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>
diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index dd0f72c..cfaeed2 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -415,9 +415,9 @@
 				* 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 */