spi-topcliff-pch: add recovery processing in case wait-event timeout

[zen-stable.git] / drivers / infiniband / hw / qib / qib_user_sdma.c

/*
 * Copyright (c) 2007, 2008, 2009 QLogic Corporation. 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/mm.h>
#include <linux/types.h>
#include <linux/device.h>
#include <linux/dmapool.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/highmem.h>
#include <linux/io.h>
#include <linux/uio.h>
#include <linux/rbtree.h>
#include <linux/spinlock.h>
#include <linux/delay.h>

#include "qib.h"
#include "qib_user_sdma.h"

/* minimum size of header */
#define QIB_USER_SDMA_MIN_HEADER_LENGTH 64
/* expected size of headers (for dma_pool) */
#define QIB_USER_SDMA_EXP_HEADER_LENGTH 64
/* attempt to drain the queue for 5secs */
#define QIB_USER_SDMA_DRAIN_TIMEOUT 500

struct qib_user_sdma_pkt {
        u8 naddr;               /* dimension of addr (1..3) ... */
        u32 counter;            /* sdma pkts queued counter for this entry */
        u64 added;              /* global descq number of entries */

        struct {
                u32 offset;                     /* offset for kvaddr, addr */
                u32 length;                     /* length in page */
                u8  put_page;                   /* should we put_page? */
                u8  dma_mapped;                 /* is page dma_mapped? */
                struct page *page;              /* may be NULL (coherent mem) */
                void *kvaddr;                   /* FIXME: only for pio hack */
                dma_addr_t addr;
        } addr[4];   /* max pages, any more and we coalesce */
        struct list_head list;  /* list element */
};

struct qib_user_sdma_queue {
        /*
         * pkts sent to dma engine are queued on this
         * list head.  the type of the elements of this
         * list are struct qib_user_sdma_pkt...
         */
        struct list_head sent;

        /* headers with expected length are allocated from here... */
        char header_cache_name[64];
        struct dma_pool *header_cache;

        /* packets are allocated from the slab cache... */
        char pkt_slab_name[64];
        struct kmem_cache *pkt_slab;

        /* as packets go on the queued queue, they are counted... */
        u32 counter;
        u32 sent_counter;

        /* dma page table */
        struct rb_root dma_pages_root;

        /* protect everything above... */
        struct mutex lock;
};

struct qib_user_sdma_queue *
qib_user_sdma_queue_create(struct device *dev, int unit, int ctxt, int sctxt)
{
        struct qib_user_sdma_queue *pq =
                kmalloc(sizeof(struct qib_user_sdma_queue), GFP_KERNEL);

        if (!pq)
                goto done;

        pq->counter = 0;
        pq->sent_counter = 0;
        INIT_LIST_HEAD(&pq->sent);

        mutex_init(&pq->lock);

        snprintf(pq->pkt_slab_name, sizeof(pq->pkt_slab_name),
                 "qib-user-sdma-pkts-%u-%02u.%02u", unit, ctxt, sctxt);
        pq->pkt_slab = kmem_cache_create(pq->pkt_slab_name,
                                         sizeof(struct qib_user_sdma_pkt),
                                         0, 0, NULL);

        if (!pq->pkt_slab)
                goto err_kfree;

        snprintf(pq->header_cache_name, sizeof(pq->header_cache_name),
                 "qib-user-sdma-headers-%u-%02u.%02u", unit, ctxt, sctxt);
        pq->header_cache = dma_pool_create(pq->header_cache_name,
                                           dev,
                                           QIB_USER_SDMA_EXP_HEADER_LENGTH,
                                           4, 0);
        if (!pq->header_cache)
                goto err_slab;

        pq->dma_pages_root = RB_ROOT;

        goto done;

err_slab:
        kmem_cache_destroy(pq->pkt_slab);
err_kfree:
        kfree(pq);
        pq = NULL;

