Add linux-next specific files for 20110831

[linux-2.6/next.git] / drivers / infiniband / hw / qib / qib_file_ops.c

/*
 * Copyright (c) 2006, 2007, 2008, 2009, 2010 QLogic Corporation.
 * All rights reserved.
 * Copyright (c) 2003, 2004, 2005, 2006 PathScale, 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/pci.h>
#include <linux/poll.h>
#include <linux/cdev.h>
#include <linux/swap.h>
#include <linux/vmalloc.h>
#include <linux/highmem.h>
#include <linux/io.h>
#include <linux/uio.h>
#include <linux/jiffies.h>
#include <asm/pgtable.h>
#include <linux/delay.h>
#include <linux/export.h>

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

static int qib_open(struct inode *, struct file *);
static int qib_close(struct inode *, struct file *);
static ssize_t qib_write(struct file *, const char __user *, size_t, loff_t *);
static ssize_t qib_aio_write(struct kiocb *, const struct iovec *,
                             unsigned long, loff_t);
static unsigned int qib_poll(struct file *, struct poll_table_struct *);
static int qib_mmapf(struct file *, struct vm_area_struct *);

static const struct file_operations qib_file_ops = {
        .owner = THIS_MODULE,
        .write = qib_write,
        .aio_write = qib_aio_write,
        .open = qib_open,
        .release = qib_close,
        .poll = qib_poll,
        .mmap = qib_mmapf,
        .llseek = noop_llseek,
};

/*
 * Convert kernel virtual addresses to physical addresses so they don't
 * potentially conflict with the chip addresses used as mmap offsets.
 * It doesn't really matter what mmap offset we use as long as we can
 * interpret it correctly.
 */
static u64 cvt_kvaddr(void *p)
{
        struct page *page;
        u64 paddr = 0;

        page = vmalloc_to_page(p);
        if (page)
                paddr = page_to_pfn(page) << PAGE_SHIFT;

        return paddr;
}

static int qib_get_base_info(struct file *fp, void __user *ubase,
                             size_t ubase_size)
{
        struct qib_ctxtdata *rcd = ctxt_fp(fp);
        int ret = 0;
        struct qib_base_info *kinfo = NULL;
        struct qib_devdata *dd = rcd->dd;
        struct qib_pportdata *ppd = rcd->ppd;
        unsigned subctxt_cnt;
        int shared, master;
        size_t sz;

        subctxt_cnt = rcd->subctxt_cnt;
        if (!subctxt_cnt) {
                shared = 0;
                master = 0;
                subctxt_cnt = 1;
        } else {
                shared = 1;
                master = !subctxt_fp(fp);
        }

        sz = sizeof(*kinfo);
        /* If context sharing is not requested, allow the old size structure */
        if (!shared)
                sz -= 7 * sizeof(u64);
        if (ubase_size < sz) {
                ret = -EINVAL;
                goto bail;
        }

        kinfo = kzalloc(sizeof(*kinfo), GFP_KERNEL);
        if (kinfo == NULL) {
                ret = -ENOMEM;
                goto bail;
        }

        ret = dd->f_get_base_info(rcd, kinfo);
        if (ret < 0)
                goto bail;

        kinfo->spi_rcvhdr_cnt = dd->rcvhdrcnt;
        kinfo->spi_rcvhdrent_size = dd->rcvhdrentsize;
        kinfo->spi_tidegrcnt = rcd->rcvegrcnt;
        kinfo->spi_rcv_egrbufsize = dd->rcvegrbufsize;
        /*
         * have to mmap whole thing
         */
        kinfo->spi_rcv_egrbuftotlen =
                rcd->rcvegrbuf_chunks * rcd->rcvegrbuf_size;
        kinfo->spi_rcv_egrperchunk = rcd->rcvegrbufs_perchunk;
        kinfo->spi_rcv_egrchunksize = kinfo->spi_rcv_egrbuftotlen /
                rcd->rcvegrbuf_chunks;
        kinfo->spi_tidcnt = dd->rcvtidcnt / subctxt_cnt;
        if (master)
                kinfo->spi_tidcnt += dd->rcvtidcnt % subctxt_cnt;
        /*
         * for this use, may be cfgctxts summed over all chips that
         * are are configured and present
         */
        kinfo->spi_nctxts = dd->cfgctxts;
        /* unit (chip/board) our context is on */
        kinfo->spi_unit = dd->unit;
        kinfo->spi_port = ppd->port;
        /* for now, only a single page */
        kinfo->spi_tid_maxsize = PAGE_SIZE;

        /*
         * Doing this per context, and based on the skip value, etc.  This has
         * to be the actual buffer size, since the protocol code treats it
         * as an array.
         *
         * These have to be set to user addresses in the user code via mmap.
         * These values are used on return to user code for the mmap target
         * addresses only.  For 32 bit, same 44 bit address problem, so use
         * the physical address, not virtual.  Before 2.6.11, using the
         * page_address() macro worked, but in 2.6.11, even that returns the
         * full 64 bit address (upper bits all 1's).  So far, using the
         * physical addresses (or chip offsets, for chip mapping) works, but
         * no doubt some future kernel release will change that, and we'll be
         * on to yet another method of dealing with this.
         * Normally only one of rcvhdr_tailaddr or rhf_offset is useful
         * since the chips with non-zero rhf_offset don't normally
         * enable tail register updates to host memory, but for testing,
         * both can be enabled and used.
         */
        kinfo->spi_rcvhdr_base = (u64) rcd->rcvhdrq_phys;
        kinfo->spi_rcvhdr_tailaddr = (u64) rcd->rcvhdrqtailaddr_phys;
        kinfo->spi_rhf_offset = dd->rhf_offset;
        kinfo->spi_rcv_egrbufs = (u64) rcd->rcvegr_phys;
        kinfo->spi_pioavailaddr = (u64) dd->pioavailregs_phys;
        /* setup per-unit (not port) status area for user programs */
        kinfo->spi_status = (u64) kinfo->spi_pioavailaddr +
                (char *) ppd->statusp -
                (char *) dd->pioavailregs_dma;
        kinfo->spi_uregbase = (u64) dd->uregbase + dd->ureg_align * rcd->ctxt;
        if (!shared) {
                kinfo->spi_piocnt = rcd->piocnt;
                kinfo->spi_piobufbase = (u64) rcd->piobufs;
                kinfo->spi_sendbuf_status = cvt_kvaddr(rcd->user_event_mask);
        } else if (master) {
                kinfo->spi_piocnt = (rcd->piocnt / subctxt_cnt) +
                                    (rcd->piocnt % subctxt_cnt);
                /* Master's PIO buffers are after all the slave's */
                kinfo->spi_piobufbase = (u64) rcd->piobufs +
                        dd->palign *
                        (rcd->piocnt - kinfo->spi_piocnt);
        } else {
                unsigned slave = subctxt_fp(fp) - 1;

                kinfo->spi_piocnt = rcd->piocnt / subctxt_cnt;
                kinfo->spi_piobufbase = (u64) rcd->piobufs +
                        dd->palign * kinfo->spi_piocnt * slave;
        }

        if (shared) {
                kinfo->spi_sendbuf_status =
                        cvt_kvaddr(&rcd->user_event_mask[subctxt_fp(fp)]);
                /* only spi_subctxt_* fields should be set in this block! */
                kinfo->spi_subctxt_uregbase = cvt_kvaddr(rcd->subctxt_uregbase);

                kinfo->spi_subctxt_rcvegrbuf =
                        cvt_kvaddr(rcd->subctxt_rcvegrbuf);
                kinfo->spi_subctxt_rcvhdr_base =
                        cvt_kvaddr(rcd->subctxt_rcvhdr_base);
        }

