device.c

Go to the documentation of this file.

/*
 * Copyright (c) 2009-2010 Chelsio, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials
 *    provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/debugfs.h>
#include <linux/vmalloc.h>

#include <rdma/ib_verbs.h>

#include "iw_cxgb4.h"

#define DRV_VERSION "0.1"

MODULE_AUTHOR("Steve Wise");
MODULE_DESCRIPTION("Chelsio T4 RDMA Driver");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_VERSION(DRV_VERSION);

struct uld_ctx {
    struct list_head entry;
    struct cxgb4_lld_info lldi;
    struct c4iw_dev *dev;
};

static LIST_HEAD(uld_ctx_list);
static DEFINE_MUTEX(dev_mutex);

static struct dentry *c4iw_debugfs_root;

struct c4iw_debugfs_data {
    struct c4iw_dev *devp;
    char *buf;
    int bufsize;
    int pos;
};

static int count_idrs(int id, void *p, void *data)
{
    int *countp = data;

    *countp = *countp + 1;
    return 0;
}

static ssize_t debugfs_read(struct file *file, char __user *buf, size_t count,
                loff_t *ppos)
{
    struct c4iw_debugfs_data *d = file->private_data;

    return simple_read_from_buffer(buf, count, ppos, d->buf, d->pos);
}

static int dump_qp(int id, void *p, void *data)
{
    struct c4iw_qp *qp = p;
    struct c4iw_debugfs_data *qpd = data;
    int space;
    int cc;

    if (id != qp->wq.sq.qid)
        return 0;

    space = qpd->bufsize - qpd->pos - 1;
    if (space == 0)
        return 1;

    if (qp->ep)
        cc = snprintf(qpd->buf + qpd->pos, space,
                 "qp sq id %u rq id %u state %u onchip %u "
                 "ep tid %u state %u %pI4:%u->%pI4:%u\n",
                 qp->wq.sq.qid, qp->wq.rq.qid, (int)qp->attr.state,
                 qp->wq.sq.flags & T4_SQ_ONCHIP,
                 qp->ep->hwtid, (int)qp->ep->com.state,
                 &qp->ep->com.local_addr.sin_addr.s_addr,
                 ntohs(qp->ep->com.local_addr.sin_port),
                 &qp->ep->com.remote_addr.sin_addr.s_addr,
                 ntohs(qp->ep->com.remote_addr.sin_port));
    else
        cc = snprintf(qpd->buf + qpd->pos, space,
                 "qp sq id %u rq id %u state %u onchip %u\n",
                  qp->wq.sq.qid, qp->wq.rq.qid,
                  (int)qp->attr.state,
                  qp->wq.sq.flags & T4_SQ_ONCHIP);
    if (cc < space)
        qpd->pos += cc;
    return 0;
}

static int qp_release(struct inode *inode, struct file *file)
{
    struct c4iw_debugfs_data *qpd = file->private_data;
    if (!qpd) {
        printk(KERN_INFO "%s null qpd?\n", __func__);
        return 0;
    }
    vfree(qpd->buf);
    kfree(qpd);
    return 0;
}

static int qp_open(struct inode *inode, struct file *file)
{
    struct c4iw_debugfs_data *qpd;
    int ret = 0;
    int count = 1;

    qpd = kmalloc(sizeof *qpd, GFP_KERNEL);
    if (!qpd) {
        ret = -ENOMEM;
        goto out;
    }
    qpd->devp = inode->i_private;
    qpd->pos = 0;

    spin_lock_irq(&qpd->devp->lock);
    idr_for_each(&qpd->devp->qpidr, count_idrs, &count);
    spin_unlock_irq(&qpd->devp->lock);

    qpd->bufsize = count * 128;
    qpd->buf = vmalloc(qpd->bufsize);
    if (!qpd->buf) {
        ret = -ENOMEM;
        goto err1;
    }

    spin_lock_irq(&qpd->devp->lock);
    idr_for_each(&qpd->devp->qpidr, dump_qp, qpd);
    spin_unlock_irq(&qpd->devp->lock);

    qpd->buf[qpd->pos++] = 0;
    file->private_data = qpd;
    goto out;
err1:
    kfree(qpd);
out:
    return ret;
}