done:
        return pq;
}

static void qib_user_sdma_init_frag(struct qib_user_sdma_pkt *pkt,
                                    int i, size_t offset, size_t len,
                                    int put_page, int dma_mapped,
                                    struct page *page,
                                    void *kvaddr, dma_addr_t dma_addr)
{
        pkt->addr[i].offset = offset;
        pkt->addr[i].length = len;
        pkt->addr[i].put_page = put_page;
        pkt->addr[i].dma_mapped = dma_mapped;
        pkt->addr[i].page = page;
        pkt->addr[i].kvaddr = kvaddr;
        pkt->addr[i].addr = dma_addr;
}

static void qib_user_sdma_init_header(struct qib_user_sdma_pkt *pkt,
                                      u32 counter, size_t offset,
                                      size_t len, int dma_mapped,
                                      struct page *page,
                                      void *kvaddr, dma_addr_t dma_addr)
{
        pkt->naddr = 1;
        pkt->counter = counter;
        qib_user_sdma_init_frag(pkt, 0, offset, len, 0, dma_mapped, page,
                                kvaddr, dma_addr);
}

/* we've too many pages in the iovec, coalesce to a single page */
static int qib_user_sdma_coalesce(const struct qib_devdata *dd,
                                  struct qib_user_sdma_pkt *pkt,
                                  const struct iovec *iov,
                                  unsigned long niov)
{
        int ret = 0;
        struct page *page = alloc_page(GFP_KERNEL);
        void *mpage_save;
        char *mpage;
        int i;
        int len = 0;
        dma_addr_t dma_addr;

        if (!page) {
                ret = -ENOMEM;
                goto done;
        }

        mpage = kmap(page);
        mpage_save = mpage;
        for (i = 0; i < niov; i++) {
                int cfur;

                cfur = copy_from_user(mpage,
                                      iov[i].iov_base, iov[i].iov_len);
                if (cfur) {
                        ret = -EFAULT;
                        goto free_unmap;
                }

                mpage += iov[i].iov_len;
                len += iov[i].iov_len;
        }

        dma_addr = dma_map_page(&dd->pcidev->dev, page, 0, len,
                                DMA_TO_DEVICE);
        if (dma_mapping_error(&dd->pcidev->dev, dma_addr)) {
                ret = -ENOMEM;
                goto free_unmap;
        }

        qib_user_sdma_init_frag(pkt, 1, 0, len, 0, 1, page, mpage_save,
                                dma_addr);
        pkt->naddr = 2;

        goto done;

free_unmap:
        kunmap(page);
        __free_page(page);
done:
        return ret;
}

/*
 * How many pages in this iovec element?
 */
static int qib_user_sdma_num_pages(const struct iovec *iov)
{
        const unsigned long addr  = (unsigned long) iov->iov_base;
        const unsigned long  len  = iov->iov_len;
        const unsigned long spage = addr & PAGE_MASK;
        const unsigned long epage = (addr + len - 1) & PAGE_MASK;

        return 1 + ((epage - spage) >> PAGE_SHIFT);
}

/*
 * Truncate length to page boundary.
 */
static int qib_user_sdma_page_length(unsigned long addr, unsigned long len)
{
        const unsigned long offset = addr & ~PAGE_MASK;

        return ((offset + len) > PAGE_SIZE) ? (PAGE_SIZE - offset) : len;
}

static void qib_user_sdma_free_pkt_frag(struct device *dev,
                                        struct qib_user_sdma_queue *pq,
                                        struct qib_user_sdma_pkt *pkt,
                                        int frag)
{
        const int i = frag;

        if (pkt->addr[i].page) {
                if (pkt->addr[i].dma_mapped)
                        dma_unmap_page(dev,
                                       pkt->addr[i].addr,
                                       pkt->addr[i].length,
                                       DMA_TO_DEVICE);

                if (pkt->addr[i].kvaddr)
                        kunmap(pkt->addr[i].page);

                if (pkt->addr[i].put_page)
                        put_page(pkt->addr[i].page);
                else
                        __free_page(pkt->addr[i].page);
        } else if (pkt->addr[i].kvaddr)
                /* free coherent mem from cache... */
                dma_pool_free(pq->header_cache,
                              pkt->addr[i].kvaddr, pkt->addr[i].addr);
}