        /*
         * All user buffers are 2KB buffers.  If we ever support
         * giving 4KB buffers to user processes, this will need some
         * work.  Can't use piobufbase directly, because it has
         * both 2K and 4K buffer base values.
         */
        kinfo->spi_pioindex = (kinfo->spi_piobufbase - dd->pio2k_bufbase) /
                dd->palign;
        kinfo->spi_pioalign = dd->palign;
        kinfo->spi_qpair = QIB_KD_QP;
        /*
         * user mode PIO buffers are always 2KB, even when 4KB can
         * be received, and sent via the kernel; this is ibmaxlen
         * for 2K MTU.
         */
        kinfo->spi_piosize = dd->piosize2k - 2 * sizeof(u32);
        kinfo->spi_mtu = ppd->ibmaxlen; /* maxlen, not ibmtu */
        kinfo->spi_ctxt = rcd->ctxt;
        kinfo->spi_subctxt = subctxt_fp(fp);
        kinfo->spi_sw_version = QIB_KERN_SWVERSION;
        kinfo->spi_sw_version |= 1U << 31; /* QLogic-built, not kernel.org */
        kinfo->spi_hw_version = dd->revision;

        if (master)
                kinfo->spi_runtime_flags |= QIB_RUNTIME_MASTER;

        sz = (ubase_size < sizeof(*kinfo)) ? ubase_size : sizeof(*kinfo);
        if (copy_to_user(ubase, kinfo, sz))
                ret = -EFAULT;
bail:
        kfree(kinfo);
        return ret;
}

/**
 * qib_tid_update - update a context TID
 * @rcd: the context
 * @fp: the qib device file
 * @ti: the TID information
 *
 * The new implementation as of Oct 2004 is that the driver assigns
 * the tid and returns it to the caller.   To reduce search time, we
 * keep a cursor for each context, walking the shadow tid array to find
 * one that's not in use.
 *
 * For now, if we can't allocate the full list, we fail, although
 * in the long run, we'll allocate as many as we can, and the
 * caller will deal with that by trying the remaining pages later.
 * That means that when we fail, we have to mark the tids as not in
 * use again, in our shadow copy.
 *
 * It's up to the caller to free the tids when they are done.
 * We'll unlock the pages as they free them.
 *
 * Also, right now we are locking one page at a time, but since
 * the intended use of this routine is for a single group of
 * virtually contiguous pages, that should change to improve
 * performance.
 */
static int qib_tid_update(struct qib_ctxtdata *rcd, struct file *fp,
                          const struct qib_tid_info *ti)
{
        int ret = 0, ntids;
        u32 tid, ctxttid, cnt, i, tidcnt, tidoff;
        u16 *tidlist;
        struct qib_devdata *dd = rcd->dd;
        u64 physaddr;
        unsigned long vaddr;
        u64 __iomem *tidbase;
        unsigned long tidmap[8];
        struct page **pagep = NULL;
        unsigned subctxt = subctxt_fp(fp);

        if (!dd->pageshadow) {
                ret = -ENOMEM;
                goto done;
        }

        cnt = ti->tidcnt;
        if (!cnt) {
                ret = -EFAULT;
                goto done;
        }
        ctxttid = rcd->ctxt * dd->rcvtidcnt;
        if (!rcd->subctxt_cnt) {
                tidcnt = dd->rcvtidcnt;
                tid = rcd->tidcursor;
                tidoff = 0;
        } else if (!subctxt) {
                tidcnt = (dd->rcvtidcnt / rcd->subctxt_cnt) +
                         (dd->rcvtidcnt % rcd->subctxt_cnt);
                tidoff = dd->rcvtidcnt - tidcnt;
                ctxttid += tidoff;
                tid = tidcursor_fp(fp);
        } else {
                tidcnt = dd->rcvtidcnt / rcd->subctxt_cnt;
                tidoff = tidcnt * (subctxt - 1);
                ctxttid += tidoff;
                tid = tidcursor_fp(fp);
        }
        if (cnt > tidcnt) {
                /* make sure it all fits in tid_pg_list */
                qib_devinfo(dd->pcidev, "Process tried to allocate %u "
                         "TIDs, only trying max (%u)\n", cnt, tidcnt);
                cnt = tidcnt;
        }
        pagep = (struct page **) rcd->tid_pg_list;
        tidlist = (u16 *) &pagep[dd->rcvtidcnt];
        pagep += tidoff;
        tidlist += tidoff;

        memset(tidmap, 0, sizeof(tidmap));
        /* before decrement; chip actual # */
        ntids = tidcnt;
        tidbase = (u64 __iomem *) (((char __iomem *) dd->kregbase) +
                                   dd->rcvtidbase +
                                   ctxttid * sizeof(*tidbase));

        /* virtual address of first page in transfer */
        vaddr = ti->tidvaddr;
        if (!access_ok(VERIFY_WRITE, (void __user *) vaddr,
                       cnt * PAGE_SIZE)) {
                ret = -EFAULT;
                goto done;
        }
        ret = qib_get_user_pages(vaddr, cnt, pagep);
        if (ret) {
                /*
                 * if (ret == -EBUSY)
                 * We can't continue because the pagep array won't be
                 * initialized. This should never happen,
                 * unless perhaps the user has mpin'ed the pages
                 * themselves.
                 */
                qib_devinfo(dd->pcidev,
                         "Failed to lock addr %p, %u pages: "
                         "errno %d\n", (void *) vaddr, cnt, -ret);
                goto done;
        }
        for (i = 0; i < cnt; i++, vaddr += PAGE_SIZE) {
                for (; ntids--; tid++) {
                        if (tid == tidcnt)
                                tid = 0;
                        if (!dd->pageshadow[ctxttid + tid])
                                break;
                }
                if (ntids < 0) {
                        /*
                         * Oops, wrapped all the way through their TIDs,
                         * and didn't have enough free; see comments at
                         * start of routine
                         */
                        i--;    /* last tidlist[i] not filled in */
                        ret = -ENOMEM;
                        break;
                }
                tidlist[i] = tid + tidoff;
                /* we "know" system pages and TID pages are same size */
                dd->pageshadow[ctxttid + tid] = pagep[i];
                dd->physshadow[ctxttid + tid] =
                        qib_map_page(dd->pcidev, pagep[i], 0, PAGE_SIZE,
                                     PCI_DMA_FROMDEVICE);
                /*
                 * don't need atomic or it's overhead
                 */
                __set_bit(tid, tidmap);
                physaddr = dd->physshadow[ctxttid + tid];
                /* PERFORMANCE: below should almost certainly be cached */
                dd->f_put_tid(dd, &tidbase[tid],
                                  RCVHQ_RCV_TYPE_EXPECTED, physaddr);
                /*
                 * don't check this tid in qib_ctxtshadow, since we
                 * just filled it in; start with the next one.
                 */
                tid++;
        }

        if (ret) {
                u32 limit;
cleanup:
                /* jump here if copy out of updated info failed... */
                /* same code that's in qib_free_tid() */
                limit = sizeof(tidmap) * BITS_PER_BYTE;
                if (limit > tidcnt)
                        /* just in case size changes in future */
                        limit = tidcnt;
                tid = find_first_bit((const unsigned long *)tidmap, limit);
                for (; tid < limit; tid++) {
                        if (!test_bit(tid, tidmap))
                                continue;
                        if (dd->pageshadow[ctxttid + tid]) {
                                dma_addr_t phys;

