1 files changed, 96 insertions, 45 deletions

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 7ba58c39146f..448753021724 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -78,6 +78,7 @@ enum blkif_state {
 	BLKIF_STATE_DISCONNECTED,
 	BLKIF_STATE_CONNECTED,
 	BLKIF_STATE_SUSPENDED,
+	BLKIF_STATE_ERROR,
 };
 
 struct grant {
@@ -87,6 +88,7 @@ struct grant {
 };
 
 enum blk_req_status {
+	REQ_PROCESSING,
 	REQ_WAITING,
 	REQ_DONE,
 	REQ_ERROR,
@@ -534,10 +536,10 @@ static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
 
 	id = get_id_from_freelist(rinfo);
 	rinfo->shadow[id].request = req;
-	rinfo->shadow[id].status = REQ_WAITING;
+	rinfo->shadow[id].status = REQ_PROCESSING;
 	rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
 
-	(*ring_req)->u.rw.id = id;
+	rinfo->shadow[id].req.u.rw.id = id;
 
 	return id;
 }
@@ -545,11 +547,12 @@ static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
 {
 	struct blkfront_info *info = rinfo->dev_info;
-	struct blkif_request *ring_req;
+	struct blkif_request *ring_req, *final_ring_req;
 	unsigned long id;
 
 	/* Fill out a communications ring structure. */
-	id = blkif_ring_get_request(rinfo, req, &ring_req);
+	id = blkif_ring_get_request(rinfo, req, &final_ring_req);
+	ring_req = &rinfo->shadow[id].req;
 
 	ring_req->operation = BLKIF_OP_DISCARD;
 	ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
@@ -560,8 +563,9 @@ static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_inf
 	else
 		ring_req->u.discard.flag = 0;
 
-	/* Keep a private copy so we can reissue requests when recovering. */
-	rinfo->shadow[id].req = *ring_req;
+	/* Copy the request to the ring page. */
+	*final_ring_req = *ring_req;
+	rinfo->shadow[id].status = REQ_WAITING;
 
 	return 0;
 }
@@ -694,6 +698,7 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri
 {
 	struct blkfront_info *info = rinfo->dev_info;
 	struct blkif_request *ring_req, *extra_ring_req = NULL;
+	struct blkif_request *final_ring_req, *final_extra_ring_req = NULL;
 	unsigned long id, extra_id = NO_ASSOCIATED_ID;
 	bool require_extra_req = false;
 	int i;
@@ -738,7 +743,8 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri
 	}
 
 	/* Fill out a communications ring structure. */
-	id = blkif_ring_get_request(rinfo, req, &ring_req);
+	id = blkif_ring_get_request(rinfo, req, &final_ring_req);
+	ring_req = &rinfo->shadow[id].req;
 
 	num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
 	num_grant = 0;
@@ -789,7 +795,9 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri
 		ring_req->u.rw.nr_segments = num_grant;
 		if (unlikely(require_extra_req)) {
 			extra_id = blkif_ring_get_request(rinfo, req,
-							  &extra_ring_req);
+							  &final_extra_ring_req);
+			extra_ring_req = &rinfo->shadow[extra_id].req;
+
 			/*
 			 * Only the first request contains the scatter-gather
 			 * list.
@@ -831,10 +839,13 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri
 	if (setup.segments)
 		kunmap_atomic(setup.segments);
 
-	/* Keep a private copy so we can reissue requests when recovering. */
-	rinfo->shadow[id].req = *ring_req;
-	if (unlikely(require_extra_req))
-		rinfo->shadow[extra_id].req = *extra_ring_req;
+	/* Copy request(s) to the ring page. */
+	*final_ring_req = *ring_req;
+	rinfo->shadow[id].status = REQ_WAITING;
+	if (unlikely(require_extra_req)) {
+		*final_extra_ring_req = *extra_ring_req;
+		rinfo->shadow[extra_id].status = REQ_WAITING;
+	}
 
