scsi: sas: scsi_queue_work can fail, so make callers aware

libsas uses scsi_queue_work() to queue its internal event notifications.
scsi_queue_work() can return -EINVAL if the work queue doesn't exist and
it does call queue_work() which can return false if the work is already
queued.

Make the SAS event code capable of returning errors up to the caller,
which is handy when changing to dynamically allocated work in libsas
as well, as discussed here: https://lkml.org/lkml/2017/6/14/121.

[mkp: fixed typo]
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/libsas/sas_event.c

@@ -27,30 +27,38 @@
 #include "sas_internal.h"
 #include "sas_dump.h"
 
-void sas_queue_work(struct sas_ha_struct *ha, struct sas_work *sw)
+int sas_queue_work(struct sas_ha_struct *ha, struct sas_work *sw)
 {
+	int rc = 0;
+
 	if (!test_bit(SAS_HA_REGISTERED, &ha->state))
-		return;
+		return 0;
 
 	if (test_bit(SAS_HA_DRAINING, &ha->state)) {
 		/* add it to the defer list, if not already pending */
 		if (list_empty(&sw->drain_node))
 			list_add(&sw->drain_node, &ha->defer_q);
 	} else
-		scsi_queue_work(ha->core.shost, &sw->work);
+		rc = scsi_queue_work(ha->core.shost, &sw->work);
+
+	return rc;
 }
 
-static void sas_queue_event(int event, unsigned long *pending,
+static int sas_queue_event(int event, unsigned long *pending,
 			    struct sas_work *work,
 			    struct sas_ha_struct *ha)
 {
+	int rc = 0;
+
 	if (!test_and_set_bit(event, pending)) {
 		unsigned long flags;
 
 		spin_lock_irqsave(&ha->lock, flags);
-		sas_queue_work(ha, work);
+		rc = sas_queue_work(ha, work);
 		spin_unlock_irqrestore(&ha->lock, flags);
 	}
+
+	return rc;
 }
 
 
@@ -116,32 +124,32 @@ void sas_enable_revalidation(struct sas_ha_struct *ha)
 	mutex_unlock(&ha->disco_mutex);
 }
 
-static void notify_ha_event(struct sas_ha_struct *sas_ha, enum ha_event event)
+static int notify_ha_event(struct sas_ha_struct *sas_ha, enum ha_event event)
 {
 	BUG_ON(event >= HA_NUM_EVENTS);
 
-	sas_queue_event(event, &sas_ha->pending,
-			&sas_ha->ha_events[event].work, sas_ha);
+	return sas_queue_event(event, &sas_ha->pending,
+			       &sas_ha->ha_events[event].work, sas_ha);
 }
 
-static void notify_port_event(struct asd_sas_phy *phy, enum port_event event)
+static int notify_port_event(struct asd_sas_phy *phy, enum port_event event)
 {
 	struct sas_ha_struct *ha = phy->ha;
 
 	BUG_ON(event >= PORT_NUM_EVENTS);
 
-	sas_queue_event(event, &phy->port_events_pending,
-			&phy->port_events[event].work, ha);
+	return sas_queue_event(event, &phy->port_events_pending,
+			       &phy->port_events[event].work, ha);
 }
 
-void sas_notify_phy_event(struct asd_sas_phy *phy, enum phy_event event)
+int sas_notify_phy_event(struct asd_sas_phy *phy, enum phy_event event)
 {
 	struct sas_ha_struct *ha = phy->ha;
 
 	BUG_ON(event >= PHY_NUM_EVENTS);
 
-	sas_queue_event(event, &phy->phy_events_pending,
-			&phy->phy_events[event].work, ha);
+	return sas_queue_event(event, &phy->phy_events_pending,
+			       &phy->phy_events[event].work, ha);
 }
 
 int sas_init_events(struct sas_ha_struct *sas_ha)

drivers/scsi/libsas/sas_internal.h

@@ -76,7 +76,7 @@ void sas_porte_broadcast_rcvd(struct work_struct *work);
 void sas_porte_link_reset_err(struct work_struct *work);
 void sas_porte_timer_event(struct work_struct *work);
 void sas_porte_hard_reset(struct work_struct *work);
-void sas_queue_work(struct sas_ha_struct *ha, struct sas_work *sw);
+int sas_queue_work(struct sas_ha_struct *ha, struct sas_work *sw);
 
 int sas_notify_lldd_dev_found(struct domain_device *);
 void sas_notify_lldd_dev_gone(struct domain_device *);
@@ -85,7 +85,7 @@ int sas_smp_phy_control(struct domain_device *dev, int phy_id,
 			enum phy_func phy_func, struct sas_phy_linkrates *);
 int sas_smp_get_phy_events(struct sas_phy *phy);
 
-void sas_notify_phy_event(struct asd_sas_phy *phy, enum phy_event event);
+int sas_notify_phy_event(struct asd_sas_phy *phy, enum phy_event event);
 void sas_device_set_phy(struct domain_device *dev, struct sas_port *port);
 struct domain_device *sas_find_dev_by_rphy(struct sas_rphy *rphy);
 struct domain_device *sas_ex_to_ata(struct domain_device *ex_dev, int phy_id);

include/scsi/libsas.h

@@ -415,9 +415,9 @@ struct sas_ha_struct {
 				* their siblings when forming wide ports */
 
 	/* LLDD calls these to notify the class of an event. */
-	void (*notify_ha_event)(struct sas_ha_struct *, enum ha_event);
-	void (*notify_port_event)(struct asd_sas_phy *, enum port_event);
-	void (*notify_phy_event)(struct asd_sas_phy *, enum phy_event);
+	int (*notify_ha_event)(struct sas_ha_struct *, enum ha_event);
+	int (*notify_port_event)(struct asd_sas_phy *, enum port_event);
+	int (*notify_phy_event)(struct asd_sas_phy *, enum phy_event);
 
 	void *lldd_ha;		  /* not touched by sas class code */