                                phys = dd->physshadow[ctxttid + tid];
                                dd->physshadow[ctxttid + tid] = dd->tidinvalid;
                                /* PERFORMANCE: below should almost certainly
                                 * be cached
                                 */
                                dd->f_put_tid(dd, &tidbase[tid],
                                              RCVHQ_RCV_TYPE_EXPECTED,
                                              dd->tidinvalid);
                                pci_unmap_page(dd->pcidev, phys, PAGE_SIZE,
                                               PCI_DMA_FROMDEVICE);
                                dd->pageshadow[ctxttid + tid] = NULL;
                        }
                }
                qib_release_user_pages(pagep, cnt);
        } else {
                /*
                 * Copy the updated array, with qib_tid's filled in, back
                 * to user.  Since we did the copy in already, this "should
                 * never fail" If it does, we have to clean up...
                 */
                if (copy_to_user((void __user *)
                                 (unsigned long) ti->tidlist,
                                 tidlist, cnt * sizeof(*tidlist))) {
                        ret = -EFAULT;
                        goto cleanup;
                }
                if (copy_to_user((void __user *) (unsigned long) ti->tidmap,
                                 tidmap, sizeof tidmap)) {
                        ret = -EFAULT;
                        goto cleanup;
                }
                if (tid == tidcnt)
                        tid = 0;
                if (!rcd->subctxt_cnt)
                        rcd->tidcursor = tid;
                else
                        tidcursor_fp(fp) = tid;
        }

done:
        return ret;
}

/**
 * qib_tid_free - free a context TID
 * @rcd: the context
 * @subctxt: the subcontext
 * @ti: the TID info
 *
 * right now we are unlocking one page at a time, but since
 * the intended use of this routine is for a single group of
 * virtually contiguous pages, that should change to improve
 * performance.  We check that the TID is in range for this context
 * but otherwise don't check validity; if user has an error and
 * frees the wrong tid, it's only their own data that can thereby
 * be corrupted.  We do check that the TID was in use, for sanity
 * We always use our idea of the saved address, not the address that
 * they pass in to us.
 */
static int qib_tid_free(struct qib_ctxtdata *rcd, unsigned subctxt,
                        const struct qib_tid_info *ti)
{
        int ret = 0;
        u32 tid, ctxttid, cnt, limit, tidcnt;
        struct qib_devdata *dd = rcd->dd;
        u64 __iomem *tidbase;
        unsigned long tidmap[8];

        if (!dd->pageshadow) {
                ret = -ENOMEM;
                goto done;
        }

        if (copy_from_user(tidmap, (void __user *)(unsigned long)ti->tidmap,
                           sizeof tidmap)) {
                ret = -EFAULT;
                goto done;
        }

        ctxttid = rcd->ctxt * dd->rcvtidcnt;
        if (!rcd->subctxt_cnt)
                tidcnt = dd->rcvtidcnt;
        else if (!subctxt) {
                tidcnt = (dd->rcvtidcnt / rcd->subctxt_cnt) +
                         (dd->rcvtidcnt % rcd->subctxt_cnt);
                ctxttid += dd->rcvtidcnt - tidcnt;
        } else {
                tidcnt = dd->rcvtidcnt / rcd->subctxt_cnt;
                ctxttid += tidcnt * (subctxt - 1);
        }
        tidbase = (u64 __iomem *) ((char __iomem *)(dd->kregbase) +
                                   dd->rcvtidbase +
                                   ctxttid * sizeof(*tidbase));

        limit = sizeof(tidmap) * BITS_PER_BYTE;
        if (limit > tidcnt)
                /* just in case size changes in future */
                limit = tidcnt;
        tid = find_first_bit(tidmap, limit);
        for (cnt = 0; tid < limit; tid++) {
                /*
                 * small optimization; if we detect a run of 3 or so without
                 * any set, use find_first_bit again.  That's mainly to
                 * accelerate the case where we wrapped, so we have some at
                 * the beginning, and some at the end, and a big gap
                 * in the middle.
                 */
                if (!test_bit(tid, tidmap))
                        continue;
                cnt++;
                if (dd->pageshadow[ctxttid + tid]) {
                        struct page *p;
                        dma_addr_t phys;

                        p = dd->pageshadow[ctxttid + tid];
                        dd->pageshadow[ctxttid + tid] = NULL;
                        phys = dd->physshadow[ctxttid + tid];
                        dd->physshadow[ctxttid + tid] = dd->tidinvalid;
                        /* PERFORMANCE: below should almost certainly be
                         * cached
                         */
                        dd->f_put_tid(dd, &tidbase[tid],
                                      RCVHQ_RCV_TYPE_EXPECTED, dd->tidinvalid);
                        pci_unmap_page(dd->pcidev, phys, PAGE_SIZE,
                                       PCI_DMA_FROMDEVICE);
                        qib_release_user_pages(&p, 1);
                }
        }
done:
        return ret;
}

/**
 * qib_set_part_key - set a partition key
 * @rcd: the context
 * @key: the key
 *
 * We can have up to 4 active at a time (other than the default, which is
 * always allowed).  This is somewhat tricky, since multiple contexts may set
 * the same key, so we reference count them, and clean up at exit.  All 4
 * partition keys are packed into a single qlogic_ib register.  It's an
 * error for a process to set the same pkey multiple times.  We provide no
 * mechanism to de-allocate a pkey at this time, we may eventually need to
 * do that.  I've used the atomic operations, and no locking, and only make
 * a single pass through what's available.  This should be more than
 * adequate for some time. I'll think about spinlocks or the like if and as
 * it's necessary.
 */
static int qib_set_part_key(struct qib_ctxtdata *rcd, u16 key)
{
        struct qib_pportdata *ppd = rcd->ppd;
        int i, any = 0, pidx = -1;
        u16 lkey = key & 0x7FFF;
        int ret;

        if (lkey == (QIB_DEFAULT_P_KEY & 0x7FFF)) {
                /* nothing to do; this key always valid */
                ret = 0;
                goto bail;
        }

        if (!lkey) {
                ret = -EINVAL;
                goto bail;
        }

        /*
         * Set the full membership bit, because it has to be
         * set in the register or the packet, and it seems
         * cleaner to set in the register than to force all
         * callers to set it.
         */
        key |= 0x8000;

        for (i = 0; i < ARRAY_SIZE(rcd->pkeys); i++) {
                if (!rcd->pkeys[i] && pidx == -1)
                        pidx = i;
                if (rcd->pkeys[i] == key) {
                        ret = -EEXIST;
                        goto bail;
                }
        }
        if (pidx == -1) {
                ret = -EBUSY;
                goto bail;
        }
        for (any = i = 0; i < ARRAY_SIZE(ppd->pkeys); i++) {
                if (!ppd->pkeys[i]) {
                        any++;
                        continue;
                }
                if (ppd->pkeys[i] == key) {
                        atomic_t *pkrefs = &ppd->pkeyrefs[i];

                        if (atomic_inc_return(pkrefs) > 1) {
                                rcd->pkeys[pidx] = key;
                                ret = 0;
                                goto bail;
                        } else {
                                /*
                                 * lost race, decrement count, catch below
                                 */
                                atomic_dec(pkrefs);
                                any++;
                        }
                }
                if ((ppd->pkeys[i] & 0x7FFF) == lkey) {
                        /*
                         * It makes no sense to have both the limited and
                         * full membership PKEY set at the same time since
                         * the unlimited one will disable the limited one.
                         */
                        ret = -EEXIST;
                        goto bail;
                }
        }
        if (!any) {
                ret = -EBUSY;
                goto bail;
        }
        for (any = i = 0; i < ARRAY_SIZE(ppd->pkeys); i++) {
                if (!ppd->pkeys[i] &&
                    atomic_inc_return(&ppd->pkeyrefs[i]) == 1) {
                        rcd->pkeys[pidx] = key;
                        ppd->pkeys[i] = key;
                        (void) ppd->dd->f_set_ib_cfg(ppd, QIB_IB_CFG_PKEYS, 0);
                        ret = 0;
                        goto bail;
                }
        }
        ret = -EBUSY;

bail:
        return ret;
}

/**
 * qib_manage_rcvq - manage a context's receive queue
 * @rcd: the context
 * @subctxt: the subcontext
 * @start_stop: action to carry out
 *
 * start_stop == 0 disables receive on the context, for use in queue
 * overflow conditions.  start_stop==1 re-enables, to be used to
 * re-init the software copy of the head register
 */
static int qib_manage_rcvq(struct qib_ctxtdata *rcd, unsigned subctxt,
                           int start_stop)
{
        struct qib_devdata *dd = rcd->dd;
        unsigned int rcvctrl_op;

        if (subctxt)
                goto bail;
        /* atomically clear receive enable ctxt. */
        if (start_stop) {
                /*
                 * On enable, force in-memory copy of the tail register to
                 * 0, so that protocol code doesn't have to worry about
                 * whether or not the chip has yet updated the in-memory
                 * copy or not on return from the system call. The chip
                 * always resets it's tail register back to 0 on a
                 * transition from disabled to enabled.
                 */
                if (rcd->rcvhdrtail_kvaddr)
                        qib_clear_rcvhdrtail(rcd);
                rcvctrl_op = QIB_RCVCTRL_CTXT_ENB;
        } else
                rcvctrl_op = QIB_RCVCTRL_CTXT_DIS;
        dd->f_rcvctrl(rcd->ppd, rcvctrl_op, rcd->ctxt);
        /* always; new head should be equal to new tail; see above */
bail:
        return 0;
}

static void qib_clean_part_key(struct qib_ctxtdata *rcd,
                               struct qib_devdata *dd)
{
        int i, j, pchanged = 0;
        u64 oldpkey;
        struct qib_pportdata *ppd = rcd->ppd;