/* return number of pages pinned... */
static int qib_user_sdma_pin_pages(const struct qib_devdata *dd,
                                   struct qib_user_sdma_pkt *pkt,
                                   unsigned long addr, int tlen, int npages)
{
        struct page *pages[2];
        int j;
        int ret;

        ret = get_user_pages(current, current->mm, addr,
                             npages, 0, 1, pages, NULL);

        if (ret != npages) {
                int i;

                for (i = 0; i < ret; i++)
                        put_page(pages[i]);

                ret = -ENOMEM;
                goto done;
        }

        for (j = 0; j < npages; j++) {
                /* map the pages... */
                const int flen = qib_user_sdma_page_length(addr, tlen);
                dma_addr_t dma_addr =
                        dma_map_page(&dd->pcidev->dev,
                                     pages[j], 0, flen, DMA_TO_DEVICE);
                unsigned long fofs = addr & ~PAGE_MASK;

                if (dma_mapping_error(&dd->pcidev->dev, dma_addr)) {
                        ret = -ENOMEM;
                        goto done;
                }

                qib_user_sdma_init_frag(pkt, pkt->naddr, fofs, flen, 1, 1,
                                        pages[j], kmap(pages[j]), dma_addr);

                pkt->naddr++;
                addr += flen;
                tlen -= flen;
        }

done:
        return ret;
}

static int qib_user_sdma_pin_pkt(const struct qib_devdata *dd,
                                 struct qib_user_sdma_queue *pq,
                                 struct qib_user_sdma_pkt *pkt,
                                 const struct iovec *iov,
                                 unsigned long niov)
{
        int ret = 0;
        unsigned long idx;

        for (idx = 0; idx < niov; idx++) {
                const int npages = qib_user_sdma_num_pages(iov + idx);
                const unsigned long addr = (unsigned long) iov[idx].iov_base;

                ret = qib_user_sdma_pin_pages(dd, pkt, addr,
                                              iov[idx].iov_len, npages);
                if (ret < 0)
                        goto free_pkt;
        }

        goto done;

free_pkt:
        for (idx = 0; idx < pkt->naddr; idx++)
                qib_user_sdma_free_pkt_frag(&dd->pcidev->dev, pq, pkt, idx);

done:
        return ret;
}

static int qib_user_sdma_init_payload(const struct qib_devdata *dd,
                                      struct qib_user_sdma_queue *pq,
                                      struct qib_user_sdma_pkt *pkt,
                                      const struct iovec *iov,
                                      unsigned long niov, int npages)
{
        int ret = 0;

        if (npages >= ARRAY_SIZE(pkt->addr))
                ret = qib_user_sdma_coalesce(dd, pkt, iov, niov);
        else
                ret = qib_user_sdma_pin_pkt(dd, pq, pkt, iov, niov);

        return ret;
}

/* free a packet list -- return counter value of last packet */
static void qib_user_sdma_free_pkt_list(struct device *dev,
                                        struct qib_user_sdma_queue *pq,
                                        struct list_head *list)
{
        struct qib_user_sdma_pkt *pkt, *pkt_next;

        list_for_each_entry_safe(pkt, pkt_next, list, list) {
                int i;

                for (i = 0; i < pkt->naddr; i++)
                        qib_user_sdma_free_pkt_frag(dev, pq, pkt, i);

                kmem_cache_free(pq->pkt_slab, pkt);
        }
        INIT_LIST_HEAD(list);
}

/*
 * copy headers, coalesce etc -- pq->lock must be held
 *
 * we queue all the packets to list, returning the
 * number of bytes total.  list must be empty initially,
 * as, if there is an error we clean it...
 */
static int qib_user_sdma_queue_pkts(const struct qib_devdata *dd,
                                    struct qib_user_sdma_queue *pq,
                                    struct list_head *list,
                                    const struct iovec *iov,
                                    unsigned long niov,
                                    int maxpkts)
{
        unsigned long idx = 0;
        int ret = 0;
        int npkts = 0;
        struct page *page = NULL;
        __le32 *pbc;
        dma_addr_t dma_addr;
        struct qib_user_sdma_pkt *pkt = NULL;
        size_t len;
        size_t nw;
        u32 counter = pq->counter;
        int dma_mapped = 0;