static const struct file_operations qp_debugfs_fops = {
    .owner   = THIS_MODULE,
    .open    = qp_open,
    .release = qp_release,
    .read    = debugfs_read,
    .llseek  = default_llseek,
};

static int dump_stag(int id, void *p, void *data)
{
    struct c4iw_debugfs_data *stagd = data;
    int space;
    int cc;

    space = stagd->bufsize - stagd->pos - 1;
    if (space == 0)
        return 1;

    cc = snprintf(stagd->buf + stagd->pos, space, "0x%x\n", id<<8);
    if (cc < space)
        stagd->pos += cc;
    return 0;
}

static int stag_release(struct inode *inode, struct file *file)
{
    struct c4iw_debugfs_data *stagd = file->private_data;
    if (!stagd) {
        printk(KERN_INFO "%s null stagd?\n", __func__);
        return 0;
    }
    kfree(stagd->buf);
    kfree(stagd);
    return 0;
}

static int stag_open(struct inode *inode, struct file *file)
{
    struct c4iw_debugfs_data *stagd;
    int ret = 0;
    int count = 1;

    stagd = kmalloc(sizeof *stagd, GFP_KERNEL);
    if (!stagd) {
        ret = -ENOMEM;
        goto out;
    }
    stagd->devp = inode->i_private;
    stagd->pos = 0;

    spin_lock_irq(&stagd->devp->lock);
    idr_for_each(&stagd->devp->mmidr, count_idrs, &count);
    spin_unlock_irq(&stagd->devp->lock);

    stagd->bufsize = count * sizeof("0x12345678\n");
    stagd->buf = kmalloc(stagd->bufsize, GFP_KERNEL);
    if (!stagd->buf) {
        ret = -ENOMEM;
        goto err1;
    }

    spin_lock_irq(&stagd->devp->lock);
    idr_for_each(&stagd->devp->mmidr, dump_stag, stagd);
    spin_unlock_irq(&stagd->devp->lock);

    stagd->buf[stagd->pos++] = 0;
    file->private_data = stagd;
    goto out;
err1:
    kfree(stagd);
out:
    return ret;
}

static const struct file_operations stag_debugfs_fops = {
    .owner   = THIS_MODULE,
    .open    = stag_open,
    .release = stag_release,
    .read    = debugfs_read,
    .llseek  = default_llseek,
};

static char *db_state_str[] = {"NORMAL", "FLOW_CONTROL", "RECOVERY"};

static int stats_show(struct seq_file *seq, void *v)
{
    struct c4iw_dev *dev = seq->private;

    seq_printf(seq, "   Object: %10s %10s %10s %10s\n", "Total", "Current",
           "Max", "Fail");
    seq_printf(seq, "     PDID: %10llu %10llu %10llu %10llu\n",
            dev->rdev.stats.pd.total, dev->rdev.stats.pd.cur,
            dev->rdev.stats.pd.max, dev->rdev.stats.pd.fail);
    seq_printf(seq, "      QID: %10llu %10llu %10llu %10llu\n",
            dev->rdev.stats.qid.total, dev->rdev.stats.qid.cur,
            dev->rdev.stats.qid.max, dev->rdev.stats.qid.fail);
    seq_printf(seq, "   TPTMEM: %10llu %10llu %10llu %10llu\n",
            dev->rdev.stats.stag.total, dev->rdev.stats.stag.cur,
            dev->rdev.stats.stag.max, dev->rdev.stats.stag.fail);
    seq_printf(seq, "   PBLMEM: %10llu %10llu %10llu %10llu\n",
            dev->rdev.stats.pbl.total, dev->rdev.stats.pbl.cur,
            dev->rdev.stats.pbl.max, dev->rdev.stats.pbl.fail);
    seq_printf(seq, "   RQTMEM: %10llu %10llu %10llu %10llu\n",
            dev->rdev.stats.rqt.total, dev->rdev.stats.rqt.cur,
            dev->rdev.stats.rqt.max, dev->rdev.stats.rqt.fail);
    seq_printf(seq, "  OCQPMEM: %10llu %10llu %10llu %10llu\n",
            dev->rdev.stats.ocqp.total, dev->rdev.stats.ocqp.cur,
            dev->rdev.stats.ocqp.max, dev->rdev.stats.ocqp.fail);
    seq_printf(seq, "  DB FULL: %10llu\n", dev->rdev.stats.db_full);
    seq_printf(seq, " DB EMPTY: %10llu\n", dev->rdev.stats.db_empty);
    seq_printf(seq, "  DB DROP: %10llu\n", dev->rdev.stats.db_drop);
    seq_printf(seq, " DB State: %s Transitions %llu\n",
           db_state_str[dev->db_state],
           dev->rdev.stats.db_state_transitions);
    return 0;
}

