scsi: qla2xxx: Add debug knob for user control workload

For Target mode, user can control the work load by placing qla2xxx's irq
vector on certain CPU via the smp_affinity knob. This patch allows user
to control the number of QPair's irq to be active. The irqs are
allocated at driver load time until unload. The work itself is placed on
the QPair based on user setting.

Usage:
  modprobe qla2xxx qlini_mode=disabled ql2xuctrlirq=1
  mount -t debugfs none /sys/kernel/debug
  echo 2 > /sys/kernel/debug/qla2xxx/qla2xxx_[host num]/naqp
  echo [cpu id] > /proc/irq/[irq id]/smp_affinity_list

Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 89 insertions, 0 deletions

diff --git a/drivers/scsi/qla2xxx/qla_dfs.c b/drivers/scsi/qla2xxx/qla_dfs.c
index 391c50be2297..63d7374dce77 100644
--- a/drivers/scsi/qla2xxx/qla_dfs.c
+++ b/drivers/scsi/qla2xxx/qla_dfs.c
@@ -314,6 +314,81 @@ static const struct file_operations dfs_fce_ops = {
 	.release	= qla2x00_dfs_fce_release,
 };
 
+static int
+qla_dfs_naqp_show(struct seq_file *s, void *unused)
+{
+	struct scsi_qla_host *vha = s->private;
+	struct qla_hw_data *ha = vha->hw;
+
+	seq_printf(s, "%d\n", ha->tgt.num_act_qpairs);
+	return 0;
+}
+
+static int
+qla_dfs_naqp_open(struct inode *inode, struct file *file)
+{
+	struct scsi_qla_host *vha = inode->i_private;
+
+	return single_open(file, qla_dfs_naqp_show, vha);
+}
+
+static ssize_t
+qla_dfs_naqp_write(struct file *file, const char __user *buffer,
+    size_t count, loff_t *pos)
+{
+	struct seq_file *s = file->private_data;
+	struct scsi_qla_host *vha = s->private;
+	struct qla_hw_data *ha = vha->hw;
+	char *buf;
+	int rc = 0;
+	unsigned long num_act_qp;
+
+	if (!(IS_QLA27XX(ha) || IS_QLA83XX(ha))) {
+		pr_err("host%ld: this adapter does not support Multi Q.",
+		    vha->host_no);
+		return -EINVAL;
+	}
+
+	if (!vha->flags.qpairs_available) {
+		pr_err("host%ld: Driver is not setup with Multi Q.",
+		    vha->host_no);
+		return -EINVAL;
+	}
+	buf = memdup_user_nul(buffer, count);
+	if (IS_ERR(buf)) {
+		pr_err("host%ld: fail to copy user buffer.",
+		    vha->host_no);
+		return PTR_ERR(buf);
+	}
+
+	num_act_qp = simple_strtoul(buf, NULL, 0);
+
+	if (num_act_qp >= vha->hw->max_qpairs) {
+		pr_err("User set invalid number of qpairs %lu. Max = %d",
+		    num_act_qp, vha->hw->max_qpairs);
+		rc = -EINVAL;
+		goto out_free;
+	}
+
+	if (num_act_qp != ha->tgt.num_act_qpairs) {
+		ha->tgt.num_act_qpairs = num_act_qp;
+		qlt_clr_qp_table(vha);
+	}
+	rc = count;
+out_free:
+	kfree(buf);
+	return rc;
+}
+
+static const struct file_operations dfs_naqp_ops = {
+	.open		= qla_dfs_naqp_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+	.write		= qla_dfs_naqp_write,
+};
+
+
 int
 qla2x00_dfs_setup(scsi_qla_host_t *vha)
 {
@@ -391,6 +466,15 @@ create_nodes:
 		goto out;
 	}
 
+	if (IS_QLA27XX(ha) || IS_QLA83XX(ha)) {
+		ha->tgt.dfs_naqp = debugfs_create_file("naqp",
+		    0400, ha->dfs_dir, vha, &dfs_naqp_ops);
+		if (!ha->tgt.dfs_naqp) {
+			ql_log(ql_log_warn, vha, 0xd011,
+			    "Unable to create debugFS naqp node.\n");
+			goto out;
+		}
+	}
 out:
 	return 0;
 }
@@ -400,6 +484,11 @@ qla2x00_dfs_remove(scsi_qla_host_t *vha)
 {
 	struct qla_hw_data *ha = vha->hw;
 
+	if (ha->tgt.dfs_naqp) {
+		debugfs_remove(ha->tgt.dfs_naqp);
+		ha->tgt.dfs_naqp = NULL;
+	}
+
 	if (ha->tgt.dfs_tgt_sess) {
 		debugfs_remove(ha->tgt.dfs_tgt_sess);
 		ha->tgt.dfs_tgt_sess = NULL;