        /* for debugging only */
        oldpkey = (u64) ppd->pkeys[0] |
                ((u64) ppd->pkeys[1] << 16) |
                ((u64) ppd->pkeys[2] << 32) |
                ((u64) ppd->pkeys[3] << 48);

        for (i = 0; i < ARRAY_SIZE(rcd->pkeys); i++) {
                if (!rcd->pkeys[i])
                        continue;
                for (j = 0; j < ARRAY_SIZE(ppd->pkeys); j++) {
                        /* check for match independent of the global bit */
                        if ((ppd->pkeys[j] & 0x7fff) !=
                            (rcd->pkeys[i] & 0x7fff))
                                continue;
                        if (atomic_dec_and_test(&ppd->pkeyrefs[j])) {
                                ppd->pkeys[j] = 0;
                                pchanged++;
                        }
                        break;
                }
                rcd->pkeys[i] = 0;
        }
        if (pchanged)
                (void) ppd->dd->f_set_ib_cfg(ppd, QIB_IB_CFG_PKEYS, 0);
}

/* common code for the mappings on dma_alloc_coherent mem */
static int qib_mmap_mem(struct vm_area_struct *vma, struct qib_ctxtdata *rcd,
                        unsigned len, void *kvaddr, u32 write_ok, char *what)
{
        struct qib_devdata *dd = rcd->dd;
        unsigned long pfn;
        int ret;

        if ((vma->vm_end - vma->vm_start) > len) {
                qib_devinfo(dd->pcidev,
                         "FAIL on %s: len %lx > %x\n", what,
                         vma->vm_end - vma->vm_start, len);
                ret = -EFAULT;
                goto bail;
        }

        /*
         * shared context user code requires rcvhdrq mapped r/w, others
         * only allowed readonly mapping.
         */
        if (!write_ok) {
                if (vma->vm_flags & VM_WRITE) {
                        qib_devinfo(dd->pcidev,
                                 "%s must be mapped readonly\n", what);
                        ret = -EPERM;
                        goto bail;
                }

                /* don't allow them to later change with mprotect */
                vma->vm_flags &= ~VM_MAYWRITE;
        }

        pfn = virt_to_phys(kvaddr) >> PAGE_SHIFT;
        ret = remap_pfn_range(vma, vma->vm_start, pfn,
                              len, vma->vm_page_prot);
        if (ret)
                qib_devinfo(dd->pcidev, "%s ctxt%u mmap of %lx, %x "
                         "bytes failed: %d\n", what, rcd->ctxt,
                         pfn, len, ret);
bail:
        return ret;
}

static int mmap_ureg(struct vm_area_struct *vma, struct qib_devdata *dd,
                     u64 ureg)
{
        unsigned long phys;
        unsigned long sz;
        int ret;

        /*
         * This is real hardware, so use io_remap.  This is the mechanism
         * for the user process to update the head registers for their ctxt
         * in the chip.
         */
        sz = dd->flags & QIB_HAS_HDRSUPP ? 2 * PAGE_SIZE : PAGE_SIZE;
        if ((vma->vm_end - vma->vm_start) > sz) {
                qib_devinfo(dd->pcidev, "FAIL mmap userreg: reqlen "
                         "%lx > PAGE\n", vma->vm_end - vma->vm_start);
                ret = -EFAULT;
        } else {
                phys = dd->physaddr + ureg;
                vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

                vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND;
                ret = io_remap_pfn_range(vma, vma->vm_start,
                                         phys >> PAGE_SHIFT,
                                         vma->vm_end - vma->vm_start,
                                         vma->vm_page_prot);
        }
        return ret;
}

static int mmap_piobufs(struct vm_area_struct *vma,
                        struct qib_devdata *dd,
                        struct qib_ctxtdata *rcd,
                        unsigned piobufs, unsigned piocnt)
{
        unsigned long phys;
        int ret;

        /*
         * When we map the PIO buffers in the chip, we want to map them as
         * writeonly, no read possible; unfortunately, x86 doesn't allow
         * for this in hardware, but we still prevent users from asking
         * for it.
         */
        if ((vma->vm_end - vma->vm_start) > (piocnt * dd->palign)) {
                qib_devinfo(dd->pcidev, "FAIL mmap piobufs: "
                         "reqlen %lx > PAGE\n",
                         vma->vm_end - vma->vm_start);
                ret = -EINVAL;
                goto bail;
        }

        phys = dd->physaddr + piobufs;

#if defined(__powerpc__)
        /* There isn't a generic way to specify writethrough mappings */
        pgprot_val(vma->vm_page_prot) |= _PAGE_NO_CACHE;
        pgprot_val(vma->vm_page_prot) |= _PAGE_WRITETHRU;
        pgprot_val(vma->vm_page_prot) &= ~_PAGE_GUARDED;
#endif

        /*
         * don't allow them to later change to readable with mprotect (for when
         * not initially mapped readable, as is normally the case)
         */
        vma->vm_flags &= ~VM_MAYREAD;
        vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND;

        if (qib_wc_pat)
                vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);

        ret = io_remap_pfn_range(vma, vma->vm_start, phys >> PAGE_SHIFT,
                                 vma->vm_end - vma->vm_start,
                                 vma->vm_page_prot);
bail:
        return ret;
}

static int mmap_rcvegrbufs(struct vm_area_struct *vma,
                           struct qib_ctxtdata *rcd)
{
        struct qib_devdata *dd = rcd->dd;
        unsigned long start, size;
        size_t total_size, i;
        unsigned long pfn;
        int ret;

        size = rcd->rcvegrbuf_size;
        total_size = rcd->rcvegrbuf_chunks * size;
        if ((vma->vm_end - vma->vm_start) > total_size) {
                qib_devinfo(dd->pcidev, "FAIL on egr bufs: "
                         "reqlen %lx > actual %lx\n",
                         vma->vm_end - vma->vm_start,
                         (unsigned long) total_size);
                ret = -EINVAL;
                goto bail;
        }

        if (vma->vm_flags & VM_WRITE) {
                qib_devinfo(dd->pcidev, "Can't map eager buffers as "
                         "writable (flags=%lx)\n", vma->vm_flags);
                ret = -EPERM;
                goto bail;
        }
        /* don't allow them to later change to writeable with mprotect */
        vma->vm_flags &= ~VM_MAYWRITE;

        start = vma->vm_start;

        for (i = 0; i < rcd->rcvegrbuf_chunks; i++, start += size) {
                pfn = virt_to_phys(rcd->rcvegrbuf[i]) >> PAGE_SHIFT;
                ret = remap_pfn_range(vma, start, pfn, size,
                                      vma->vm_page_prot);
                if (ret < 0)
                        goto bail;
        }
        ret = 0;

bail:
        return ret;
}

/*
 * qib_file_vma_fault - handle a VMA page fault.
 */
static int qib_file_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct page *page;

        page = vmalloc_to_page((void *)(vmf->pgoff << PAGE_SHIFT));
        if (!page)
                return VM_FAULT_SIGBUS;

        get_page(page);
        vmf->page = page;

        return 0;
}

static struct vm_operations_struct qib_file_vm_ops = {
        .fault = qib_file_vma_fault,
};

static int mmap_kvaddr(struct vm_area_struct *vma, u64 pgaddr,
                       struct qib_ctxtdata *rcd, unsigned subctxt)
{
        struct qib_devdata *dd = rcd->dd;
        unsigned subctxt_cnt;
        unsigned long len;
        void *addr;
        size_t size;
        int ret = 0;

        subctxt_cnt = rcd->subctxt_cnt;
        size = rcd->rcvegrbuf_chunks * rcd->rcvegrbuf_size;