static int stats_open(struct inode *inode, struct file *file)
{
    return single_open(file, stats_show, inode->i_private);
}

static ssize_t stats_clear(struct file *file, const char __user *buf,
        size_t count, loff_t *pos)
{
    struct c4iw_dev *dev = ((struct seq_file *)file->private_data)->private;

    mutex_lock(&dev->rdev.stats.lock);
    dev->rdev.stats.pd.max = 0;
    dev->rdev.stats.pd.fail = 0;
    dev->rdev.stats.qid.max = 0;
    dev->rdev.stats.qid.fail = 0;
    dev->rdev.stats.stag.max = 0;
    dev->rdev.stats.stag.fail = 0;
    dev->rdev.stats.pbl.max = 0;
    dev->rdev.stats.pbl.fail = 0;
    dev->rdev.stats.rqt.max = 0;
    dev->rdev.stats.rqt.fail = 0;
    dev->rdev.stats.ocqp.max = 0;
    dev->rdev.stats.ocqp.fail = 0;
    dev->rdev.stats.db_full = 0;
    dev->rdev.stats.db_empty = 0;
    dev->rdev.stats.db_drop = 0;
    dev->rdev.stats.db_state_transitions = 0;
    mutex_unlock(&dev->rdev.stats.lock);
    return count;
}

static const struct file_operations stats_debugfs_fops = {
    .owner   = THIS_MODULE,
    .open    = stats_open,
    .release = single_release,
    .read    = seq_read,
    .llseek  = seq_lseek,
    .write   = stats_clear,
};

static int setup_debugfs(struct c4iw_dev *devp)
{
    struct dentry *de;

    if (!devp->debugfs_root)
        return -1;

    de = debugfs_create_file("qps", S_IWUSR, devp->debugfs_root,
                 (void *)devp, &qp_debugfs_fops);
    if (de && de->d_inode)
        de->d_inode->i_size = 4096;

    de = debugfs_create_file("stags", S_IWUSR, devp->debugfs_root,
                 (void *)devp, &stag_debugfs_fops);
    if (de && de->d_inode)
        de->d_inode->i_size = 4096;

    de = debugfs_create_file("stats", S_IWUSR, devp->debugfs_root,
            (void *)devp, &stats_debugfs_fops);
    if (de && de->d_inode)
        de->d_inode->i_size = 4096;

    return 0;
}

void c4iw_release_dev_ucontext(struct c4iw_rdev *rdev,
                   struct c4iw_dev_ucontext *uctx)
{
    struct list_head *pos, *nxt;
    struct c4iw_qid_list *entry;

    mutex_lock(&uctx->lock);
    list_for_each_safe(pos, nxt, &uctx->qpids) {
        entry = list_entry(pos, struct c4iw_qid_list, entry);
        list_del_init(&entry->entry);
        if (!(entry->qid & rdev->qpmask)) {
            c4iw_put_resource(&rdev->resource.qid_table,
                      entry->qid);
            mutex_lock(&rdev->stats.lock);
            rdev->stats.qid.cur -= rdev->qpmask + 1;
            mutex_unlock(&rdev->stats.lock);
        }
        kfree(entry);
    }

    list_for_each_safe(pos, nxt, &uctx->qpids) {
        entry = list_entry(pos, struct c4iw_qid_list, entry);
        list_del_init(&entry->entry);
        kfree(entry);
    }
    mutex_unlock(&uctx->lock);
}

void c4iw_init_dev_ucontext(struct c4iw_rdev *rdev,
                struct c4iw_dev_ucontext *uctx)
{
    INIT_LIST_HEAD(&uctx->qpids);
    INIT_LIST_HEAD(&uctx->cqids);
    mutex_init(&uctx->lock);
}

