[PATCH v3 5/7] libsas: add a new workqueue to run probe/destruct discovery event

[Yijing Wang <wangyijing@huawei.com>]

Sometimes, we want sync libsas probe or destruct in sas discovery work,
like when libsas revalidate domain. We need to split probe and destruct
work from the scsi host workqueue.

Signed-off-by: Yijing Wang <wangyijing@huawei.com>
CC: John Garry <john.garry@huawei.com>
CC: Johannes Thumshirn <jthumshirn@suse.de>
CC: Ewan Milne <emilne@redhat.com>
CC: Christoph Hellwig <hch@lst.de>
CC: Tomas Henzl <thenzl@redhat.com>
CC: Dan Williams <dan.j.williams@intel.com>
---
 drivers/scsi/libsas/sas_discover.c | 13 ++++++++++++-
 drivers/scsi/libsas/sas_init.c     |  8 ++++++++
 include/scsi/libsas.h              |  1 +
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index 5d4a3a8..a25d648 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -559,7 +559,18 @@ static void sas_chain_work(struct sas_ha_struct *ha, struct sas_work *sw)
 	 * not racing against draining
 	 */
 	sas_port_get(port);
-	ret = scsi_queue_work(ha->core.shost, &sw->work);
+	/*
+	 * discovery event probe and destruct would be called in other
+	 * discovery event like discover domain and revalidate domain
+	 * events, in some cases, we need to sync execute probe and destruct
+	 * events, so run probe and destruct discover events except in a new
+	 * workqueue.
+	 */
+	if (ev->type == DISCE_PROBE || ev->type == DISCE_DESTRUCT)
+		ret = queue_work(ha->disc_q, &sw->work);
+	else
+		ret = scsi_queue_work(ha->core.shost, &sw->work);
+
 	if (ret != 1)
 		sas_port_put(port);
 }
diff --git a/drivers/scsi/libsas/sas_init.c b/drivers/scsi/libsas/sas_init.c
index 2f3b736..df1d78b 100644
--- a/drivers/scsi/libsas/sas_init.c
+++ b/drivers/scsi/libsas/sas_init.c
@@ -152,6 +152,13 @@ int sas_register_ha(struct sas_ha_struct *sas_ha)
 	if (!sas_ha->event_q)
 		goto Undo_ports;
 
+	snprintf(name, 64, "%s_disc_q", dev_name(sas_ha->dev));
+	sas_ha->disc_q = create_singlethread_workqueue(name);
+	if(!sas_ha->disc_q) {
+		destroy_workqueue(sas_ha->event_q);
+		goto Undo_ports;
+	}
+
 	INIT_LIST_HEAD(&sas_ha->eh_done_q);
 	INIT_LIST_HEAD(&sas_ha->eh_ata_q);
 
@@ -187,6 +194,7 @@ int sas_unregister_ha(struct sas_ha_struct *sas_ha)
 	__sas_drain_work(sas_ha);
 	mutex_unlock(&sas_ha->drain_mutex);
 	destroy_workqueue(sas_ha->event_q);
+	destroy_workqueue(sas_ha->disc_q);
 
 	return 0;
 }
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index c2ef05e..4bcb9fe 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -406,6 +406,7 @@ struct sas_ha_struct {
 	struct device *dev;	  /* should be set */
 	struct module *lldd_module; /* should be set */
 	struct workqueue_struct *event_q;
+	struct workqueue_struct *disc_q;
 
 	u8 *sas_addr;		  /* must be set */
 	u8 hashed_sas_addr[HASHED_SAS_ADDR_SIZE];
-- 
2.5.0