        while (idx < niov && npkts < maxpkts) {
                const unsigned long addr = (unsigned long) iov[idx].iov_base;
                const unsigned long idx_save = idx;
                unsigned pktnw;
                unsigned pktnwc;
                int nfrags = 0;
                int npages = 0;
                int cfur;

                dma_mapped = 0;
                len = iov[idx].iov_len;
                nw = len >> 2;
                page = NULL;

                pkt = kmem_cache_alloc(pq->pkt_slab, GFP_KERNEL);
                if (!pkt) {
                        ret = -ENOMEM;
                        goto free_list;
                }

                if (len < QIB_USER_SDMA_MIN_HEADER_LENGTH ||
                    len > PAGE_SIZE || len & 3 || addr & 3) {
                        ret = -EINVAL;
                        goto free_pkt;
                }

                if (len == QIB_USER_SDMA_EXP_HEADER_LENGTH)
                        pbc = dma_pool_alloc(pq->header_cache, GFP_KERNEL,
                                             &dma_addr);
                else
                        pbc = NULL;

                if (!pbc) {
                        page = alloc_page(GFP_KERNEL);
                        if (!page) {
                                ret = -ENOMEM;
                                goto free_pkt;
                        }
                        pbc = kmap(page);
                }

                cfur = copy_from_user(pbc, iov[idx].iov_base, len);
                if (cfur) {
                        ret = -EFAULT;
                        goto free_pbc;
                }

                /*
                 * This assignment is a bit strange.  it's because the
                 * the pbc counts the number of 32 bit words in the full
                 * packet _except_ the first word of the pbc itself...
                 */
                pktnwc = nw - 1;

                /*
                 * pktnw computation yields the number of 32 bit words
                 * that the caller has indicated in the PBC.  note that
                 * this is one less than the total number of words that
                 * goes to the send DMA engine as the first 32 bit word
                 * of the PBC itself is not counted.  Armed with this count,
                 * we can verify that the packet is consistent with the
                 * iovec lengths.
                 */
                pktnw = le32_to_cpu(*pbc) & QIB_PBC_LENGTH_MASK;
                if (pktnw < pktnwc || pktnw > pktnwc + (PAGE_SIZE >> 2)) {
                        ret = -EINVAL;
                        goto free_pbc;
                }

                idx++;
                while (pktnwc < pktnw && idx < niov) {
                        const size_t slen = iov[idx].iov_len;
                        const unsigned long faddr =
                                (unsigned long) iov[idx].iov_base;

                        if (slen & 3 || faddr & 3 || !slen ||
                            slen > PAGE_SIZE) {
                                ret = -EINVAL;
                                goto free_pbc;
                        }

                        npages++;
                        if ((faddr & PAGE_MASK) !=
                            ((faddr + slen - 1) & PAGE_MASK))
                                npages++;

                        pktnwc += slen >> 2;
                        idx++;
                        nfrags++;
                }

                if (pktnwc != pktnw) {
                        ret = -EINVAL;
                        goto free_pbc;
                }

                if (page) {
                        dma_addr = dma_map_page(&dd->pcidev->dev,
                                                page, 0, len, DMA_TO_DEVICE);
                        if (dma_mapping_error(&dd->pcidev->dev, dma_addr)) {
                                ret = -ENOMEM;
                                goto free_pbc;
                        }

