Cannot create queue pair with ib_create_qp
<p>I am writing an RDMA (InfiniBand) kernel module.</p>

<p>Up to now I have been successful creating the protection domain, completion queues for send and receive queues.</p>

<p>But whenever I try to create the Queue Pair by invoking ib_create_qp, it is failing to create the queue pair. The code which I'm wrote is shown below:</p>

<pre><code>#include &lt;linux/kernel.h&gt;
#include &lt;linux/init.h&gt;
#include &lt;linux/module.h&gt;
#include &lt;linux/list.h&gt;
#include &lt;linux/module.h&gt;
#include &lt;linux/err.h&gt;
#include "myClient.h"


struct workqueue_struct *myClient_workqueue;
struct ib_sa_client myClient_sa_client;
/*
static void myClient_add_one(struct ib_device *device);
static void myClient_remove_one(struct ib_device *device);
*/

struct ib_pd *mypd;
struct ib_cq *myrcvcq;
struct ib_cq *myClientsendcq;
struct ib_qp *myClientqp;

void myClient_ib_recvcompletion(struct ib_cq *cq)
{
    printk("A user-specified callback that is invoked when a completion event occurs on the CQ.\n");
}


void myClient_ib_sendcompletion(struct ib_cq *cq)
{
        printk("A user-specified callback that is invoked when a completion event occurs on the CQ.\n");
}
static void my_qp_event_handler(struct ib_event *myqpAsyncEvent, void *anyPointer)
{
        printk(KERN_INFO "Dummy affiliated asynchronous event occured function called \n");
}


static void myClient_add_one(struct ib_device *device)
{
    union ib_gid tmp_gid;
    int ret;
    int hcaport = 1;
    int result = -ENOMEM;
    u16 port1Pkey;
    struct ib_port_attr attr;

        ret = ib_query_port(device,hcaport,&amp;attr);
        printk("ib query port result %d  \n", ret);

//  Creating the Protection Domain for RDMA
    mypd = ib_alloc_pd(device);

    if(IS_ERR(mypd)){
        printk(KERN_INFO "Failed to allocate PD\n");
        return;
    }
    else{
        printk(KERN_INFO "1Successfully allocated the PD\n");
        pdset = true;
    }

//  Creating the receive completion queue for RDMA
    myrcvcq = ib_create_cq(device,myClient_ib_recvcompletion,NULL,NULL,myClient_recvq_size,0);
        if(IS_ERR(myrcvcq)){
                pr_err("%s:%d error code for receive cq%d\n", __func__, __LINE__, PTR_ERR(myrcvcq));
                //printk("Error creating QP: %d \n",PTR_ERR(myClientqp));
        }
    else{
        printk("Recieve CQ successfully created in address: %x \n",myrcvcq);
    }

//  Creating the send completion queue for RDMA
    myClientsendcq = ib_create_cq(device,myClient_ib_sendcompletion, NULL, NULL,myClient_sendq_size,0 );
        if(IS_ERR(myClientsendcq)){
                pr_err("%s:%d scqerror code for send cq%d\n", __func__, __LINE__, PTR_ERR(myClientsendcq));
                //printk("Error creating QP: %d \n",PTR_ERR(myClientqp));
        }
        else{
                printk("1Send CQ successfully created in address: %x \n",myClientsendcq);
        }

//  Creating the queue pair
//      Creating the queue pair

        struct ib_qp_init_attr init_qpattr;

        memset(&amp;init_qpattr,0,sizeof(init_qpattr));
        init_qpattr.event_handler = myClient_qp_event_handler;
        init_qpattr.cap.max_send_wr = 2;
        init_qpattr.cap.max_recv_wr = 2;
        init_qpattr.cap.max_recv_sge = 1;
        init_qpattr.cap.max_send_sge = 1;
        init_qpattr.sq_sig_type = IB_SIGNAL_ALL_WR;
        init_qpattr.qp_type = IB_QPT_UD;
        init_qpattr.send_cq = myClientsendcq;
        init_qpattr.recv_cq = myrcvcq;

        myClientqp = ib_create_qp(mypd,&amp;init_qpattr);

        if(IS_ERR(myClientqp)){
                pr_err("%s:%d error code %d\n", __func__, __LINE__, PTR_ERR(myClientqp));
                //printk("Error creating QP: %d \n",PTR_ERR(myClientqp));
        }
        else{
                printk(KERN_INFO "1The queue pair is successfully created \n");
                qpcreated = true;
        }



}
static void myClient_remove_one(struct ib_device *device)
{
}

static struct ib_client my_client = {
        .name   = "myRDMAclient",
        .add    = myClient_add_one,
        .remove = myClient_remove_one
};


static int __init myRDMAclient_init(void)
{
    int ret;

    ret = ib_register_client(&amp;my_client);
    if(ret){
        //printk(KERN_ALERT "KERN_ERR Failed to register IB client\n");
        goto err_sa;
    }
    printk(KERN_ALERT "lKERN_INFO Successfully registered myRDMAclient module \n");
    return 0;

err_sa:


    return ret;
}


module_init(myRDMAclient_init);
</code></pre>

<p>Here all the queries works except the <code>ib_create_qp(mypd,&amp;init_qpattr);</code> which fails to create the queue pair.</p>