 	if (new_persistent_gnts)
 		gnttab_free_grant_references(setup.gref_head);
@@ -1408,8 +1419,8 @@ static enum blk_req_status blkif_rsp_to_req_status(int rsp)
 static int blkif_get_final_status(enum blk_req_status s1,
 				  enum blk_req_status s2)
 {
-	BUG_ON(s1 == REQ_WAITING);
-	BUG_ON(s2 == REQ_WAITING);
+	BUG_ON(s1 < REQ_DONE);
+	BUG_ON(s2 < REQ_DONE);
 
 	if (s1 == REQ_ERROR || s2 == REQ_ERROR)
 		return BLKIF_RSP_ERROR;
@@ -1442,7 +1453,7 @@ static bool blkif_completion(unsigned long *id,
 		s->status = blkif_rsp_to_req_status(bret->status);
 
 		/* Wait the second response if not yet here. */
-		if (s2->status == REQ_WAITING)
+		if (s2->status < REQ_DONE)
 			return 0;
 
 		bret->status = blkif_get_final_status(s->status,
@@ -1550,65 +1561,92 @@ static bool blkif_completion(unsigned long *id,
 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 {
 	struct request *req;
-	struct blkif_response *bret;
+	struct blkif_response bret;
 	RING_IDX i, rp;
 	unsigned long flags;
 	struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
 	struct blkfront_info *info = rinfo->dev_info;
+	unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS;
 
-	if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
+	if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
+		xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
 		return IRQ_HANDLED;
+	}
 
 	spin_lock_irqsave(&rinfo->ring_lock, flags);
  again:
-	rp = rinfo->ring.sring->rsp_prod;
-	rmb(); /* Ensure we see queued responses up to 'rp'. */
+	rp = READ_ONCE(rinfo->ring.sring->rsp_prod);
+	virt_rmb(); /* Ensure we see queued responses up to 'rp'. */
+	if (RING_RESPONSE_PROD_OVERFLOW(&rinfo->ring, rp)) {
+		pr_alert("%s: illegal number of responses %u\n",
+			 info->gd->disk_name, rp - rinfo->ring.rsp_cons);
+		goto err;
+	}
 
 	for (i = rinfo->ring.rsp_cons; i != rp; i++) {
 		unsigned long id;
+		unsigned int op;
+
+		eoiflag = 0;
+
+		RING_COPY_RESPONSE(&rinfo->ring, i, &bret);
+		id = bret.id;
 
-		bret = RING_GET_RESPONSE(&rinfo->ring, i);
-		id   = bret->id;
 		/*
 		 * The backend has messed up and given us an id that we would
 		 * never have given to it (we stamp it up to BLK_RING_SIZE -
 		 * look in get_id_from_freelist.
 		 */
 		if (id >= BLK_RING_SIZE(info)) {
-			WARN(1, "%s: response to %s has incorrect id (%ld)\n",
-			     info->gd->disk_name, op_name(bret->operation), id);
-			/* We can't safely get the 'struct request' as
-			 * the id is busted. */
-			continue;
+			pr_alert("%s: response has incorrect id (%ld)\n",
+				 info->gd->disk_name, id);
+			goto err;
 		}
+		if (rinfo->shadow[id].status != REQ_WAITING) {
+			pr_alert("%s: response references no pending request\n",
+				 info->gd->disk_name);
+			goto err;
+		}
+
+		rinfo->shadow[id].status = REQ_PROCESSING;
 		req  = rinfo->shadow[id].request;
 
-		if (bret->operation != BLKIF_OP_DISCARD) {
+		op = rinfo->shadow[id].req.operation;
+		if (op == BLKIF_OP_INDIRECT)
+			op = rinfo->shadow[id].req.u.indirect.indirect_op;
+		if (bret.operation != op) {
+			pr_alert("%s: response has wrong operation (%u instead of %u)\n",
+				 info->gd->disk_name, bret.operation, op);
+			goto err;
+		}
+
+		if (bret.operation != BLKIF_OP_DISCARD) {
 			/*
 			 * We may need to wait for an extra response if the
 			 * I/O request is split in 2
 			 */
-			if (!blkif_completion(&id, rinfo, bret))
+			if (!blkif_completion(&id, rinfo, &bret))
 				continue;
 		}
 
 		if (add_id_to_freelist(rinfo, id)) {
 			WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
-			     info->gd->disk_name, op_name(bret->operation), id);
+			     info->gd->disk_name, op_name(bret.operation), id);
 			continue;
 		}
 
