scsi: libsas: only clear phy->in_shutdown after shutdown event done

When the event queue is full of phy up and down events and reached the
threshold, we will queue a shutdown-event, and set phy->in_shutdown so that
we will not queue a shutdown-event again. But before the shutdown-event can
be executed, every phy-down event will clear
phy->in_shutdown and a new shutdown-event will be queued. The queue will
be full of these shutdown-events.

Fix this by only clear phy->in_shutdown in sas_phye_shutdown(), that is
after the first shutdown-event has been executed.

Fixes: f12486e06ae8 ("scsi: libsas: shut down the PHY if events reached the threshold")
Signed-off-by: Jason Yan <[e-mail]>
CC: John Garry <[e-mail]>
CC: Johannes Thumshirn <[e-mail]>
CC: Ewan Milne <[e-mail]>
CC: Christoph Hellwig <[e-mail]>
CC: Tomas Henzl <[e-mail]>
CC: Dan Williams <[e-mail]>
CC: Hannes Reinecke <[e-mail]>
Reviewed-by: John Garry <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/libsas/sas_phy.c

···
 	struct asd_sas_event *ev = to_asd_sas_event(work);
 	struct asd_sas_phy *phy = ev->phy;
 
-	phy->in_shutdown = 0;
 	phy->error = 0;
 	sas_deform_port(phy, 1);
 }
···
 	struct asd_sas_event *ev = to_asd_sas_event(work);
 	struct asd_sas_phy *phy = ev->phy;
 
-	phy->in_shutdown = 0;
 	phy->error = 0;
 }
 
···
 				  ret);
 	} else
 		pr_notice("phy%d is not enabled, cannot shutdown\n", phy->id);
+	phy->in_shutdown = 0;
 }
 
 /* ---------- Phy class registration ---------- */