                        dma_mapped = 1;
                }

                qib_user_sdma_init_header(pkt, counter, 0, len, dma_mapped,
                                          page, pbc, dma_addr);

                if (nfrags) {
                        ret = qib_user_sdma_init_payload(dd, pq, pkt,
                                                         iov + idx_save + 1,
                                                         nfrags, npages);
                        if (ret < 0)
                                goto free_pbc_dma;
                }

                counter++;
                npkts++;

                list_add_tail(&pkt->list, list);
        }

        ret = idx;
        goto done;

free_pbc_dma:
        if (dma_mapped)
                dma_unmap_page(&dd->pcidev->dev, dma_addr, len, DMA_TO_DEVICE);
free_pbc:
        if (page) {
                kunmap(page);
                __free_page(page);
        } else
                dma_pool_free(pq->header_cache, pbc, dma_addr);
free_pkt:
        kmem_cache_free(pq->pkt_slab, pkt);
free_list:
        qib_user_sdma_free_pkt_list(&dd->pcidev->dev, pq, list);
done:
        return ret;
}

static void qib_user_sdma_set_complete_counter(struct qib_user_sdma_queue *pq,
                                               u32 c)
{
        pq->sent_counter = c;
}

/* try to clean out queue -- needs pq->lock */
static int qib_user_sdma_queue_clean(struct qib_pportdata *ppd,
                                     struct qib_user_sdma_queue *pq)
{
        struct qib_devdata *dd = ppd->dd;
        struct list_head free_list;
        struct qib_user_sdma_pkt *pkt;
        struct qib_user_sdma_pkt *pkt_prev;
        int ret = 0;

        INIT_LIST_HEAD(&free_list);

        list_for_each_entry_safe(pkt, pkt_prev, &pq->sent, list) {
                s64 descd = ppd->sdma_descq_removed - pkt->added;

                if (descd < 0)
                        break;

                list_move_tail(&pkt->list, &free_list);

                /* one more packet cleaned */
                ret++;
        }

        if (!list_empty(&free_list)) {
                u32 counter;

                pkt = list_entry(free_list.prev,
                                 struct qib_user_sdma_pkt, list);
                counter = pkt->counter;

                qib_user_sdma_free_pkt_list(&dd->pcidev->dev, pq, &free_list);
                qib_user_sdma_set_complete_counter(pq, counter);
        }

        return ret;
}

void qib_user_sdma_queue_destroy(struct qib_user_sdma_queue *pq)
{
        if (!pq)
                return;

        kmem_cache_destroy(pq->pkt_slab);
        dma_pool_destroy(pq->header_cache);
        kfree(pq);
}

/* clean descriptor queue, returns > 0 if some elements cleaned */
static int qib_user_sdma_hwqueue_clean(struct qib_pportdata *ppd)
{
        int ret;
        unsigned long flags;

        spin_lock_irqsave(&ppd->sdma_lock, flags);
        ret = qib_sdma_make_progress(ppd);
        spin_unlock_irqrestore(&ppd->sdma_lock, flags);

        return ret;
}

/* we're in close, drain packets so that we can cleanup successfully... */
void qib_user_sdma_queue_drain(struct qib_pportdata *ppd,
                               struct qib_user_sdma_queue *pq)
{
        struct qib_devdata *dd = ppd->dd;
        int i;

        if (!pq)
                return;

        for (i = 0; i < QIB_USER_SDMA_DRAIN_TIMEOUT; i++) {
                mutex_lock(&pq->lock);
                if (list_empty(&pq->sent)) {
                        mutex_unlock(&pq->lock);
                        break;
                }
                qib_user_sdma_hwqueue_clean(ppd);
                qib_user_sdma_queue_clean(ppd, pq);
                mutex_unlock(&pq->lock);
                msleep(10);
        }

        if (!list_empty(&pq->sent)) {
                struct list_head free_list;

                qib_dev_err(dd, "user sdma lists not empty: forcing!\n");
                INIT_LIST_HEAD(&free_list);
                mutex_lock(&pq->lock);
                list_splice_init(&pq->sent, &free_list);
                qib_user_sdma_free_pkt_list(&dd->pcidev->dev, pq, &free_list);
                mutex_unlock(&pq->lock);
        }
}

