2 files changed, 183 insertions, 74 deletions

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 7f8f16bad75..cfc1d65c457 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -291,7 +291,7 @@ static void srp_free_target_ib(struct srp_target_port *target)
 
 	for (i = 0; i < SRP_RQ_SIZE; ++i)
 		srp_free_iu(target->srp_host, target->rx_ring[i]);
-	for (i = 0; i < SRP_SQ_SIZE + 1; ++i)
+	for (i = 0; i < SRP_SQ_SIZE; ++i)
 		srp_free_iu(target->srp_host, target->tx_ring[i]);
 }
 
@@ -811,6 +811,75 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
 	return len;
 }
 
+/*
+ * Must be called with target->scsi_host->host_lock held to protect
+ * req_lim and tx_head.  Lock cannot be dropped between call here and
+ * call to __srp_post_send().
+ *
+ * Note:
+ * An upper limit for the number of allocated information units for each
+ * request type is:
+ * - SRP_IU_CMD: SRP_CMD_SQ_SIZE, since the SCSI mid-layer never queues
+ *   more than Scsi_Host.can_queue requests.
+ * - SRP_IU_TSK_MGMT: SRP_TSK_MGMT_SQ_SIZE.
+ * - SRP_IU_RSP: 1, since a conforming SRP target never sends more than
+ *   one unanswered SRP request to an initiator.
+ */
+static struct srp_iu *__srp_get_tx_iu(struct srp_target_port *target,
+				      enum srp_iu_type iu_type)
+{
+	s32 rsv = (iu_type == SRP_IU_TSK_MGMT) ? 0 : SRP_TSK_MGMT_SQ_SIZE;
+	struct srp_iu *iu;
+
+	srp_send_completion(target->send_cq, target);
+
+	if (target->tx_head - target->tx_tail >= SRP_SQ_SIZE)
+		return NULL;
+
+	/* Initiator responses to target requests do not consume credits */
+	if (target->req_lim <= rsv && iu_type != SRP_IU_RSP) {
+		++target->zero_req_lim;
+		return NULL;
+	}
+
+	iu = target->tx_ring[target->tx_head & SRP_SQ_MASK];
+	iu->type = iu_type;
+	return iu;
+}
+
+/*
+ * Must be called with target->scsi_host->host_lock held to protect
+ * req_lim and tx_head.
+ */
+static int __srp_post_send(struct srp_target_port *target,
+			   struct srp_iu *iu, int len)
+{
+	struct ib_sge list;
+	struct ib_send_wr wr, *bad_wr;
+	int ret = 0;
+
+	list.addr   = iu->dma;
+	list.length = len;
+	list.lkey   = target->srp_host->srp_dev->mr->lkey;
+
+	wr.next       = NULL;
+	wr.wr_id      = target->tx_head & SRP_SQ_MASK;
+	wr.sg_list    = &list;
+	wr.num_sge    = 1;
+	wr.opcode     = IB_WR_SEND;
+	wr.send_flags = IB_SEND_SIGNALED;
+
+	ret = ib_post_send(target->qp, &wr, &bad_wr);
+
+	if (!ret) {
+		++target->tx_head;
+		if (iu->type != SRP_IU_RSP)
+			--target->req_lim;
+	}
+
+	return ret;
+}
+
 static int srp_post_recv(struct srp_target_port *target)
 {
 	unsigned long flags;
@@ -822,7 +891,7 @@ static int srp_post_recv(struct srp_target_port *target)
 
 	spin_lock_irqsave(target->scsi_host->host_lock, flags);
 
-	next	 = target->rx_head & (SRP_RQ_SIZE - 1);
+	next	 = target->rx_head & SRP_RQ_MASK;
 	wr.wr_id = next;
 	iu	 = target->rx_ring[next];
 
@@ -896,6 +965,71 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
 	spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
 }
 
