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Commit c996bb47 authored by Bart Van Assche's avatar Bart Van Assche Committed by Roland Dreier
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IB/srp: Make receive buffer handling more robust 



The current strategy in ib_srp for posting receive buffers is:

 * Post one buffer after channel establishment.
 * Post one buffer before sending an SRP_CMD or SRP_TSK_MGMT to the target.

As a result, only the first non-SRP_RSP information unit from the
target will be processed.  If that first information unit is an
SRP_T_LOGOUT, it will be processed.  On the other hand, if the
initiator receives an SRP_CRED_REQ or SRP_AER_REQ before it receives a
SRP_T_LOGOUT, the SRP_T_LOGOUT won't be processed.

We can fix this inconsistency by changing the strategy for posting
receive buffers to:

 * Post all receive buffers after channel establishment.
 * After a receive buffer has been consumed and processed, post it again.

A side effect is that the ib_post_recv() call is moved out of the SCSI
command processing path.  Since __srp_post_recv() is not called
directly any more, get rid of it and move the code directly into
srp_post_recv().  Also, move srp_post_recv() up in the file to avoid a
forward declaration.

Signed-off-by: default avatarBart Van Assche <bart.vanassche@gmail.com>
Acked-by: default avatarDavid Dillow <dave@thedillows.org>
Signed-off-by: default avatarRoland Dreier <rolandd@cisco.com>
parent 7a700811

drivers/infiniband/ulp/srp/ib_srp.c

+44 −45
Original line number Diff line number Diff line
@@ -811,6 +811,38 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target, 
	return len;

}



static int srp_post_recv(struct srp_target_port *target)

{

	unsigned long flags;

	struct srp_iu *iu;

	struct ib_sge list;

	struct ib_recv_wr wr, *bad_wr;

	unsigned int next;

	int ret;



	spin_lock_irqsave(target->scsi_host->host_lock, flags);



	next	 = target->rx_head & (SRP_RQ_SIZE - 1);

	wr.wr_id = next;

	iu	 = target->rx_ring[next];



	list.addr   = iu->dma;

	list.length = iu->size;

	list.lkey   = target->srp_host->srp_dev->mr->lkey;



	wr.next     = NULL;

	wr.sg_list  = &list;

	wr.num_sge  = 1;



	ret = ib_post_recv(target->qp, &wr, &bad_wr);

	if (!ret)

		++target->rx_head;



	spin_unlock_irqrestore(target->scsi_host->host_lock, flags);



	return ret;

}



static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)

{

	struct srp_request *req;
@@ -868,6 +900,7 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc) 
{

	struct ib_device *dev;

	struct srp_iu *iu;

	int res;

	u8 opcode;



	iu = target->rx_ring[wc->wr_id];
@@ -904,6 +937,11 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc) 


	ib_dma_sync_single_for_device(dev, iu->dma, target->max_ti_iu_len,

				      DMA_FROM_DEVICE);



	res = srp_post_recv(target);

	if (res != 0)

		shost_printk(KERN_ERR, target->scsi_host,

			     PFX "Recv failed with error code %d\n", res);

}



static void srp_recv_completion(struct ib_cq *cq, void *target_ptr)
@@ -943,45 +981,6 @@ static void srp_send_completion(struct ib_cq *cq, void *target_ptr) 
	}

}



static int __srp_post_recv(struct srp_target_port *target)

{

	struct srp_iu *iu;

	struct ib_sge list;

	struct ib_recv_wr wr, *bad_wr;

	unsigned int next;

	int ret;



	next 	 = target->rx_head & (SRP_RQ_SIZE - 1);

	wr.wr_id = next;

	iu 	 = target->rx_ring[next];



	list.addr   = iu->dma;

	list.length = iu->size;

	list.lkey   = target->srp_host->srp_dev->mr->lkey;



	wr.next     = NULL;

	wr.sg_list  = &list;

	wr.num_sge  = 1;



	ret = ib_post_recv(target->qp, &wr, &bad_wr);

	if (!ret)

		++target->rx_head;



	return ret;

}



static int srp_post_recv(struct srp_target_port *target)

{

	unsigned long flags;

	int ret;



	spin_lock_irqsave(target->scsi_host->host_lock, flags);

	ret = __srp_post_recv(target);

	spin_unlock_irqrestore(target->scsi_host->host_lock, flags);



	return ret;

}



/*

 * 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
@@ -1091,11 +1090,6 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd, 
		goto err;

	}



	if (__srp_post_recv(target)) {

		shost_printk(KERN_ERR, target->scsi_host, PFX "Recv failed\n");

		goto err_unmap;

	}



	ib_dma_sync_single_for_device(dev, iu->dma, srp_max_iu_len,

				      DMA_TO_DEVICE);
@@ -1238,6 +1232,7 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event) 
	int attr_mask = 0;

	int comp = 0;

	int opcode = 0;

	int i;



	switch (event->event) {

	case IB_CM_REQ_ERROR:
@@ -1287,9 +1282,13 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event) 
		if (target->status)

			break;



		for (i = 0; i < SRP_RQ_SIZE; i++) {

			target->status = srp_post_recv(target);

			if (target->status)

				break;

		}

		if (target->status)

			break;



		qp_attr->qp_state = IB_QPS_RTS;

		target->status = ib_cm_init_qp_attr(cm_id, qp_attr, &attr_mask);