[PATCH v3 17/18] ibmvfc: provide modules parameters for MQ settings

[Tyrel Datwyler <tyreld@linux.ibm.com>]

Add the various module parameter toggles for adjusting the MQ
characteristics at boot/load time as well as a device attribute for
changing the client scsi channel request amount.

Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
---
 drivers/scsi/ibmvscsi/ibmvfc.c | 76 +++++++++++++++++++++++++++++-----
 1 file changed, 66 insertions(+), 10 deletions(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index e353b9e88104..e499599662ec 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -40,6 +40,12 @@ static unsigned int disc_threads = IBMVFC_MAX_DISC_THREADS;
 static unsigned int ibmvfc_debug = IBMVFC_DEBUG;
 static unsigned int log_level = IBMVFC_DEFAULT_LOG_LEVEL;
 static unsigned int cls3_error = IBMVFC_CLS3_ERROR;
+static unsigned int mq_enabled = IBMVFC_MQ;
+static unsigned int nr_scsi_hw_queues = IBMVFC_SCSI_HW_QUEUES;
+static unsigned int nr_scsi_channels = IBMVFC_SCSI_CHANNELS;
+static unsigned int mig_channels_only = IBMVFC_MIG_NO_SUB_TO_CRQ;
+static unsigned int mig_no_less_channels = IBMVFC_MIG_NO_N_TO_M;
+
 static LIST_HEAD(ibmvfc_head);
 static DEFINE_SPINLOCK(ibmvfc_driver_lock);
 static struct scsi_transport_template *ibmvfc_transport_template;
@@ -49,6 +55,22 @@ MODULE_AUTHOR("Brian King <brking@linux.vnet.ibm.com>");
 MODULE_LICENSE("GPL");
 MODULE_VERSION(IBMVFC_DRIVER_VERSION);
 
+module_param_named(mq, mq_enabled, uint, S_IRUGO);
+MODULE_PARM_DESC(mq, "Enable multiqueue support. "
+		 "[Default=" __stringify(IBMVFC_MQ) "]");
+module_param_named(scsi_host_queues, nr_scsi_hw_queues, uint, S_IRUGO);
+MODULE_PARM_DESC(scsi_host_queues, "Number of SCSI Host submission queues. "
+		 "[Default=" __stringify(IBMVFC_SCSI_HW_QUEUES) "]");
+module_param_named(scsi_hw_channels, nr_scsi_channels, uint, S_IRUGO);
+MODULE_PARM_DESC(scsi_hw_channels, "Number of hw scsi channels to request. "
+		 "[Default=" __stringify(IBMVFC_SCSI_CHANNELS) "]");
+module_param_named(mig_channels_only, mig_channels_only, uint, S_IRUGO);
+MODULE_PARM_DESC(mig_channels_only, "Prevent migration to non-channelized system. "
+		 "[Default=" __stringify(IBMVFC_MIG_NO_SUB_TO_CRQ) "]");
+module_param_named(mig_no_less_channels, mig_no_less_channels, uint, S_IRUGO);
+MODULE_PARM_DESC(mig_no_less_channels, "Prevent migration to system with less channels. "
+		 "[Default=" __stringify(IBMVFC_MIG_NO_N_TO_M) "]");
+
 module_param_named(init_timeout, init_timeout, uint, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(init_timeout, "Initialization timeout in seconds. "
 		 "[Default=" __stringify(IBMVFC_INIT_TIMEOUT) "]");
@@ -823,7 +845,7 @@ static int ibmvfc_reset_crq(struct ibmvfc_host *vhost)
 	crq->cur = 0;
 
 	if (vhost->scsi_scrqs.scrqs) {
-		for (i = 0; i < IBMVFC_SCSI_HW_QUEUES; i++) {
+		for (i = 0; i < nr_scsi_hw_queues; i++) {
 			scrq = &vhost->scsi_scrqs.scrqs[i];
 			memset(scrq->msgs, 0, PAGE_SIZE);
 			scrq->cur = 0;
@@ -3234,6 +3256,37 @@ static ssize_t ibmvfc_store_log_level(struct device *dev,
 	return strlen(buf);
 }
 
+static ssize_t ibmvfc_show_scsi_channels(struct device *dev,
+					 struct device_attribute *attr, char *buf)
+{
+	struct Scsi_Host *shost = class_to_shost(dev);
+	struct ibmvfc_host *vhost = shost_priv(shost);
+	unsigned long flags = 0;
+	int len;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	len = snprintf(buf, PAGE_SIZE, "%d\n", vhost->client_scsi_channels);
+	spin_unlock_irqrestore(shost->host_lock, flags);
+	return len;
+}
+
+static ssize_t ibmvfc_store_scsi_channels(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t count)
+{
+	struct Scsi_Host *shost = class_to_shost(dev);
+	struct ibmvfc_host *vhost = shost_priv(shost);
+	unsigned long flags = 0;
+	unsigned int channels;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	channels = simple_strtoul(buf, NULL, 10);
+	vhost->client_scsi_channels = min(channels, nr_scsi_hw_queues);
+	ibmvfc_hard_reset_host(vhost);
+	spin_unlock_irqrestore(shost->host_lock, flags);
+	return strlen(buf);
+}
+
 static DEVICE_ATTR(partition_name, S_IRUGO, ibmvfc_show_host_partition_name, NULL);
 static DEVICE_ATTR(device_name, S_IRUGO, ibmvfc_show_host_device_name, NULL);
 static DEVICE_ATTR(port_loc_code, S_IRUGO, ibmvfc_show_host_loc_code, NULL);
@@ -3242,6 +3295,8 @@ static DEVICE_ATTR(npiv_version, S_IRUGO, ibmvfc_show_host_npiv_version, NULL);
 static DEVICE_ATTR(capabilities, S_IRUGO, ibmvfc_show_host_capabilities, NULL);
 static DEVICE_ATTR(log_level, S_IRUGO | S_IWUSR,
 		   ibmvfc_show_log_level, ibmvfc_store_log_level);
+static DEVICE_ATTR(nr_scsi_channels, S_IRUGO | S_IWUSR,
+		   ibmvfc_show_scsi_channels, ibmvfc_store_scsi_channels);
 