/* Caller takes care of locking if needed */
static int c4iw_rdev_open(struct c4iw_rdev *rdev)
{
    int err;

    c4iw_init_dev_ucontext(rdev, &rdev->uctx);

    /*
     * qpshift is the number of bits to shift the qpid left in order
     * to get the correct address of the doorbell for that qp.
     */
    rdev->qpshift = PAGE_SHIFT - ilog2(rdev->lldi.udb_density);
    rdev->qpmask = rdev->lldi.udb_density - 1;
    rdev->cqshift = PAGE_SHIFT - ilog2(rdev->lldi.ucq_density);
    rdev->cqmask = rdev->lldi.ucq_density - 1;
    PDBG("%s dev %s stag start 0x%0x size 0x%0x num stags %d "
         "pbl start 0x%0x size 0x%0x rq start 0x%0x size 0x%0x "
         "qp qid start %u size %u cq qid start %u size %u\n",
         __func__, pci_name(rdev->lldi.pdev), rdev->lldi.vr->stag.start,
         rdev->lldi.vr->stag.size, c4iw_num_stags(rdev),
         rdev->lldi.vr->pbl.start,
         rdev->lldi.vr->pbl.size, rdev->lldi.vr->rq.start,
         rdev->lldi.vr->rq.size,
         rdev->lldi.vr->qp.start,
         rdev->lldi.vr->qp.size,
         rdev->lldi.vr->cq.start,
         rdev->lldi.vr->cq.size);
    PDBG("udb len 0x%x udb base %p db_reg %p gts_reg %p qpshift %lu "
         "qpmask 0x%x cqshift %lu cqmask 0x%x\n",
         (unsigned)pci_resource_len(rdev->lldi.pdev, 2),
         (void *)pci_resource_start(rdev->lldi.pdev, 2),
         rdev->lldi.db_reg,
         rdev->lldi.gts_reg,
         rdev->qpshift, rdev->qpmask,
         rdev->cqshift, rdev->cqmask);

    if (c4iw_num_stags(rdev) == 0) {
        err = -EINVAL;
        goto err1;
    }

    rdev->stats.pd.total = T4_MAX_NUM_PD;
    rdev->stats.stag.total = rdev->lldi.vr->stag.size;
    rdev->stats.pbl.total = rdev->lldi.vr->pbl.size;
    rdev->stats.rqt.total = rdev->lldi.vr->rq.size;
    rdev->stats.ocqp.total = rdev->lldi.vr->ocq.size;
    rdev->stats.qid.total = rdev->lldi.vr->qp.size;

    err = c4iw_init_resource(rdev, c4iw_num_stags(rdev), T4_MAX_NUM_PD);
    if (err) {
        printk(KERN_ERR MOD "error %d initializing resources\n", err);
        goto err1;
    }
    err = c4iw_pblpool_create(rdev);
    if (err) {
        printk(KERN_ERR MOD "error %d initializing pbl pool\n", err);
        goto err2;
    }
    err = c4iw_rqtpool_create(rdev);
    if (err) {
        printk(KERN_ERR MOD "error %d initializing rqt pool\n", err);
        goto err3;
    }
    err = c4iw_ocqp_pool_create(rdev);
    if (err) {
        printk(KERN_ERR MOD "error %d initializing ocqp pool\n", err);
        goto err4;
    }
    return 0;
err4:
    c4iw_rqtpool_destroy(rdev);
err3:
    c4iw_pblpool_destroy(rdev);
err2:
    c4iw_destroy_resource(&rdev->resource);
err1:
    return err;
}

static void c4iw_rdev_close(struct c4iw_rdev *rdev)
{
    c4iw_pblpool_destroy(rdev);
    c4iw_rqtpool_destroy(rdev);
    c4iw_destroy_resource(&rdev->resource);
}

static void c4iw_dealloc(struct uld_ctx *ctx)
{
    c4iw_rdev_close(&ctx->dev->rdev);
    idr_destroy(&ctx->dev->cqidr);
    idr_destroy(&ctx->dev->qpidr);
    idr_destroy(&ctx->dev->mmidr);
    iounmap(ctx->dev->rdev.oc_mw_kva);
    ib_dealloc_device(&ctx->dev->ibdev);
    ctx->dev = NULL;
}