static inline __le64 qib_sdma_make_desc0(struct qib_pportdata *ppd,
                                         u64 addr, u64 dwlen, u64 dwoffset)
{
        u8 tmpgen;

        tmpgen = ppd->sdma_generation;

        return cpu_to_le64(/* SDmaPhyAddr[31:0] */
                           ((addr & 0xfffffffcULL) << 32) |
                           /* SDmaGeneration[1:0] */
                           ((tmpgen & 3ULL) << 30) |
                           /* SDmaDwordCount[10:0] */
                           ((dwlen & 0x7ffULL) << 16) |
                           /* SDmaBufOffset[12:2] */
                           (dwoffset & 0x7ffULL));
}

static inline __le64 qib_sdma_make_first_desc0(__le64 descq)
{
        return descq | cpu_to_le64(1ULL << 12);
}

static inline __le64 qib_sdma_make_last_desc0(__le64 descq)
{
                                              /* last */  /* dma head */
        return descq | cpu_to_le64(1ULL << 11 | 1ULL << 13);
}

static inline __le64 qib_sdma_make_desc1(u64 addr)
{
        /* SDmaPhyAddr[47:32] */
        return cpu_to_le64(addr >> 32);
}

static void qib_user_sdma_send_frag(struct qib_pportdata *ppd,
                                    struct qib_user_sdma_pkt *pkt, int idx,
                                    unsigned ofs, u16 tail)
{
        const u64 addr = (u64) pkt->addr[idx].addr +
                (u64) pkt->addr[idx].offset;
        const u64 dwlen = (u64) pkt->addr[idx].length / 4;
        __le64 *descqp;
        __le64 descq0;

        descqp = &ppd->sdma_descq[tail].qw[0];

        descq0 = qib_sdma_make_desc0(ppd, addr, dwlen, ofs);
        if (idx == 0)
                descq0 = qib_sdma_make_first_desc0(descq0);
        if (idx == pkt->naddr - 1)
                descq0 = qib_sdma_make_last_desc0(descq0);

        descqp[0] = descq0;
        descqp[1] = qib_sdma_make_desc1(addr);
}

/* pq->lock must be held, get packets on the wire... */
static int qib_user_sdma_push_pkts(struct qib_pportdata *ppd,
                                   struct qib_user_sdma_queue *pq,
                                   struct list_head *pktlist)
{
        struct qib_devdata *dd = ppd->dd;
        int ret = 0;
        unsigned long flags;
        u16 tail;
        u8 generation;
        u64 descq_added;

        if (list_empty(pktlist))
                return 0;

        if (unlikely(!(ppd->lflags & QIBL_LINKACTIVE)))
                return -ECOMM;

        spin_lock_irqsave(&ppd->sdma_lock, flags);

        /* keep a copy for restoring purposes in case of problems */
        generation = ppd->sdma_generation;
        descq_added = ppd->sdma_descq_added;

        if (unlikely(!__qib_sdma_running(ppd))) {
                ret = -ECOMM;
                goto unlock;
        }

        tail = ppd->sdma_descq_tail;
        while (!list_empty(pktlist)) {
                struct qib_user_sdma_pkt *pkt =
                        list_entry(pktlist->next, struct qib_user_sdma_pkt,
                                   list);
                int i;
                unsigned ofs = 0;
                u16 dtail = tail;

                if (pkt->naddr > qib_sdma_descq_freecnt(ppd))
                        goto unlock_check_tail;

                for (i = 0; i < pkt->naddr; i++) {
                        qib_user_sdma_send_frag(ppd, pkt, i, ofs, tail);
                        ofs += pkt->addr[i].length >> 2;

                        if (++tail == ppd->sdma_descq_cnt) {
                                tail = 0;
                                ++ppd->sdma_generation;
                        }
                }

                if ((ofs << 2) > ppd->ibmaxlen) {
                        ret = -EMSGSIZE;
                        goto unlock;
                }