        /*
         * Each process has all the subctxt uregbase, rcvhdrq, and
         * rcvegrbufs mmapped - as an array for all the processes,
         * and also separately for this process.
         */
        if (pgaddr == cvt_kvaddr(rcd->subctxt_uregbase)) {
                addr = rcd->subctxt_uregbase;
                size = PAGE_SIZE * subctxt_cnt;
        } else if (pgaddr == cvt_kvaddr(rcd->subctxt_rcvhdr_base)) {
                addr = rcd->subctxt_rcvhdr_base;
                size = rcd->rcvhdrq_size * subctxt_cnt;
        } else if (pgaddr == cvt_kvaddr(rcd->subctxt_rcvegrbuf)) {
                addr = rcd->subctxt_rcvegrbuf;
                size *= subctxt_cnt;
        } else if (pgaddr == cvt_kvaddr(rcd->subctxt_uregbase +
                                        PAGE_SIZE * subctxt)) {
                addr = rcd->subctxt_uregbase + PAGE_SIZE * subctxt;
                size = PAGE_SIZE;
        } else if (pgaddr == cvt_kvaddr(rcd->subctxt_rcvhdr_base +
                                        rcd->rcvhdrq_size * subctxt)) {
                addr = rcd->subctxt_rcvhdr_base +
                        rcd->rcvhdrq_size * subctxt;
                size = rcd->rcvhdrq_size;
        } else if (pgaddr == cvt_kvaddr(&rcd->user_event_mask[subctxt])) {
                addr = rcd->user_event_mask;
                size = PAGE_SIZE;
        } else if (pgaddr == cvt_kvaddr(rcd->subctxt_rcvegrbuf +
                                        size * subctxt)) {
                addr = rcd->subctxt_rcvegrbuf + size * subctxt;
                /* rcvegrbufs are read-only on the slave */
                if (vma->vm_flags & VM_WRITE) {
                        qib_devinfo(dd->pcidev,
                                 "Can't map eager buffers as "
                                 "writable (flags=%lx)\n", vma->vm_flags);
                        ret = -EPERM;
                        goto bail;
                }
                /*
                 * Don't allow permission to later change to writeable
                 * with mprotect.
                 */
                vma->vm_flags &= ~VM_MAYWRITE;
        } else
                goto bail;
        len = vma->vm_end - vma->vm_start;
        if (len > size) {
                ret = -EINVAL;
                goto bail;
        }

        vma->vm_pgoff = (unsigned long) addr >> PAGE_SHIFT;
        vma->vm_ops = &qib_file_vm_ops;
        vma->vm_flags |= VM_RESERVED | VM_DONTEXPAND;
        ret = 1;

bail:
        return ret;
}

/**
 * qib_mmapf - mmap various structures into user space
 * @fp: the file pointer
 * @vma: the VM area
 *
 * We use this to have a shared buffer between the kernel and the user code
 * for the rcvhdr queue, egr buffers, and the per-context user regs and pio
 * buffers in the chip.  We have the open and close entries so we can bump
 * the ref count and keep the driver from being unloaded while still mapped.
 */
static int qib_mmapf(struct file *fp, struct vm_area_struct *vma)
{
        struct qib_ctxtdata *rcd;
        struct qib_devdata *dd;
        u64 pgaddr, ureg;
        unsigned piobufs, piocnt;
        int ret, match = 1;

        rcd = ctxt_fp(fp);
        if (!rcd || !(vma->vm_flags & VM_SHARED)) {
                ret = -EINVAL;
                goto bail;
        }
        dd = rcd->dd;

        /*
         * This is the qib_do_user_init() code, mapping the shared buffers
         * and per-context user registers into the user process. The address
         * referred to by vm_pgoff is the file offset passed via mmap().
         * For shared contexts, this is the kernel vmalloc() address of the
         * pages to share with the master.
         * For non-shared or master ctxts, this is a physical address.
         * We only do one mmap for each space mapped.
         */
        pgaddr = vma->vm_pgoff << PAGE_SHIFT;

        /*
         * Check for 0 in case one of the allocations failed, but user
         * called mmap anyway.
         */
        if (!pgaddr)  {
                ret = -EINVAL;
                goto bail;
        }

        /*
         * Physical addresses must fit in 40 bits for our hardware.
         * Check for kernel virtual addresses first, anything else must
         * match a HW or memory address.
         */
        ret = mmap_kvaddr(vma, pgaddr, rcd, subctxt_fp(fp));
        if (ret) {
                if (ret > 0)
                        ret = 0;
                goto bail;
        }

        ureg = dd->uregbase + dd->ureg_align * rcd->ctxt;
        if (!rcd->subctxt_cnt) {
                /* ctxt is not shared */
                piocnt = rcd->piocnt;
                piobufs = rcd->piobufs;
        } else if (!subctxt_fp(fp)) {
                /* caller is the master */
                piocnt = (rcd->piocnt / rcd->subctxt_cnt) +
                         (rcd->piocnt % rcd->subctxt_cnt);
                piobufs = rcd->piobufs +
                        dd->palign * (rcd->piocnt - piocnt);
        } else {
                unsigned slave = subctxt_fp(fp) - 1;

                /* caller is a slave */
                piocnt = rcd->piocnt / rcd->subctxt_cnt;
                piobufs = rcd->piobufs + dd->palign * piocnt * slave;
        }

        if (pgaddr == ureg)
                ret = mmap_ureg(vma, dd, ureg);
        else if (pgaddr == piobufs)
                ret = mmap_piobufs(vma, dd, rcd, piobufs, piocnt);
        else if (pgaddr == dd->pioavailregs_phys)
                /* in-memory copy of pioavail registers */
                ret = qib_mmap_mem(vma, rcd, PAGE_SIZE,
                                   (void *) dd->pioavailregs_dma, 0,
                                   "pioavail registers");
        else if (pgaddr == rcd->rcvegr_phys)
                ret = mmap_rcvegrbufs(vma, rcd);
        else if (pgaddr == (u64) rcd->rcvhdrq_phys)
                /*
                 * The rcvhdrq itself; multiple pages, contiguous
                 * from an i/o perspective.  Shared contexts need
                 * to map r/w, so we allow writing.
                 */
                ret = qib_mmap_mem(vma, rcd, rcd->rcvhdrq_size,
                                   rcd->rcvhdrq, 1, "rcvhdrq");
        else if (pgaddr == (u64) rcd->rcvhdrqtailaddr_phys)
                /* in-memory copy of rcvhdrq tail register */
                ret = qib_mmap_mem(vma, rcd, PAGE_SIZE,
                                   rcd->rcvhdrtail_kvaddr, 0,
                                   "rcvhdrq tail");
        else
                match = 0;
        if (!match)
                ret = -EINVAL;

        vma->vm_private_data = NULL;

        if (ret < 0)
                qib_devinfo(dd->pcidev,
                         "mmap Failure %d: off %llx len %lx\n",
                         -ret, (unsigned long long)pgaddr,
                         vma->vm_end - vma->vm_start);
bail:
        return ret;
}

static unsigned int qib_poll_urgent(struct qib_ctxtdata *rcd,
                                    struct file *fp,
                                    struct poll_table_struct *pt)
{
        struct qib_devdata *dd = rcd->dd;
        unsigned pollflag;