static void c4iw_remove(struct uld_ctx *ctx)
{
    PDBG("%s c4iw_dev %p\n", __func__,  ctx->dev);
    c4iw_unregister_device(ctx->dev);
    c4iw_dealloc(ctx);
}

static int rdma_supported(const struct cxgb4_lld_info *infop)
{
    return infop->vr->stag.size > 0 && infop->vr->pbl.size > 0 &&
           infop->vr->rq.size > 0 && infop->vr->qp.size > 0 &&
           infop->vr->cq.size > 0 && infop->vr->ocq.size > 0;
}

static struct c4iw_dev *c4iw_alloc(const struct cxgb4_lld_info *infop)
{
    struct c4iw_dev *devp;
    int ret;

    if (!rdma_supported(infop)) {
        printk(KERN_INFO MOD "%s: RDMA not supported on this device.\n",
               pci_name(infop->pdev));
        return ERR_PTR(-ENOSYS);
    }
    devp = (struct c4iw_dev *)ib_alloc_device(sizeof(*devp));
    if (!devp) {
        printk(KERN_ERR MOD "Cannot allocate ib device\n");
        return ERR_PTR(-ENOMEM);
    }
    devp->rdev.lldi = *infop;

    devp->rdev.oc_mw_pa = pci_resource_start(devp->rdev.lldi.pdev, 2) +
        (pci_resource_len(devp->rdev.lldi.pdev, 2) -
         roundup_pow_of_two(devp->rdev.lldi.vr->ocq.size));
    devp->rdev.oc_mw_kva = ioremap_wc(devp->rdev.oc_mw_pa,
                           devp->rdev.lldi.vr->ocq.size);

    PDBG(KERN_INFO MOD "ocq memory: "
           "hw_start 0x%x size %u mw_pa 0x%lx mw_kva %p\n",
           devp->rdev.lldi.vr->ocq.start, devp->rdev.lldi.vr->ocq.size,
           devp->rdev.oc_mw_pa, devp->rdev.oc_mw_kva);

    ret = c4iw_rdev_open(&devp->rdev);
    if (ret) {
        printk(KERN_ERR MOD "Unable to open CXIO rdev err %d\n", ret);
        ib_dealloc_device(&devp->ibdev);
        return ERR_PTR(ret);
    }

    idr_init(&devp->cqidr);
    idr_init(&devp->qpidr);
    idr_init(&devp->mmidr);
    spin_lock_init(&devp->lock);
    mutex_init(&devp->rdev.stats.lock);
    mutex_init(&devp->db_mutex);

    if (c4iw_debugfs_root) {
        devp->debugfs_root = debugfs_create_dir(
                    pci_name(devp->rdev.lldi.pdev),
                    c4iw_debugfs_root);
        setup_debugfs(devp);
    }
    return devp;
}

static void *c4iw_uld_add(const struct cxgb4_lld_info *infop)
{
    struct uld_ctx *ctx;
    static int vers_printed;
    int i;

    if (!vers_printed++)
        printk(KERN_INFO MOD "Chelsio T4 RDMA Driver - version %s\n",
               DRV_VERSION);

    ctx = kzalloc(sizeof *ctx, GFP_KERNEL);
    if (!ctx) {
        ctx = ERR_PTR(-ENOMEM);
        goto out;
    }
    ctx->lldi = *infop;

    PDBG("%s found device %s nchan %u nrxq %u ntxq %u nports %u\n",
         __func__, pci_name(ctx->lldi.pdev),
         ctx->lldi.nchan, ctx->lldi.nrxq,
         ctx->lldi.ntxq, ctx->lldi.nports);

    mutex_lock(&dev_mutex);
    list_add_tail(&ctx->entry, &uld_ctx_list);
    mutex_unlock(&dev_mutex);

    for (i = 0; i < ctx->lldi.nrxq; i++)
        PDBG("rxqid[%u] %u\n", i, ctx->lldi.rxq_ids[i]);
out:
    return ctx;
}

static int c4iw_uld_rx_handler(void *handle, const __be64 *rsp,
            const struct pkt_gl *gl)
{
    struct uld_ctx *ctx = handle;
    struct c4iw_dev *dev = ctx->dev;
    struct sk_buff *skb;
    const struct cpl_act_establish *rpl;
    unsigned int opcode;

