xen/scsiback: Replace a waitqueue and a counter by a completion

This patch simplifies the implementation of the scsiback driver
but does not change its behavior.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: David Disseldorp <ddiss@suse.de>
Cc: xen-devel@lists.xenproject.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/xen/xen-scsiback.c

@@ -135,8 +135,7 @@ struct vscsibk_pend {
 
 	struct se_cmd se_cmd;
 
-	atomic_t tmr_complete;
-	wait_queue_head_t tmr_wait;
+	struct completion tmr_done;
 };
 
 #define VSCSI_DEFAULT_SESSION_TAGS	128
@@ -600,7 +599,7 @@ static void scsiback_device_action(struct vscsibk_pend *pending_req,
 	u64 unpacked_lun = pending_req->v2p->lun;
 	int rc, err = FAILED;
 
-	init_waitqueue_head(&pending_req->tmr_wait);
+	init_completion(&pending_req->tmr_done);
 
 	rc = target_submit_tmr(&pending_req->se_cmd, nexus->tvn_se_sess,
 			       &pending_req->sense_buffer[0],
@@ -609,8 +608,7 @@ static void scsiback_device_action(struct vscsibk_pend *pending_req,
 	if (rc)
 		goto err;
 
-	wait_event(pending_req->tmr_wait,
-		   atomic_read(&pending_req->tmr_complete));
+	wait_for_completion(&pending_req->tmr_done);
 
 	err = (se_cmd->se_tmr_req->response == TMR_FUNCTION_COMPLETE) ?
 		SUCCESS : FAILED;
@@ -1443,8 +1441,7 @@ static void scsiback_queue_tm_rsp(struct se_cmd *se_cmd)
 	struct vscsibk_pend *pending_req = container_of(se_cmd,
 				struct vscsibk_pend, se_cmd);
 
-	atomic_set(&pending_req->tmr_complete, 1);
-	wake_up(&pending_req->tmr_wait);
+	complete(&pending_req->tmr_done);
 }
 
 static void scsiback_aborted_task(struct se_cmd *se_cmd)