 #ifdef CONFIG_SCSI_IBMVFC_TRACE
 /**
@@ -3298,6 +3353,7 @@ static struct device_attribute *ibmvfc_attrs[] = {
 	&dev_attr_npiv_version,
 	&dev_attr_capabilities,
 	&dev_attr_log_level,
+	&dev_attr_nr_scsi_channels,
 	NULL
 };
 
@@ -4685,9 +4741,9 @@ static void ibmvfc_channel_enquiry(struct ibmvfc_host *vhost)
 	mad->common.opcode = cpu_to_be32(IBMVFC_CHANNEL_ENQUIRY);
 	mad->common.length = cpu_to_be16(sizeof(*mad));
 
-	if (IBMVFC_MIG_NO_SUB_TO_CRQ)
+	if (mig_channels_only)
 		mad->flags |= cpu_to_be32(IBMVFC_NO_CHANNELS_TO_CRQ_SUPPORT);
-	if (IBMVFC_MIG_NO_N_TO_M)
+	if (mig_no_less_channels)
 		mad->flags |= cpu_to_be32(IBMVFC_NO_N_TO_M_CHANNELS_SUPPORT);
 
 	ibmvfc_set_host_action(vhost, IBMVFC_HOST_ACTION_INIT_WAIT);
@@ -5426,13 +5482,13 @@ static int ibmvfc_init_sub_crqs(struct ibmvfc_host *vhost)
 
 	ENTER;
 
-	vhost->scsi_scrqs.scrqs = kcalloc(IBMVFC_SCSI_HW_QUEUES,
+	vhost->scsi_scrqs.scrqs = kcalloc(nr_scsi_hw_queues,
 					  sizeof(*vhost->scsi_scrqs.scrqs),
 					  GFP_KERNEL);
 	if (!vhost->scsi_scrqs.scrqs)
 		return -1;
 
-	for (i = 0; i < IBMVFC_SCSI_HW_QUEUES; i++) {
+	for (i = 0; i < nr_scsi_hw_queues; i++) {
 		if (ibmvfc_register_scsi_channel(vhost, i)) {
 			for (j = i; j > 0; j--)
 				ibmvfc_deregister_scsi_channel(vhost, j - 1);
@@ -5456,7 +5512,7 @@ static void ibmvfc_release_sub_crqs(struct ibmvfc_host *vhost)
 	if (!vhost->scsi_scrqs.scrqs)
 		return;
 
-	for (i = 0; i < IBMVFC_SCSI_HW_QUEUES; i++)
+	for (i = 0; i < nr_scsi_hw_queues; i++)
 		ibmvfc_deregister_scsi_channel(vhost, i);
 
 	kfree(vhost->scsi_scrqs.scrqs);
@@ -5668,13 +5724,13 @@ static int ibmvfc_probe(struct vio_dev *vdev, const struct vio_device_id *id)
 	}
 
 	shost->transportt = ibmvfc_transport_template;
-	shost->can_queue = (max_requests / IBMVFC_SCSI_HW_QUEUES);
+	shost->can_queue = (max_requests / nr_scsi_hw_queues);
 	shost->max_lun = max_lun;
 	shost->max_id = max_targets;
 	shost->max_sectors = IBMVFC_MAX_SECTORS;
 	shost->max_cmd_len = IBMVFC_MAX_CDB_LEN;
 	shost->unique_id = shost->host_no;
-	shost->nr_hw_queues = IBMVFC_SCSI_HW_QUEUES;
+	shost->nr_hw_queues = nr_scsi_hw_queues;
 
 	vhost = shost_priv(shost);
 	INIT_LIST_HEAD(&vhost->sent);
@@ -5687,8 +5743,8 @@ static int ibmvfc_probe(struct vio_dev *vdev, const struct vio_device_id *id)
 	vhost->log_level = log_level;
 	vhost->task_set = 1;
 
-	vhost->mq_enabled = IBMVFC_MQ;
-	vhost->client_scsi_channels = IBMVFC_SCSI_CHANNELS;
+	vhost->mq_enabled = mq_enabled;
+	vhost->client_scsi_channels = min(nr_scsi_hw_queues, nr_scsi_channels);
 	vhost->using_channels = 0;
 	vhost->do_enquiry = 1;
 
-- 
2.27.0