+static int srp_response_common(struct srp_target_port *target, s32 req_delta,
+			       void *rsp, int len)
+{
+	struct ib_device *dev;
+	unsigned long flags;
+	struct srp_iu *iu;
+	int err = 1;
+
+	dev = target->srp_host->srp_dev->dev;
+
+	spin_lock_irqsave(target->scsi_host->host_lock, flags);
+	target->req_lim += req_delta;
+
+	iu = __srp_get_tx_iu(target, SRP_IU_RSP);
+	if (!iu) {
+		shost_printk(KERN_ERR, target->scsi_host, PFX
+			     "no IU available to send response\n");
+		goto out;
+	}
+
+	ib_dma_sync_single_for_cpu(dev, iu->dma, len, DMA_TO_DEVICE);
+	memcpy(iu->buf, rsp, len);
+	ib_dma_sync_single_for_device(dev, iu->dma, len, DMA_TO_DEVICE);
+
+	err = __srp_post_send(target, iu, len);
+	if (err)
+		shost_printk(KERN_ERR, target->scsi_host, PFX
+			     "unable to post response: %d\n", err);
+
+out:
+	spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
+	return err;
+}
+
+static void srp_process_cred_req(struct srp_target_port *target,
+				 struct srp_cred_req *req)
+{
+	struct srp_cred_rsp rsp = {
+		.opcode = SRP_CRED_RSP,
+		.tag = req->tag,
+	};
+	s32 delta = be32_to_cpu(req->req_lim_delta);
+
+	if (srp_response_common(target, delta, &rsp, sizeof rsp))
+		shost_printk(KERN_ERR, target->scsi_host, PFX
+			     "problems processing SRP_CRED_REQ\n");
+}
+
+static void srp_process_aer_req(struct srp_target_port *target,
+				struct srp_aer_req *req)
+{
+	struct srp_aer_rsp rsp = {
+		.opcode = SRP_AER_RSP,
+		.tag = req->tag,
+	};
+	s32 delta = be32_to_cpu(req->req_lim_delta);
+
+	shost_printk(KERN_ERR, target->scsi_host, PFX
+		     "ignoring AER for LUN %llu\n", be64_to_cpu(req->lun));
+
+	if (srp_response_common(target, delta, &rsp, sizeof rsp))
+		shost_printk(KERN_ERR, target->scsi_host, PFX
+			     "problems processing SRP_AER_REQ\n");
+}
+
 static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
 {
 	struct ib_device *dev;
@@ -923,6 +1057,14 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
 		srp_process_rsp(target, iu->buf);
 		break;
 
+	case SRP_CRED_REQ:
+		srp_process_cred_req(target, iu->buf);
+		break;
+
+	case SRP_AER_REQ:
+		srp_process_aer_req(target, iu->buf);
+		break;
+
 	case SRP_T_LOGOUT:
 		/* XXX Handle target logout */
 		shost_printk(KERN_WARNING, target->scsi_host,
@@ -981,61 +1123,6 @@ static void srp_send_completion(struct ib_cq *cq, void *target_ptr)
 	}
 }
 
-/*
- * Must be called with target->scsi_host->host_lock held to protect
- * req_lim and tx_head.  Lock cannot be dropped between call here and
- * call to __srp_post_send().
- */
-static struct srp_iu *__srp_get_tx_iu(struct srp_target_port *target,
-					enum srp_request_type req_type)
-{
-	s32 min = (req_type == SRP_REQ_TASK_MGMT) ? 1 : 2;
-
-	srp_send_completion(target->send_cq, target);
-
-	if (target->tx_head - target->tx_tail >= SRP_SQ_SIZE)
-		return NULL;
-
-	if (target->req_lim < min) {
-		++target->zero_req_lim;
-		return NULL;
-	}
-
-	return target->tx_ring[target->tx_head & SRP_SQ_SIZE];
-}
-
-/*
- * Must be called with target->scsi_host->host_lock held to protect
- * req_lim and tx_head.
- */
-static int __srp_post_send(struct srp_target_port *target,
-			   struct srp_iu *iu, int len)
-{
-	struct ib_sge list;
-	struct ib_send_wr wr, *bad_wr;
-	int ret = 0;
-
-	list.addr   = iu->dma;
-	list.length = len;
-	list.lkey   = target->srp_host->srp_dev->mr->lkey;
-
-	wr.next       = NULL;
-	wr.wr_id      = target->tx_head & SRP_SQ_SIZE;
-	wr.sg_list    = &list;
-	wr.num_sge    = 1;
-	wr.opcode     = IB_WR_SEND;
-	wr.send_flags = IB_SEND_SIGNALED;
-
-	ret = ib_post_send(target->qp, &wr, &bad_wr);
-
-	if (!ret) {
-		++target->tx_head;
-		--target->req_lim;
-	}
-
-	return ret;
-}
-
 static int srp_queuecommand(struct scsi_cmnd *scmnd,
 			    void (*done)(struct scsi_cmnd *))
 {
@@ -1056,7 +1143,7 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
 		return 0;
 	}
 