    if (gl == NULL) {
        /* omit RSS and rsp_ctrl at end of descriptor */
        unsigned int len = 64 - sizeof(struct rsp_ctrl) - 8;

        skb = alloc_skb(256, GFP_ATOMIC);
        if (!skb)
            goto nomem;
        __skb_put(skb, len);
        skb_copy_to_linear_data(skb, &rsp[1], len);
    } else if (gl == CXGB4_MSG_AN) {
        const struct rsp_ctrl *rc = (void *)rsp;

        u32 qid = be32_to_cpu(rc->pldbuflen_qid);
        c4iw_ev_handler(dev, qid);
        return 0;
    } else {
        skb = cxgb4_pktgl_to_skb(gl, 128, 128);
        if (unlikely(!skb))
            goto nomem;
    }

    rpl = cplhdr(skb);
    opcode = rpl->ot.opcode;

    if (c4iw_handlers[opcode])
        c4iw_handlers[opcode](dev, skb);
    else
        printk(KERN_INFO "%s no handler opcode 0x%x...\n", __func__,
               opcode);

    return 0;
nomem:
    return -1;
}

static int c4iw_uld_state_change(void *handle, enum cxgb4_state new_state)
{
    struct uld_ctx *ctx = handle;

    PDBG("%s new_state %u\n", __func__, new_state);
    switch (new_state) {
    case CXGB4_STATE_UP:
        printk(KERN_INFO MOD "%s: Up\n", pci_name(ctx->lldi.pdev));
        if (!ctx->dev) {
            int ret;

            ctx->dev = c4iw_alloc(&ctx->lldi);
            if (IS_ERR(ctx->dev)) {
                printk(KERN_ERR MOD
                       "%s: initialization failed: %ld\n",
                       pci_name(ctx->lldi.pdev),
                       PTR_ERR(ctx->dev));
                ctx->dev = NULL;
                break;
            }
            ret = c4iw_register_device(ctx->dev);
            if (ret) {
                printk(KERN_ERR MOD
                       "%s: RDMA registration failed: %d\n",
                       pci_name(ctx->lldi.pdev), ret);
                c4iw_dealloc(ctx);
            }
        }
        break;
    case CXGB4_STATE_DOWN:
        printk(KERN_INFO MOD "%s: Down\n",
               pci_name(ctx->lldi.pdev));
        if (ctx->dev)
            c4iw_remove(ctx);
        break;
    case CXGB4_STATE_START_RECOVERY:
        printk(KERN_INFO MOD "%s: Fatal Error\n",
               pci_name(ctx->lldi.pdev));
        if (ctx->dev) {
            struct ib_event event;

            ctx->dev->rdev.flags |= T4_FATAL_ERROR;
            memset(&event, 0, sizeof event);
            event.event  = IB_EVENT_DEVICE_FATAL;
            event.device = &ctx->dev->ibdev;
            ib_dispatch_event(&event);
            c4iw_remove(ctx);
        }
        break;
    case CXGB4_STATE_DETACH:
        printk(KERN_INFO MOD "%s: Detach\n",
               pci_name(ctx->lldi.pdev));
        if (ctx->dev)
            c4iw_remove(ctx);
        break;
    }
    return 0;
}

static int disable_qp_db(int id, void *p, void *data)
{
    struct c4iw_qp *qp = p;

    t4_disable_wq_db(&qp->wq);
    return 0;
}

static void stop_queues(struct uld_ctx *ctx)
{
    spin_lock_irq(&ctx->dev->lock);
    if (ctx->dev->db_state == NORMAL) {
        ctx->dev->rdev.stats.db_state_transitions++;
        ctx->dev->db_state = FLOW_CONTROL;
        idr_for_each(&ctx->dev->qpidr, disable_qp_db, NULL);
    }
    spin_unlock_irq(&ctx->dev->lock);
}

static int enable_qp_db(int id, void *p, void *data)
{
    struct c4iw_qp *qp = p;