                /*
                 * If the packet is >= 2KB mtu equivalent, we have to use
                 * the large buffers, and have to mark each descriptor as
                 * part of a large buffer packet.
                 */
                if (ofs > dd->piosize2kmax_dwords) {
                        for (i = 0; i < pkt->naddr; i++) {
                                ppd->sdma_descq[dtail].qw[0] |=
                                        cpu_to_le64(1ULL << 14);
                                if (++dtail == ppd->sdma_descq_cnt)
                                        dtail = 0;
                        }
                }

                ppd->sdma_descq_added += pkt->naddr;
                pkt->added = ppd->sdma_descq_added;
                list_move_tail(&pkt->list, &pq->sent);
                ret++;
        }

unlock_check_tail:
        /* advance the tail on the chip if necessary */
        if (ppd->sdma_descq_tail != tail)
                dd->f_sdma_update_tail(ppd, tail);

unlock:
        if (unlikely(ret < 0)) {
                ppd->sdma_generation = generation;
                ppd->sdma_descq_added = descq_added;
        }
        spin_unlock_irqrestore(&ppd->sdma_lock, flags);

        return ret;
}

int qib_user_sdma_writev(struct qib_ctxtdata *rcd,
                         struct qib_user_sdma_queue *pq,
                         const struct iovec *iov,
                         unsigned long dim)
{
        struct qib_devdata *dd = rcd->dd;
        struct qib_pportdata *ppd = rcd->ppd;
        int ret = 0;
        struct list_head list;
        int npkts = 0;

        INIT_LIST_HEAD(&list);

        mutex_lock(&pq->lock);

        /* why not -ECOMM like qib_user_sdma_push_pkts() below? */
        if (!qib_sdma_running(ppd))
                goto done_unlock;

        if (ppd->sdma_descq_added != ppd->sdma_descq_removed) {
                qib_user_sdma_hwqueue_clean(ppd);
                qib_user_sdma_queue_clean(ppd, pq);
        }

        while (dim) {
                const int mxp = 8;

                down_write(&current->mm->mmap_sem);
                ret = qib_user_sdma_queue_pkts(dd, pq, &list, iov, dim, mxp);
                up_write(&current->mm->mmap_sem);

                if (ret <= 0)
                        goto done_unlock;
                else {
                        dim -= ret;
                        iov += ret;
                }

                /* force packets onto the sdma hw queue... */
                if (!list_empty(&list)) {
                        /*
                         * Lazily clean hw queue.  the 4 is a guess of about
                         * how many sdma descriptors a packet will take (it
                         * doesn't have to be perfect).
                         */
                        if (qib_sdma_descq_freecnt(ppd) < ret * 4) {
                                qib_user_sdma_hwqueue_clean(ppd);
                                qib_user_sdma_queue_clean(ppd, pq);
                        }

                        ret = qib_user_sdma_push_pkts(ppd, pq, &list);
                        if (ret < 0)
                                goto done_unlock;
                        else {
                                npkts += ret;
                                pq->counter += ret;

                                if (!list_empty(&list))
                                        goto done_unlock;
                        }
                }
        }

done_unlock:
        if (!list_empty(&list))
                qib_user_sdma_free_pkt_list(&dd->pcidev->dev, pq, &list);
        mutex_unlock(&pq->lock);

        return (ret < 0) ? ret : npkts;
}

int qib_user_sdma_make_progress(struct qib_pportdata *ppd,
                                struct qib_user_sdma_queue *pq)
{
        int ret = 0;

        mutex_lock(&pq->lock);
        qib_user_sdma_hwqueue_clean(ppd);
        ret = qib_user_sdma_queue_clean(ppd, pq);
        mutex_unlock(&pq->lock);

        return ret;
}

u32 qib_user_sdma_complete_counter(const struct qib_user_sdma_queue *pq)
{
        return pq ? pq->sent_counter : 0;
}

u32 qib_user_sdma_inflight_counter(struct qib_user_sdma_queue *pq)
{
        return pq ? pq->counter : 0;
}