-	iu = __srp_get_tx_iu(target, SRP_REQ_NORMAL);
+	iu = __srp_get_tx_iu(target, SRP_IU_CMD);
 	if (!iu)
 		goto err;
 
@@ -1064,7 +1151,7 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
 	ib_dma_sync_single_for_cpu(dev, iu->dma, srp_max_iu_len,
 				   DMA_TO_DEVICE);
 
-	req = list_entry(target->free_reqs.next, struct srp_request, list);
+	req = list_first_entry(&target->free_reqs, struct srp_request, list);
 
 	scmnd->scsi_done     = done;
 	scmnd->result        = 0;
@@ -1121,7 +1208,7 @@ static int srp_alloc_iu_bufs(struct srp_target_port *target)
 			goto err;
 	}
 
-	for (i = 0; i < SRP_SQ_SIZE + 1; ++i) {
+	for (i = 0; i < SRP_SQ_SIZE; ++i) {
 		target->tx_ring[i] = srp_alloc_iu(target->srp_host,
 						  srp_max_iu_len,
 						  GFP_KERNEL, DMA_TO_DEVICE);
@@ -1137,7 +1224,7 @@ err:
 		target->rx_ring[i] = NULL;
 	}
 
-	for (i = 0; i < SRP_SQ_SIZE + 1; ++i) {
+	for (i = 0; i < SRP_SQ_SIZE; ++i) {
 		srp_free_iu(target->srp_host, target->tx_ring[i]);
 		target->tx_ring[i] = NULL;
 	}
@@ -1252,8 +1339,13 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
 			target->max_ti_iu_len = be32_to_cpu(rsp->max_ti_iu_len);
 			target->req_lim       = be32_to_cpu(rsp->req_lim_delta);
 
-			target->scsi_host->can_queue = min(target->req_lim,
-							   target->scsi_host->can_queue);
+			/*
+			 * Reserve credits for task management so we don't
+			 * bounce requests back to the SCSI mid-layer.
+			 */
+			target->scsi_host->can_queue
+				= min(target->req_lim - SRP_TSK_MGMT_SQ_SIZE,
+				      target->scsi_host->can_queue);
 		} else {
 			shost_printk(KERN_WARNING, target->scsi_host,
 				    PFX "Unhandled RSP opcode %#x\n", opcode);
@@ -1350,6 +1442,7 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
 static int srp_send_tsk_mgmt(struct srp_target_port *target,
 			     struct srp_request *req, u8 func)
 {
+	struct ib_device *dev = target->srp_host->srp_dev->dev;
 	struct srp_iu *iu;
 	struct srp_tsk_mgmt *tsk_mgmt;
 
@@ -1363,10 +1456,12 @@ static int srp_send_tsk_mgmt(struct srp_target_port *target,
 
 	init_completion(&req->done);
 
-	iu = __srp_get_tx_iu(target, SRP_REQ_TASK_MGMT);
+	iu = __srp_get_tx_iu(target, SRP_IU_TSK_MGMT);
 	if (!iu)
 		goto out;
 
+	ib_dma_sync_single_for_cpu(dev, iu->dma, sizeof *tsk_mgmt,
+				   DMA_TO_DEVICE);
 	tsk_mgmt = iu->buf;
 	memset(tsk_mgmt, 0, sizeof *tsk_mgmt);
 
@@ -1376,6 +1471,8 @@ static int srp_send_tsk_mgmt(struct srp_target_port *target,
 	tsk_mgmt->tsk_mgmt_func = func;
 	tsk_mgmt->task_tag 	= req->index;
 
+	ib_dma_sync_single_for_device(dev, iu->dma, sizeof *tsk_mgmt,
+				      DMA_TO_DEVICE);
 	if (__srp_post_send(target, iu, sizeof *tsk_mgmt))
 		goto out;
 