        poll_wait(fp, &rcd->wait, pt);

        spin_lock_irq(&dd->uctxt_lock);
        if (rcd->urgent != rcd->urgent_poll) {
                pollflag = POLLIN | POLLRDNORM;
                rcd->urgent_poll = rcd->urgent;
        } else {
                pollflag = 0;
                set_bit(QIB_CTXT_WAITING_URG, &rcd->flag);
        }
        spin_unlock_irq(&dd->uctxt_lock);

        return pollflag;
}

static unsigned int qib_poll_next(struct qib_ctxtdata *rcd,
                                  struct file *fp,
                                  struct poll_table_struct *pt)
{
        struct qib_devdata *dd = rcd->dd;
        unsigned pollflag;

        poll_wait(fp, &rcd->wait, pt);

        spin_lock_irq(&dd->uctxt_lock);
        if (dd->f_hdrqempty(rcd)) {
                set_bit(QIB_CTXT_WAITING_RCV, &rcd->flag);
                dd->f_rcvctrl(rcd->ppd, QIB_RCVCTRL_INTRAVAIL_ENB, rcd->ctxt);
                pollflag = 0;
        } else
                pollflag = POLLIN | POLLRDNORM;
        spin_unlock_irq(&dd->uctxt_lock);

        return pollflag;
}

static unsigned int qib_poll(struct file *fp, struct poll_table_struct *pt)
{
        struct qib_ctxtdata *rcd;
        unsigned pollflag;

        rcd = ctxt_fp(fp);
        if (!rcd)
                pollflag = POLLERR;
        else if (rcd->poll_type == QIB_POLL_TYPE_URGENT)
                pollflag = qib_poll_urgent(rcd, fp, pt);
        else  if (rcd->poll_type == QIB_POLL_TYPE_ANYRCV)
                pollflag = qib_poll_next(rcd, fp, pt);
        else /* invalid */
                pollflag = POLLERR;

        return pollflag;
}

/*
 * Check that userland and driver are compatible for subcontexts.
 */
static int qib_compatible_subctxts(int user_swmajor, int user_swminor)
{
        /* this code is written long-hand for clarity */
        if (QIB_USER_SWMAJOR != user_swmajor) {
                /* no promise of compatibility if major mismatch */
                return 0;
        }
        if (QIB_USER_SWMAJOR == 1) {
                switch (QIB_USER_SWMINOR) {
                case 0:
                case 1:
                case 2:
                        /* no subctxt implementation so cannot be compatible */
                        return 0;
                case 3:
                        /* 3 is only compatible with itself */
                        return user_swminor == 3;
                default:
                        /* >= 4 are compatible (or are expected to be) */
                        return user_swminor >= 4;
                }
        }
        /* make no promises yet for future major versions */
        return 0;
}

static int init_subctxts(struct qib_devdata *dd,
                         struct qib_ctxtdata *rcd,
                         const struct qib_user_info *uinfo)
{
        int ret = 0;
        unsigned num_subctxts;
        size_t size;

        /*
         * If the user is requesting zero subctxts,
         * skip the subctxt allocation.
         */
        if (uinfo->spu_subctxt_cnt <= 0)
                goto bail;
        num_subctxts = uinfo->spu_subctxt_cnt;

        /* Check for subctxt compatibility */
        if (!qib_compatible_subctxts(uinfo->spu_userversion >> 16,
                uinfo->spu_userversion & 0xffff)) {
                qib_devinfo(dd->pcidev,
                         "Mismatched user version (%d.%d) and driver "
                         "version (%d.%d) while context sharing. Ensure "
                         "that driver and library are from the same "
                         "release.\n",
                         (int) (uinfo->spu_userversion >> 16),
                         (int) (uinfo->spu_userversion & 0xffff),
                         QIB_USER_SWMAJOR, QIB_USER_SWMINOR);
                goto bail;
        }
        if (num_subctxts > QLOGIC_IB_MAX_SUBCTXT) {
                ret = -EINVAL;
                goto bail;
        }

        rcd->subctxt_uregbase = vmalloc_user(PAGE_SIZE * num_subctxts);
        if (!rcd->subctxt_uregbase) {
                ret = -ENOMEM;
                goto bail;
        }
        /* Note: rcd->rcvhdrq_size isn't initialized yet. */
        size = ALIGN(dd->rcvhdrcnt * dd->rcvhdrentsize *
                     sizeof(u32), PAGE_SIZE) * num_subctxts;
        rcd->subctxt_rcvhdr_base = vmalloc_user(size);
        if (!rcd->subctxt_rcvhdr_base) {
                ret = -ENOMEM;
                goto bail_ureg;
        }

        rcd->subctxt_rcvegrbuf = vmalloc_user(rcd->rcvegrbuf_chunks *
                                              rcd->rcvegrbuf_size *
                                              num_subctxts);
        if (!rcd->subctxt_rcvegrbuf) {
                ret = -ENOMEM;
                goto bail_rhdr;
        }

        rcd->subctxt_cnt = uinfo->spu_subctxt_cnt;
        rcd->subctxt_id = uinfo->spu_subctxt_id;
        rcd->active_slaves = 1;
        rcd->redirect_seq_cnt = 1;
        set_bit(QIB_CTXT_MASTER_UNINIT, &rcd->flag);
        goto bail;

bail_rhdr:
        vfree(rcd->subctxt_rcvhdr_base);
bail_ureg:
        vfree(rcd->subctxt_uregbase);
        rcd->subctxt_uregbase = NULL;
bail:
        return ret;
}

static int setup_ctxt(struct qib_pportdata *ppd, int ctxt,
                      struct file *fp, const struct qib_user_info *uinfo)
{
        struct qib_devdata *dd = ppd->dd;
        struct qib_ctxtdata *rcd;
        void *ptmp = NULL;
        int ret;

        rcd = qib_create_ctxtdata(ppd, ctxt);

        /*
         * Allocate memory for use in qib_tid_update() at open to
         * reduce cost of expected send setup per message segment
         */
        if (rcd)
                ptmp = kmalloc(dd->rcvtidcnt * sizeof(u16) +
                               dd->rcvtidcnt * sizeof(struct page **),
                               GFP_KERNEL);

        if (!rcd || !ptmp) {
                qib_dev_err(dd, "Unable to allocate ctxtdata "
                            "memory, failing open\n");
                ret = -ENOMEM;
                goto bailerr;
        }
        rcd->userversion = uinfo->spu_userversion;
        ret = init_subctxts(dd, rcd, uinfo);
        if (ret)
                goto bailerr;
        rcd->tid_pg_list = ptmp;
        rcd->pid = current->pid;
        init_waitqueue_head(&dd->rcd[ctxt]->wait);
        strlcpy(rcd->comm, current->comm, sizeof(rcd->comm));
        ctxt_fp(fp) = rcd;
        qib_stats.sps_ctxts++;
        ret = 0;
        goto bail;

bailerr:
        dd->rcd[ctxt] = NULL;
        kfree(rcd);
        kfree(ptmp);
bail:
        return ret;
}

static inline int usable(struct qib_pportdata *ppd)
{
        struct qib_devdata *dd = ppd->dd;

        return dd && (dd->flags & QIB_PRESENT) && dd->kregbase && ppd->lid &&
                (ppd->lflags & QIBL_LINKACTIVE);
}

