[SCSI] libsas: poll for ata device readiness after reset

Use ata_wait_after_reset() to poll for link recovery after a reset.
This combined with sas_ha->eh_mutex prevents expander rediscovery from
probing phys in an intermediate state.  Local discovery does not have a
mechanism to filter link status changes during this timeout, so it
remains the responsibility of lldds to prevent premature port teardown.
Although once all lldd's support ->lldd_ata_check_ready() that could be
used as a gate to local port teardown.

The signature fis is re-transmitted when the link comes back so we
should be revalidating the ata device class, but that is left to a future
patch.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
index 7c59f97..32e417e 100644
--- a/drivers/scsi/libsas/sas_expander.c
+++ b/drivers/scsi/libsas/sas_expander.c
@@ -125,7 +125,11 @@
 		    task->task_status.stat == SAS_DATA_OVERRUN) {
 			res = -EMSGSIZE;
 			break;
-		} else {
+		}
+		if (task->task_status.resp == SAS_TASK_UNDELIVERED &&
+		    task->task_status.stat == SAS_DEVICE_UNKNOWN)
+			break;
+		else {
 			SAS_DPRINTK("%s: task to dev %016llx response: 0x%x "
 				    "status 0x%x\n", __func__,
 				    SAS_ADDR(dev->sas_addr),
@@ -1648,8 +1652,8 @@
 	return res;
 }
 
-static int sas_get_phy_attached_sas_addr(struct domain_device *dev,
-					 int phy_id, u8 *attached_sas_addr)
+int sas_get_phy_attached_sas_addr(struct domain_device *dev, int phy_id,
+				  u8 *attached_sas_addr)
 {
 	int res;
 	struct smp_resp *disc_resp;