<p><strong>Updated: Registered the memory before creating Queue Pair. But still it is showing invalid argument error (error code -22) for ib_create_qp</strong></p>

<pre><code>#include &lt;linux/kernel.h&gt;
#include &lt;linux/init.h&gt;
#include &lt;linux/module.h&gt;
#include &lt;linux/list.h&gt;
#include &lt;linux/module.h&gt;
#include &lt;linux/err.h&gt;
#include "myClient.h"


struct workqueue_struct *myClient_workqueue;
struct ib_sa_client myClient_sa_client;
/*
static void myClient_add_one(struct ib_device *device);
static void myClient_remove_one(struct ib_device *device);
*/

struct ib_pd *mypd;
struct ib_cq *myrcvcq;
struct ib_cq *myClientsendcq;
struct ib_qp *myClientqp;
struct ib_mr *mymr;

void myClient_ib_recvcompletion(struct ib_cq *cq)
{
    printk("A user-specified callback that is invoked when a completion event occurs on the CQ.\n");
}


void myClient_ib_sendcompletion(struct ib_cq *cq)
{
        printk("A user-specified callback that is invoked when a completion event occurs on the CQ.\n");
}
static void my_qp_event_handler(struct ib_event *myqpAsyncEvent, void *anyPointer)
{
        printk(KERN_INFO "Dummy affiliated asynchronous event occured function called \n");
}


static void myClient_add_one(struct ib_device *device)
{
    union ib_gid tmp_gid;
    int ret;
    int hcaport = 1;
    int result = -ENOMEM;
    u16 port1Pkey;
    struct ib_port_attr attr;

        ret = ib_query_port(device,hcaport,&amp;attr);
        printk("ib query port result %d  \n", ret);

//  Creating the Protection Domain for RDMA
    mypd = ib_alloc_pd(device);

    if(IS_ERR(mypd)){
        printk(KERN_INFO "Failed to allocate PD\n");
        return;
    }
    else{
        printk(KERN_INFO "1Successfully allocated the PD\n");
        pdset = true;
    }
// Registering Memory
    mymr = ib_get_dma_mr(mypd,IB_ACCESS_LOCAL_WRITE | IB_ACCESS_REMOTE_READ| IB_ACCESS_REMOTE_WRITE);
    if(IS_ERR(mymr)){
            printk("failed to register memory :( %d \n",PTR_ERR(mymr));
    }else{
            printk(KERN_INFO "Successfully registered memory region :) \n");
    }
// End Registering Memory
//  Creating the receive completion queue for RDMA
    myrcvcq = ib_create_cq(device,myClient_ib_recvcompletion,NULL,NULL,myClient_recvq_size,0);
        if(IS_ERR(myrcvcq)){
                pr_err("%s:%d error code for receive cq%d\n", __func__, __LINE__, PTR_ERR(myrcvcq));
                //printk("Error creating QP: %d \n",PTR_ERR(myClientqp));
        }
    else{
        printk("Recieve CQ successfully created in address: %x \n",myrcvcq);
    }

//  Creating the send completion queue for RDMA
    myClientsendcq = ib_create_cq(device,myClient_ib_sendcompletion, NULL, NULL,myClient_sendq_size,0 );
        if(IS_ERR(myClientsendcq)){
                pr_err("%s:%d scqerror code for send cq%d\n", __func__, __LINE__, PTR_ERR(myClientsendcq));
                //printk("Error creating QP: %d \n",PTR_ERR(myClientqp));
        }
        else{
                printk("1Send CQ successfully created in address: %x \n",myClientsendcq);
        }

//  Creating the queue pair
//      Creating the queue pair

        struct ib_qp_init_attr init_qpattr;

        memset(&amp;init_qpattr,0,sizeof(init_qpattr));
        init_qpattr.event_handler = myClient_qp_event_handler;
        init_qpattr.cap.max_send_wr = 2;
        init_qpattr.cap.max_recv_wr = 2;
        init_qpattr.cap.max_recv_sge = 1;
        init_qpattr.cap.max_send_sge = 1;
        init_qpattr.sq_sig_type = IB_SIGNAL_ALL_WR;
        init_qpattr.qp_type = IB_QPT_UD;
        init_qpattr.send_cq = myClientsendcq;
        init_qpattr.recv_cq = myrcvcq;

        myClientqp = ib_create_qp(mypd,&amp;init_qpattr);

        if(IS_ERR(myClientqp)){
                pr_err("%s:%d error code %d\n", __func__, __LINE__, PTR_ERR(myClientqp));
                //printk("Error creating QP: %d \n",PTR_ERR(myClientqp));
        }
        else{
                printk(KERN_INFO "1The queue pair is successfully created \n");
                qpcreated = true;
        }



}
static void myClient_remove_one(struct ib_device *device)
{
}

static struct ib_client my_client = {
        .name   = "myRDMAclient",
        .add    = myClient_add_one,
        .remove = myClient_remove_one
};


static int __init myRDMAclient_init(void)
{
    int ret;

    ret = ib_register_client(&amp;my_client);
    if(ret){
        //printk(KERN_ALERT "KERN_ERR Failed to register IB client\n");
        goto err_sa;
    }
    printk(KERN_ALERT "lKERN_INFO Successfully registered myRDMAclient module \n");
    return 0;

err_sa:


    return ret;
}


module_init(myRDMAclient_init);
</code></pre>