/*
 * Select a context on the given device, either using a requested port
 * or the port based on the context number.
 */
static int choose_port_ctxt(struct file *fp, struct qib_devdata *dd, u32 port,
                            const struct qib_user_info *uinfo)
{
        struct qib_pportdata *ppd = NULL;
        int ret, ctxt;

        if (port) {
                if (!usable(dd->pport + port - 1)) {
                        ret = -ENETDOWN;
                        goto done;
                } else
                        ppd = dd->pport + port - 1;
        }
        for (ctxt = dd->first_user_ctxt; ctxt < dd->cfgctxts && dd->rcd[ctxt];
             ctxt++)
                ;
        if (ctxt == dd->cfgctxts) {
                ret = -EBUSY;
                goto done;
        }
        if (!ppd) {
                u32 pidx = ctxt % dd->num_pports;
                if (usable(dd->pport + pidx))
                        ppd = dd->pport + pidx;
                else {
                        for (pidx = 0; pidx < dd->num_pports && !ppd;
                             pidx++)
                                if (usable(dd->pport + pidx))
                                        ppd = dd->pport + pidx;
                }
        }
        ret = ppd ? setup_ctxt(ppd, ctxt, fp, uinfo) : -ENETDOWN;
done:
        return ret;
}

static int find_free_ctxt(int unit, struct file *fp,
                          const struct qib_user_info *uinfo)
{
        struct qib_devdata *dd = qib_lookup(unit);
        int ret;

        if (!dd || (uinfo->spu_port && uinfo->spu_port > dd->num_pports))
                ret = -ENODEV;
        else
                ret = choose_port_ctxt(fp, dd, uinfo->spu_port, uinfo);

        return ret;
}

static int get_a_ctxt(struct file *fp, const struct qib_user_info *uinfo,
                      unsigned alg)
{
        struct qib_devdata *udd = NULL;
        int ret = 0, devmax, npresent, nup, ndev, dusable = 0, i;
        u32 port = uinfo->spu_port, ctxt;

        devmax = qib_count_units(&npresent, &nup);
        if (!npresent) {
                ret = -ENXIO;
                goto done;
        }
        if (nup == 0) {
                ret = -ENETDOWN;
                goto done;
        }

        if (alg == QIB_PORT_ALG_ACROSS) {
                unsigned inuse = ~0U;
                /* find device (with ACTIVE ports) with fewest ctxts in use */
                for (ndev = 0; ndev < devmax; ndev++) {
                        struct qib_devdata *dd = qib_lookup(ndev);
                        unsigned cused = 0, cfree = 0, pusable = 0;
                        if (!dd)
                                continue;
                        if (port && port <= dd->num_pports &&
                            usable(dd->pport + port - 1))
                                pusable = 1;
                        else
                                for (i = 0; i < dd->num_pports; i++)
                                        if (usable(dd->pport + i))
                                                pusable++;
                        if (!pusable)
                                continue;
                        for (ctxt = dd->first_user_ctxt; ctxt < dd->cfgctxts;
                             ctxt++)
                                if (dd->rcd[ctxt])
                                        cused++;
                                else
                                        cfree++;
                        if (pusable && cfree && cused < inuse) {
                                udd = dd;
                                inuse = cused;
                        }
                }
                if (udd) {
                        ret = choose_port_ctxt(fp, udd, port, uinfo);
                        goto done;
                }
        } else {
                for (ndev = 0; ndev < devmax; ndev++) {
                        struct qib_devdata *dd = qib_lookup(ndev);
                        if (dd) {
                                ret = choose_port_ctxt(fp, dd, port, uinfo);
                                if (!ret)
                                        goto done;
                                if (ret == -EBUSY)
                                        dusable++;
                        }
                }
        }
        ret = dusable ? -EBUSY : -ENETDOWN;

done:
        return ret;
}

static int find_shared_ctxt(struct file *fp,
                            const struct qib_user_info *uinfo)
{
        int devmax, ndev, i;
        int ret = 0;

        devmax = qib_count_units(NULL, NULL);

        for (ndev = 0; ndev < devmax; ndev++) {
                struct qib_devdata *dd = qib_lookup(ndev);

                /* device portion of usable() */
                if (!(dd && (dd->flags & QIB_PRESENT) && dd->kregbase))
                        continue;
                for (i = dd->first_user_ctxt; i < dd->cfgctxts; i++) {
                        struct qib_ctxtdata *rcd = dd->rcd[i];

                        /* Skip ctxts which are not yet open */
                        if (!rcd || !rcd->cnt)
                                continue;
                        /* Skip ctxt if it doesn't match the requested one */
                        if (rcd->subctxt_id != uinfo->spu_subctxt_id)
                                continue;
                        /* Verify the sharing process matches the master */
                        if (rcd->subctxt_cnt != uinfo->spu_subctxt_cnt ||
                            rcd->userversion != uinfo->spu_userversion ||
                            rcd->cnt >= rcd->subctxt_cnt) {
                                ret = -EINVAL;
                                goto done;
                        }
                        ctxt_fp(fp) = rcd;
                        subctxt_fp(fp) = rcd->cnt++;
                        rcd->subpid[subctxt_fp(fp)] = current->pid;
                        tidcursor_fp(fp) = 0;
                        rcd->active_slaves |= 1 << subctxt_fp(fp);
                        ret = 1;
                        goto done;
                }
        }

done:
        return ret;
}

static int qib_open(struct inode *in, struct file *fp)
{
        /* The real work is performed later in qib_assign_ctxt() */
        fp->private_data = kzalloc(sizeof(struct qib_filedata), GFP_KERNEL);
        if (fp->private_data) /* no cpu affinity by default */
                ((struct qib_filedata *)fp->private_data)->rec_cpu_num = -1;
        return fp->private_data ? 0 : -ENOMEM;
}

/*
 * Get ctxt early, so can set affinity prior to memory allocation.
 */
static int qib_assign_ctxt(struct file *fp, const struct qib_user_info *uinfo)
{
        int ret;
        int i_minor;
        unsigned swmajor, swminor, alg = QIB_PORT_ALG_ACROSS;

        /* Check to be sure we haven't already initialized this file */
        if (ctxt_fp(fp)) {
                ret = -EINVAL;
                goto done;
        }

        /* for now, if major version is different, bail */
        swmajor = uinfo->spu_userversion >> 16;
        if (swmajor != QIB_USER_SWMAJOR) {
                ret = -ENODEV;
                goto done;
        }

        swminor = uinfo->spu_userversion & 0xffff;

        if (swminor >= 11 && uinfo->spu_port_alg < QIB_PORT_ALG_COUNT)
                alg = uinfo->spu_port_alg;

        mutex_lock(&qib_mutex);

        if (qib_compatible_subctxts(swmajor, swminor) &&
            uinfo->spu_subctxt_cnt) {
                ret = find_shared_ctxt(fp, uinfo);
                if (ret) {
                        if (ret > 0)
                                ret = 0;
                        goto done_chk_sdma;
                }
        }

        i_minor = iminor(fp->f_dentry->d_inode) - QIB_USER_MINOR_BASE;
        if (i_minor)
                ret = find_free_ctxt(i_minor - 1, fp, uinfo);
        else
                ret = get_a_ctxt(fp, uinfo, alg);

done_chk_sdma:
        if (!ret) {
                struct qib_filedata *fd = fp->private_data;
                const struct qib_ctxtdata *rcd = fd->rcd;
                const struct qib_devdata *dd = rcd->dd;
                unsigned int weight;

                if (dd->flags & QIB_HAS_SEND_DMA) {
                        fd->pq = qib_user_sdma_queue_create(&dd->pcidev->dev,
                                                            dd->unit,
                                                            rcd->ctxt,
                                                            fd->subctxt);
                        if (!fd->pq)
                                ret = -ENOMEM;
                }

                /*
                 * If process has NOT already set it's affinity, select and
                 * reserve a processor for it, as a rendezvous for all
                 * users of the driver.  If they don't actually later
                 * set affinity to this cpu, or set it to some other cpu,
                 * it just means that sooner or later we don't recommend
                 * a cpu, and let the scheduler do it's best.
                 */
                weight = cpumask_weight(tsk_cpus_allowed(current));
                if (!ret && weight >= qib_cpulist_count) {
                        int cpu;
                        cpu = find_first_zero_bit(qib_cpulist,
                                                  qib_cpulist_count);
                        if (cpu != qib_cpulist_count) {
                                __set_bit(cpu, qib_cpulist);
                                fd->rec_cpu_num = cpu;
                        }
                } else if (weight == 1 &&
                        test_bit(cpumask_first(tsk_cpus_allowed(current)),
                                 qib_cpulist))
                        qib_devinfo(dd->pcidev, "%s PID %u affinity "
                                    "set to cpu %d; already allocated\n",
                                    current->comm, current->pid,
                                    cpumask_first(tsk_cpus_allowed(current)));
        }

        mutex_unlock(&qib_mutex);

done:
        return ret;
}


static int qib_do_user_init(struct file *fp,
                            const struct qib_user_info *uinfo)
{
        int ret;
        struct qib_ctxtdata *rcd = ctxt_fp(fp);
        struct qib_devdata *dd;
        unsigned uctxt;

