[PATCH v3 4/7] libsas: add sas event wait-complete support

[Yijing Wang]

Introduce wait-complete for libsas sas event processing,
execute sas port create/destruct in sync.

Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
CC: John Garry <john.garry@xxxxxxxxxx>
CC: Johannes Thumshirn <jthumshirn@xxxxxxx>
CC: Ewan Milne <emilne@xxxxxxxxxx>
CC: Christoph Hellwig <hch@xxxxxx>
CC: Tomas Henzl <thenzl@xxxxxxxxxx>
CC: Dan Williams <dan.j.williams@xxxxxxxxx>
---
 drivers/scsi/libsas/sas_discover.c | 41 ++++++++++++++++++++++++++++----------
 drivers/scsi/libsas/sas_internal.h | 34 +++++++++++++++++++++++++++++++
 drivers/scsi/libsas/sas_port.c     |  4 ++++
 include/scsi/libsas.h              |  5 ++++-
 4 files changed, 72 insertions(+), 12 deletions(-)

diff --git a/drivers/scsi/libsas/sas_discover.c b/drivers/scsi/libsas/sas_discover.c
index 60de662..5d4a3a8 100644
--- a/drivers/scsi/libsas/sas_discover.c
+++ b/drivers/scsi/libsas/sas_discover.c
@@ -525,16 +525,43 @@ static void sas_revalidate_domain(struct work_struct *work)
 	mutex_unlock(&ha->disco_mutex);
 }
 
+static const work_func_t sas_event_fns[DISC_NUM_EVENTS] = {
+	[DISCE_DISCOVER_DOMAIN] = sas_discover_domain,
+	[DISCE_REVALIDATE_DOMAIN] = sas_revalidate_domain,
+	[DISCE_PROBE] = sas_probe_devices,
+	[DISCE_SUSPEND] = sas_suspend_devices,
+	[DISCE_RESUME] = sas_resume_devices,
+	[DISCE_DESTRUCT] = sas_destruct_devices,
+};
+
+/* a simple wrapper for sas discover event funtions */
+static void sas_discover_common_fn(struct work_struct *work)
+{
+	struct sas_discovery_event *ev = to_sas_discovery_event(work);
+	struct asd_sas_port *port = ev->port;
+
+	sas_event_fns[ev->type](work);
+	sas_port_put(port);
+}
+
+
 /* ---------- Events ---------- */
 
 static void sas_chain_work(struct sas_ha_struct *ha, struct sas_work *sw)
 {
+	int ret;
+	struct sas_discovery_event *ev = to_sas_discovery_event(&sw->work);
+	struct asd_sas_port *port = ev->port;
+
 	/* chained work is not subject to SA_HA_DRAINING or
 	 * SAS_HA_REGISTERED, because it is either submitted in the
 	 * workqueue, or known to be submitted from a context that is
 	 * not racing against draining
 	 */
-	scsi_queue_work(ha->core.shost, &sw->work);
+	sas_port_get(port);
+	ret = scsi_queue_work(ha->core.shost, &sw->work);
+	if (ret != 1)
+		sas_port_put(port);
 }
 
 static void sas_chain_event(int event, unsigned long *pending,
@@ -575,18 +602,10 @@ void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *port)
 {
 	int i;
 
-	static const work_func_t sas_event_fns[DISC_NUM_EVENTS] = {
-		[DISCE_DISCOVER_DOMAIN] = sas_discover_domain,
-		[DISCE_REVALIDATE_DOMAIN] = sas_revalidate_domain,
-		[DISCE_PROBE] = sas_probe_devices,
-		[DISCE_SUSPEND] = sas_suspend_devices,
-		[DISCE_RESUME] = sas_resume_devices,
-		[DISCE_DESTRUCT] = sas_destruct_devices,
-	};
-
 	disc->pending = 0;
 	for (i = 0; i < DISC_NUM_EVENTS; i++) {
-		INIT_SAS_WORK(&disc->disc_work[i].work, sas_event_fns[i]);
+		INIT_SAS_WORK(&disc->disc_work[i].work, sas_discover_common_fn);
 		disc->disc_work[i].port = port;
+		disc->disc_work[i].type = i;
 	}
 }
diff --git a/drivers/scsi/libsas/sas_internal.h b/drivers/scsi/libsas/sas_internal.h
index f03ce64..890b5d26 100644
--- a/drivers/scsi/libsas/sas_internal.h
+++ b/drivers/scsi/libsas/sas_internal.h
@@ -100,6 +100,40 @@ void sas_free_device(struct kref *kref);
 extern const work_func_t sas_phy_event_fns[PHY_NUM_EVENTS];
 extern const work_func_t sas_port_event_fns[PORT_NUM_EVENTS];
 
+static void sas_complete_event(struct kref *kref)
+{
+	struct asd_sas_port *port = container_of(kref, struct asd_sas_port, ref);
+
+	complete_all(&port->completion);
+}
+
+static inline void sas_port_put(struct asd_sas_port *port)
+{
+	if (port->is_sync)
+		kref_put(&port->ref, sas_complete_event);
+}
+
+static inline void sas_port_wait_init(struct asd_sas_port *port)
+{
+	init_completion(&port->completion);
+	kref_init(&port->ref);
+	port->is_sync = true;
+}
+
+static inline void sas_port_wait_completion(
+		struct asd_sas_port *port)
+{
+	sas_port_put(port);
+	wait_for_completion(&port->completion);
+	port->is_sync = false;
+}
+
+static inline void sas_port_get(struct asd_sas_port *port)
+{
+	if (port && port->is_sync)
+		kref_get(&port->ref);
+}
+
 #ifdef CONFIG_SCSI_SAS_HOST_SMP
 extern int sas_smp_host_handler(struct Scsi_Host *shost, struct request *req,
 				struct request *rsp);
diff --git a/drivers/scsi/libsas/sas_port.c b/drivers/scsi/libsas/sas_port.c
index 9326628..d589adb 100644
--- a/drivers/scsi/libsas/sas_port.c
+++ b/drivers/scsi/libsas/sas_port.c
@@ -191,7 +191,9 @@ static void sas_form_port(struct asd_sas_phy *phy)
 	if (si->dft->lldd_port_formed)
 		si->dft->lldd_port_formed(phy);
 
+	sas_port_wait_init(port);
 	sas_discover_event(phy->port, DISCE_DISCOVER_DOMAIN);
+	sas_port_wait_completion(port);
 }
 
 /**
@@ -218,7 +220,9 @@ void sas_deform_port(struct asd_sas_phy *phy, int gone)
 		dev->pathways--;
 
 	if (port->num_phys == 1) {
+		sas_port_wait_init(port);
 		sas_unregister_domain_devices(port, gone);
+		sas_port_wait_completion(port);
 		sas_port_delete(port->port);
 		port->port = NULL;
 	} else {
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index a01ca42..c2ef05e 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -242,6 +242,7 @@ static inline void INIT_SAS_WORK(struct sas_work *sw, void (*fn)(struct work_str
 struct sas_discovery_event {
 	struct sas_work work;
 	struct asd_sas_port *port;
+	enum discover_event	type;
 };
 
 static inline struct sas_discovery_event *to_sas_discovery_event(struct work_struct *work)
@@ -273,7 +274,9 @@ struct asd_sas_port {
 
 	struct sas_work work;
 	int suspended;
-
+	struct kref ref;
+	struct completion completion;
+	bool is_sync;
 /* public: */
 	int id;
 
-- 
2.5.0