    t4_enable_wq_db(&qp->wq);
    return 0;
}

static void resume_queues(struct uld_ctx *ctx)
{
    spin_lock_irq(&ctx->dev->lock);
    if (ctx->dev->qpcnt <= db_fc_threshold &&
        ctx->dev->db_state == FLOW_CONTROL) {
        ctx->dev->db_state = NORMAL;
        ctx->dev->rdev.stats.db_state_transitions++;
        idr_for_each(&ctx->dev->qpidr, enable_qp_db, NULL);
    }
    spin_unlock_irq(&ctx->dev->lock);
}

struct qp_list {
    unsigned idx;
    struct c4iw_qp **qps;
};

static int add_and_ref_qp(int id, void *p, void *data)
{
    struct qp_list *qp_listp = data;
    struct c4iw_qp *qp = p;

    c4iw_qp_add_ref(&qp->ibqp);
    qp_listp->qps[qp_listp->idx++] = qp;
    return 0;
}

static int count_qps(int id, void *p, void *data)
{
    unsigned *countp = data;
    (*countp)++;
    return 0;
}

static void deref_qps(struct qp_list qp_list)
{
    int idx;

    for (idx = 0; idx < qp_list.idx; idx++)
        c4iw_qp_rem_ref(&qp_list.qps[idx]->ibqp);
}

static void recover_lost_dbs(struct uld_ctx *ctx, struct qp_list *qp_list)
{
    int idx;
    int ret;

    for (idx = 0; idx < qp_list->idx; idx++) {
        struct c4iw_qp *qp = qp_list->qps[idx];

        ret = cxgb4_sync_txq_pidx(qp->rhp->rdev.lldi.ports[0],
                      qp->wq.sq.qid,
                      t4_sq_host_wq_pidx(&qp->wq),
                      t4_sq_wq_size(&qp->wq));
        if (ret) {
            printk(KERN_ERR MOD "%s: Fatal error - "
                   "DB overflow recovery failed - "
                   "error syncing SQ qid %u\n",
                   pci_name(ctx->lldi.pdev), qp->wq.sq.qid);
            return;
        }

        ret = cxgb4_sync_txq_pidx(qp->rhp->rdev.lldi.ports[0],
                      qp->wq.rq.qid,
                      t4_rq_host_wq_pidx(&qp->wq),
                      t4_rq_wq_size(&qp->wq));

        if (ret) {
            printk(KERN_ERR MOD "%s: Fatal error - "
                   "DB overflow recovery failed - "
                   "error syncing RQ qid %u\n",
                   pci_name(ctx->lldi.pdev), qp->wq.rq.qid);
            return;
        }

        /* Wait for the dbfifo to drain */
        while (cxgb4_dbfifo_count(qp->rhp->rdev.lldi.ports[0], 1) > 0) {
            set_current_state(TASK_UNINTERRUPTIBLE);
            schedule_timeout(usecs_to_jiffies(10));
        }
    }
}

static void recover_queues(struct uld_ctx *ctx)
{
    int count = 0;
    struct qp_list qp_list;
    int ret;

    /* lock out kernel db ringers */
    mutex_lock(&ctx->dev->db_mutex);

    /* put all queues in to recovery mode */
    spin_lock_irq(&ctx->dev->lock);
    ctx->dev->db_state = RECOVERY;
    ctx->dev->rdev.stats.db_state_transitions++;
    idr_for_each(&ctx->dev->qpidr, disable_qp_db, NULL);
    spin_unlock_irq(&ctx->dev->lock);

    /* slow everybody down */
    set_current_state(TASK_UNINTERRUPTIBLE);
    schedule_timeout(usecs_to_jiffies(1000));

    /* Wait for the dbfifo to completely drain. */
    while (cxgb4_dbfifo_count(ctx->dev->rdev.lldi.ports[0], 1) > 0) {
        set_current_state(TASK_UNINTERRUPTIBLE);
        schedule_timeout(usecs_to_jiffies(10));
    }

    /* flush the SGE contexts */
    ret = cxgb4_flush_eq_cache(ctx->dev->rdev.lldi.ports[0]);
    if (ret) {
        printk(KERN_ERR MOD "%s: Fatal error - DB overflow recovery failed\n",
               pci_name(ctx->lldi.pdev));
        goto out;
    }