@@ -1626,9 +1723,9 @@ static struct scsi_host_template srp_template = {
 	.eh_abort_handler		= srp_abort,
 	.eh_device_reset_handler	= srp_reset_device,
 	.eh_host_reset_handler		= srp_reset_host,
-	.can_queue			= SRP_SQ_SIZE,
+	.can_queue			= SRP_CMD_SQ_SIZE,
 	.this_id			= -1,
-	.cmd_per_lun			= SRP_SQ_SIZE,
+	.cmd_per_lun			= SRP_CMD_SQ_SIZE,
 	.use_clustering			= ENABLE_CLUSTERING,
 	.shost_attrs			= srp_host_attrs
 };
@@ -1813,7 +1910,7 @@ static int srp_parse_options(const char *buf, struct srp_target_port *target)
 				printk(KERN_WARNING PFX "bad max cmd_per_lun parameter '%s'\n", p);
 				goto out;
 			}
-			target->scsi_host->cmd_per_lun = min(token, SRP_SQ_SIZE);
+			target->scsi_host->cmd_per_lun = min(token, SRP_CMD_SQ_SIZE);
 			break;
 
 		case SRP_OPT_IO_CLASS:
@@ -1891,7 +1988,7 @@ static ssize_t srp_create_target(struct device *dev,
 
 	INIT_LIST_HEAD(&target->free_reqs);
 	INIT_LIST_HEAD(&target->req_queue);
-	for (i = 0; i < SRP_SQ_SIZE; ++i) {
+	for (i = 0; i < SRP_CMD_SQ_SIZE; ++i) {
 		target->req_ring[i].index = i;
 		list_add_tail(&target->req_ring[i].list, &target->free_reqs);
 	}
@@ -2159,6 +2256,9 @@ static int __init srp_init_module(void)
 {
 	int ret;
 
+	BUILD_BUG_ON_NOT_POWER_OF_2(SRP_SQ_SIZE);
+	BUILD_BUG_ON_NOT_POWER_OF_2(SRP_RQ_SIZE);
+
 	if (srp_sg_tablesize > 255) {
 		printk(KERN_WARNING PFX "Clamping srp_sg_tablesize to 255\n");
 		srp_sg_tablesize = 255;
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index 5a80eac6fda..ed0dce9e479 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -59,7 +59,14 @@ enum {
 
 	SRP_RQ_SHIFT    	= 6,
 	SRP_RQ_SIZE		= 1 << SRP_RQ_SHIFT,
-	SRP_SQ_SIZE		= SRP_RQ_SIZE - 1,
+	SRP_RQ_MASK		= SRP_RQ_SIZE - 1,
+
+	SRP_SQ_SIZE		= SRP_RQ_SIZE,
+	SRP_SQ_MASK		= SRP_SQ_SIZE - 1,
+	SRP_RSP_SQ_SIZE		= 1,
+	SRP_REQ_SQ_SIZE		= SRP_SQ_SIZE - SRP_RSP_SQ_SIZE,
+	SRP_TSK_MGMT_SQ_SIZE	= 1,
+	SRP_CMD_SQ_SIZE		= SRP_REQ_SQ_SIZE - SRP_TSK_MGMT_SQ_SIZE,
 
 	SRP_TAG_TSK_MGMT	= 1 << (SRP_RQ_SHIFT + 1),
 
@@ -75,9 +82,10 @@ enum srp_target_state {
 	SRP_TARGET_REMOVED
 };
 
-enum srp_request_type {
-	SRP_REQ_NORMAL,
-	SRP_REQ_TASK_MGMT,
+enum srp_iu_type {
+	SRP_IU_CMD,
+	SRP_IU_TSK_MGMT,
+	SRP_IU_RSP,
 };
 
 struct srp_device {
@@ -144,11 +152,11 @@ struct srp_target_port {
 
 	unsigned		tx_head;
 	unsigned		tx_tail;
-	struct srp_iu	       *tx_ring[SRP_SQ_SIZE + 1];
+	struct srp_iu	       *tx_ring[SRP_SQ_SIZE];
 
 	struct list_head	free_reqs;
 	struct list_head	req_queue;
-	struct srp_request	req_ring[SRP_SQ_SIZE];
+	struct srp_request	req_ring[SRP_CMD_SQ_SIZE];
 
 	struct work_struct	work;
 
@@ -164,6 +172,7 @@ struct srp_iu {
 	void		       *buf;
 	size_t			size;
 	enum dma_data_direction	direction;
+	enum srp_iu_type	type;
 };
 
 #endif /* IB_SRP_H */