It looks ok if those are not ordered, but I would get their review to make
> sure.

I am not aware of any temporal requirements of those LUN-scans, so I
think making them not explicitly ordered shouldn't hurt us.

The target scan itself is protected again by `shost->scan_mutex`.. so
all fine I think.

--
Best Regards, Benjamin Block / Linux on IBM Z Kernel Development / IBM Systems
IBM Deutschland Research & Development GmbH / https://www.ibm.com/privacy
Vorsitz. AufsR.: Gregor Pillen / Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen / Registergericht: AmtsG Stuttgart, HRB 243294