-		if (bret->status == BLKIF_RSP_OKAY)
+		if (bret.status == BLKIF_RSP_OKAY)
 			blkif_req(req)->error = BLK_STS_OK;
 		else
 			blkif_req(req)->error = BLK_STS_IOERR;
 
-		switch (bret->operation) {
+		switch (bret.operation) {
 		case BLKIF_OP_DISCARD:
-			if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
+			if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
 				struct request_queue *rq = info->rq;
-				printk(KERN_WARNING "blkfront: %s: %s op failed\n",
-					   info->gd->disk_name, op_name(bret->operation));
+
+				pr_warn_ratelimited("blkfront: %s: %s op failed\n",
+					   info->gd->disk_name, op_name(bret.operation));
 				blkif_req(req)->error = BLK_STS_NOTSUPP;
 				info->feature_discard = 0;
 				info->feature_secdiscard = 0;
@@ -1618,15 +1656,15 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 			break;
 		case BLKIF_OP_FLUSH_DISKCACHE:
 		case BLKIF_OP_WRITE_BARRIER:
-			if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
-				printk(KERN_WARNING "blkfront: %s: %s op failed\n",
-				       info->gd->disk_name, op_name(bret->operation));
+			if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
+				pr_warn_ratelimited("blkfront: %s: %s op failed\n",
+				       info->gd->disk_name, op_name(bret.operation));
 				blkif_req(req)->error = BLK_STS_NOTSUPP;
 			}
-			if (unlikely(bret->status == BLKIF_RSP_ERROR &&
+			if (unlikely(bret.status == BLKIF_RSP_ERROR &&
 				     rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
-				printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
-				       info->gd->disk_name, op_name(bret->operation));
+				pr_warn_ratelimited("blkfront: %s: empty %s op failed\n",
+				       info->gd->disk_name, op_name(bret.operation));
 				blkif_req(req)->error = BLK_STS_NOTSUPP;
 			}
 			if (unlikely(blkif_req(req)->error)) {
@@ -1639,9 +1677,10 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 			/* fall through */
 		case BLKIF_OP_READ:
 		case BLKIF_OP_WRITE:
-			if (unlikely(bret->status != BLKIF_RSP_OKAY))
-				dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
-					"request: %x\n", bret->status);
+			if (unlikely(bret.status != BLKIF_RSP_OKAY))
+				dev_dbg_ratelimited(&info->xbdev->dev,
+					"Bad return from blkdev data request: %#x\n",
+					bret.status);
 
 			break;
 		default:
@@ -1665,6 +1704,18 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 
 	spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 
+	xen_irq_lateeoi(irq, eoiflag);
+
+	return IRQ_HANDLED;
+
+ err:
+	info->connected = BLKIF_STATE_ERROR;
+
+	spin_unlock_irqrestore(&rinfo->ring_lock, flags);
+
+	/* No EOI in order to avoid further interrupts. */
+
+	pr_alert("%s disabled for further use\n", info->gd->disk_name);
 	return IRQ_HANDLED;
 }
 
@@ -1703,8 +1754,8 @@ static int setup_blkring(struct xenbus_device *dev,
 	if (err)
 		goto fail;
 
-	err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
-					"blkif", rinfo);
+	err = bind_evtchn_to_irqhandler_lateeoi(rinfo->evtchn, blkif_interrupt,
+						0, "blkif", rinfo);
 	if (err <= 0) {
 		xenbus_dev_fatal(dev, err,
 				 "bind_evtchn_to_irqhandler failed");