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Commit a897ff2a authored by Robert Jennings's avatar Robert Jennings Committed by James Bottomley
Browse files

[SCSI] ibmvscsi: allow for dynamic adjustment of server request_limit 



The request limit calculations used previously on the client failed to
mirror the state of the server.  Additionally, when a value < 3 was provided
there could be problems setting can_queue and handling abort and reset
commands.

Signed-off-by: default avatar"Robert Jennings" <rcj@linux.vnet.ibm.com>
Signed-off-by: default avatarSantiago Leon <santil@us.ibm.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@SteelEye.com>
parent a45c863f

drivers/scsi/ibmvscsi/ibmvscsi.c

+38 −20
Original line number Diff line number Diff line
@@ -85,7 +85,7 @@ 
static int max_id = 64;

static int max_channel = 3;

static int init_timeout = 5;

static int max_requests = 50;

static int max_requests = IBMVSCSI_MAX_REQUESTS_DEFAULT;



#define IBMVSCSI_VERSION "1.5.8"
@@ -538,7 +538,8 @@ static int ibmvscsi_send_srp_event(struct srp_event_struct *evt_struct, 
	int request_status;

	int rc;



	/* If we have exhausted our request limit, just fail this request.

	/* If we have exhausted our request limit, just fail this request,

	 * unless it is for a reset or abort.

	 * Note that there are rare cases involving driver generated requests 

	 * (such as task management requests) that the mid layer may think we

	 * can handle more requests (can_queue) when we actually can't
@@ -551,10 +552,31 @@ static int ibmvscsi_send_srp_event(struct srp_event_struct *evt_struct, 
		 */

		if (request_status < -1)

			goto send_error;

		/* Otherwise, if we have run out of requests */

		else if (request_status < 0)

		/* Otherwise, we may have run out of requests. */

		/* Abort and reset calls should make it through.

		 * Nothing except abort and reset should use the last two

		 * slots unless we had two or less to begin with.

		 */

		else if (request_status < 2 &&

		         evt_struct->iu.srp.cmd.opcode != SRP_TSK_MGMT) {

			/* In the case that we have less than two requests

			 * available, check the server limit as a combination

			 * of the request limit and the number of requests

			 * in-flight (the size of the send list).  If the

			 * server limit is greater than 2, return busy so

			 * that the last two are reserved for reset and abort.

			 */

			int server_limit = request_status;

			struct srp_event_struct *tmp_evt;



			list_for_each_entry(tmp_evt, &hostdata->sent, list) {

				server_limit++;

			}



			if (server_limit > 2)

				goto send_busy;

		}

	}



	/* Copy the IU into the transfer area */

	*evt_struct->xfer_iu = evt_struct->iu;
@@ -572,6 +594,7 @@ static int ibmvscsi_send_srp_event(struct srp_event_struct *evt_struct, 


		printk(KERN_ERR "ibmvscsi: send error %d\n",

		       rc);

		atomic_inc(&hostdata->request_limit);

		goto send_error;

	}
@@ -581,6 +604,7 @@ static int ibmvscsi_send_srp_event(struct srp_event_struct *evt_struct, 
	unmap_cmd_data(&evt_struct->iu.srp.cmd, evt_struct, hostdata->dev);



	free_event_struct(&hostdata->pool, evt_struct);

	atomic_inc(&hostdata->request_limit);

	return SCSI_MLQUEUE_HOST_BUSY;



 send_error:
@@ -831,23 +855,16 @@ static void login_rsp(struct srp_event_struct *evt_struct) 


	printk(KERN_INFO "ibmvscsi: SRP_LOGIN succeeded\n");



	if (evt_struct->xfer_iu->srp.login_rsp.req_lim_delta >

	    (max_requests - 2))

		evt_struct->xfer_iu->srp.login_rsp.req_lim_delta =

		    max_requests - 2;

	if (evt_struct->xfer_iu->srp.login_rsp.req_lim_delta < 0)

		printk(KERN_ERR "ibmvscsi: Invalid request_limit.\n");



	/* Now we know what the real request-limit is */

	/* Now we know what the real request-limit is.

	 * This value is set rather than added to request_limit because

	 * request_limit could have been set to -1 by this client.

	 */

	atomic_set(&hostdata->request_limit,

		   evt_struct->xfer_iu->srp.login_rsp.req_lim_delta);



	hostdata->host->can_queue =

	    evt_struct->xfer_iu->srp.login_rsp.req_lim_delta - 2;



	if (hostdata->host->can_queue < 1) {

		printk(KERN_ERR "ibmvscsi: Invalid request_limit_delta\n");

		return;

	}



	/* If we had any pending I/Os, kick them */

	scsi_unblock_requests(hostdata->host);
@@ -1483,7 +1500,7 @@ static struct scsi_host_template driver_template = { 
	.eh_abort_handler = ibmvscsi_eh_abort_handler,

	.eh_device_reset_handler = ibmvscsi_eh_device_reset_handler,

	.cmd_per_lun = 16,

	.can_queue = 1,		/* Updated after SRP_LOGIN */

	.can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,

	.this_id = -1,

	.sg_tablesize = SG_ALL,

	.use_clustering = ENABLE_CLUSTERING,
@@ -1503,6 +1520,7 @@ static int ibmvscsi_probe(struct vio_dev *vdev, const struct vio_device_id *id) 


	vdev->dev.driver_data = NULL;



	driver_template.can_queue = max_requests;

	host = scsi_host_alloc(&driver_template, sizeof(*hostdata));

	if (!host) {

		printk(KERN_ERR "ibmvscsi: couldn't allocate host data\n");

drivers/scsi/ibmvscsi/ibmvscsi.h

+2 −0
Original line number Diff line number Diff line
@@ -44,6 +44,8 @@ struct Scsi_Host; 
 */

#define MAX_INDIRECT_BUFS 10



#define IBMVSCSI_MAX_REQUESTS_DEFAULT 100



/* ------------------------------------------------------------

 * Data Structures

 */