    /* Count active queues so we can build a list of queues to recover */
    spin_lock_irq(&ctx->dev->lock);
    idr_for_each(&ctx->dev->qpidr, count_qps, &count);

    qp_list.qps = kzalloc(count * sizeof *qp_list.qps, GFP_ATOMIC);
    if (!qp_list.qps) {
        printk(KERN_ERR MOD "%s: Fatal error - DB overflow recovery failed\n",
               pci_name(ctx->lldi.pdev));
        spin_unlock_irq(&ctx->dev->lock);
        goto out;
    }
    qp_list.idx = 0;

    /* add and ref each qp so it doesn't get freed */
    idr_for_each(&ctx->dev->qpidr, add_and_ref_qp, &qp_list);

    spin_unlock_irq(&ctx->dev->lock);

    /* now traverse the list in a safe context to recover the db state*/
    recover_lost_dbs(ctx, &qp_list);

    /* we're almost done!  deref the qps and clean up */
    deref_qps(qp_list);
    kfree(qp_list.qps);

    /* Wait for the dbfifo to completely drain again */
    while (cxgb4_dbfifo_count(ctx->dev->rdev.lldi.ports[0], 1) > 0) {
        set_current_state(TASK_UNINTERRUPTIBLE);
        schedule_timeout(usecs_to_jiffies(10));
    }

    /* resume the queues */
    spin_lock_irq(&ctx->dev->lock);
    if (ctx->dev->qpcnt > db_fc_threshold)
        ctx->dev->db_state = FLOW_CONTROL;
    else {
        ctx->dev->db_state = NORMAL;
        idr_for_each(&ctx->dev->qpidr, enable_qp_db, NULL);
    }
    ctx->dev->rdev.stats.db_state_transitions++;
    spin_unlock_irq(&ctx->dev->lock);

out:
    /* start up kernel db ringers again */
    mutex_unlock(&ctx->dev->db_mutex);
}

static int c4iw_uld_control(void *handle, enum cxgb4_control control, ...)
{
    struct uld_ctx *ctx = handle;

    switch (control) {
    case CXGB4_CONTROL_DB_FULL:
        stop_queues(ctx);
        mutex_lock(&ctx->dev->rdev.stats.lock);
        ctx->dev->rdev.stats.db_full++;
        mutex_unlock(&ctx->dev->rdev.stats.lock);
        break;
    case CXGB4_CONTROL_DB_EMPTY:
        resume_queues(ctx);
        mutex_lock(&ctx->dev->rdev.stats.lock);
        ctx->dev->rdev.stats.db_empty++;
        mutex_unlock(&ctx->dev->rdev.stats.lock);
        break;
    case CXGB4_CONTROL_DB_DROP:
        recover_queues(ctx);
        mutex_lock(&ctx->dev->rdev.stats.lock);
        ctx->dev->rdev.stats.db_drop++;
        mutex_unlock(&ctx->dev->rdev.stats.lock);
        break;
    default:
        printk(KERN_WARNING MOD "%s: unknown control cmd %u\n",
               pci_name(ctx->lldi.pdev), control);
        break;
    }
    return 0;
}

static struct cxgb4_uld_info c4iw_uld_info = {
    .name = DRV_NAME,
    .add = c4iw_uld_add,
    .rx_handler = c4iw_uld_rx_handler,
    .state_change = c4iw_uld_state_change,
    .control = c4iw_uld_control,
};

static int __init c4iw_init_module(void)
{
    int err;

    err = c4iw_cm_init();
    if (err)
        return err;

    c4iw_debugfs_root = debugfs_create_dir(DRV_NAME, NULL);
    if (!c4iw_debugfs_root)
        printk(KERN_WARNING MOD
               "could not create debugfs entry, continuing\n");

    cxgb4_register_uld(CXGB4_ULD_RDMA, &c4iw_uld_info);

    return 0;
}

static void __exit c4iw_exit_module(void)
{
    struct uld_ctx *ctx, *tmp;

    mutex_lock(&dev_mutex);
    list_for_each_entry_safe(ctx, tmp, &uld_ctx_list, entry) {
        if (ctx->dev)
            c4iw_remove(ctx);
        kfree(ctx);
    }
    mutex_unlock(&dev_mutex);
    cxgb4_unregister_uld(CXGB4_ULD_RDMA);
    c4iw_cm_term();
    debugfs_remove_recursive(c4iw_debugfs_root);
}

module_init(c4iw_init_module);
module_exit(c4iw_exit_module);