        /* Subctxts don't need to initialize anything since master did it. */
        if (subctxt_fp(fp)) {
                ret = wait_event_interruptible(rcd->wait,
                        !test_bit(QIB_CTXT_MASTER_UNINIT, &rcd->flag));
                goto bail;
        }

        dd = rcd->dd;

        /* some ctxts may get extra buffers, calculate that here */
        uctxt = rcd->ctxt - dd->first_user_ctxt;
        if (uctxt < dd->ctxts_extrabuf) {
                rcd->piocnt = dd->pbufsctxt + 1;
                rcd->pio_base = rcd->piocnt * uctxt;
        } else {
                rcd->piocnt = dd->pbufsctxt;
                rcd->pio_base = rcd->piocnt * uctxt +
                        dd->ctxts_extrabuf;
        }

        /*
         * All user buffers are 2KB buffers.  If we ever support
         * giving 4KB buffers to user processes, this will need some
         * work.  Can't use piobufbase directly, because it has
         * both 2K and 4K buffer base values.  So check and handle.
         */
        if ((rcd->pio_base + rcd->piocnt) > dd->piobcnt2k) {
                if (rcd->pio_base >= dd->piobcnt2k) {
                        qib_dev_err(dd,
                                    "%u:ctxt%u: no 2KB buffers available\n",
                                    dd->unit, rcd->ctxt);
                        ret = -ENOBUFS;
                        goto bail;
                }
                rcd->piocnt = dd->piobcnt2k - rcd->pio_base;
                qib_dev_err(dd, "Ctxt%u: would use 4KB bufs, using %u\n",
                            rcd->ctxt, rcd->piocnt);
        }

        rcd->piobufs = dd->pio2k_bufbase + rcd->pio_base * dd->palign;
        qib_chg_pioavailkernel(dd, rcd->pio_base, rcd->piocnt,
                               TXCHK_CHG_TYPE_USER, rcd);
        /*
         * try to ensure that processes start up with consistent avail update
         * for their own range, at least.   If system very quiet, it might
         * have the in-memory copy out of date at startup for this range of
         * buffers, when a context gets re-used.  Do after the chg_pioavail
         * and before the rest of setup, so it's "almost certain" the dma
         * will have occurred (can't 100% guarantee, but should be many
         * decimals of 9s, with this ordering), given how much else happens
         * after this.
         */
        dd->f_sendctrl(dd->pport, QIB_SENDCTRL_AVAIL_BLIP);

        /*
         * Now allocate the rcvhdr Q and eager TIDs; skip the TID
         * array for time being.  If rcd->ctxt > chip-supported,
         * we need to do extra stuff here to handle by handling overflow
         * through ctxt 0, someday
         */
        ret = qib_create_rcvhdrq(dd, rcd);
        if (!ret)
                ret = qib_setup_eagerbufs(rcd);
        if (ret)
                goto bail_pio;

        rcd->tidcursor = 0; /* start at beginning after open */

        /* initialize poll variables... */
        rcd->urgent = 0;
        rcd->urgent_poll = 0;

        /*
         * Now enable the ctxt for receive.
         * For chips that are set to DMA the tail register to memory
         * when they change (and when the update bit transitions from
         * 0 to 1.  So for those chips, we turn it off and then back on.
         * This will (very briefly) affect any other open ctxts, but the
         * duration is very short, and therefore isn't an issue.  We
         * explicitly set the in-memory tail copy to 0 beforehand, so we
         * don't have to wait to be sure the DMA update has happened
         * (chip resets head/tail to 0 on transition to enable).
         */
        if (rcd->rcvhdrtail_kvaddr)
                qib_clear_rcvhdrtail(rcd);

        dd->f_rcvctrl(rcd->ppd, QIB_RCVCTRL_CTXT_ENB | QIB_RCVCTRL_TIDFLOW_ENB,
                      rcd->ctxt);

        /* Notify any waiting slaves */
        if (rcd->subctxt_cnt) {
                clear_bit(QIB_CTXT_MASTER_UNINIT, &rcd->flag);
                wake_up(&rcd->wait);
        }
        return 0;

bail_pio:
        qib_chg_pioavailkernel(dd, rcd->pio_base, rcd->piocnt,
                               TXCHK_CHG_TYPE_KERN, rcd);
bail:
        return ret;
}

/**
 * unlock_exptid - unlock any expected TID entries context still had in use
 * @rcd: ctxt
 *
 * We don't actually update the chip here, because we do a bulk update
 * below, using f_clear_tids.
 */
static void unlock_expected_tids(struct qib_ctxtdata *rcd)
{
        struct qib_devdata *dd = rcd->dd;
        int ctxt_tidbase = rcd->ctxt * dd->rcvtidcnt;
        int i, cnt = 0, maxtid = ctxt_tidbase + dd->rcvtidcnt;

        for (i = ctxt_tidbase; i < maxtid; i++) {
                struct page *p = dd->pageshadow[i];
                dma_addr_t phys;

                if (!p)
                        continue;

                phys = dd->physshadow[i];
                dd->physshadow[i] = dd->tidinvalid;
                dd->pageshadow[i] = NULL;
                pci_unmap_page(dd->pcidev, phys, PAGE_SIZE,
                               PCI_DMA_FROMDEVICE);
                qib_release_user_pages(&p, 1);
                cnt++;
        }
}

static int qib_close(struct inode *in, struct file *fp)
{
        int ret = 0;
        struct qib_filedata *fd;
        struct qib_ctxtdata *rcd;
        struct qib_devdata *dd;
        unsigned long flags;
        unsigned ctxt;
        pid_t pid;

        mutex_lock(&qib_mutex);

        fd = fp->private_data;
        fp->private_data = NULL;
        rcd = fd->rcd;
        if (!rcd) {
                mutex_unlock(&qib_mutex);
                goto bail;
        }

        dd = rcd->dd;

        /* ensure all pio buffer writes in progress are flushed */
        qib_flush_wc();

        /* drain user sdma queue */
        if (fd->pq) {
                qib_user_sdma_queue_drain(rcd->ppd, fd->pq);
                qib_user_sdma_queue_destroy(fd->pq);
        }

        if (fd->rec_cpu_num != -1)
                __clear_bit(fd->rec_cpu_num, qib_cpulist);

        if (--rcd->cnt) {
                /*
                 * XXX If the master closes the context before the slave(s),
                 * revoke the mmap for the eager receive queue so
                 * the slave(s) don't wait for receive data forever.
                 */
                rcd->active_slaves &= ~(1 << fd->subctxt);
                rcd->subpid[fd->subctxt] = 0;
                mutex_unlock(&qib_mutex);
                goto bail;
        }

        /* early; no interrupt users after this */
        spin_lock_irqsave(&dd->uctxt_lock, flags);
        ctxt = rcd->ctxt;
        dd->rcd[ctxt] = NULL;
        pid = rcd->pid;
        rcd->pid = 0;
        spin_unlock_irqrestore(&dd->uctxt_lock, flags);

        if (rcd->rcvwait_to || rcd->piowait_to ||
            rcd->rcvnowait || rcd->pionowait) {
                rcd->rcvwait_to = 0;
                rcd->piowait_to = 0;
                rcd->rcvnowait = 0;
                rcd->pionowait = 0;
        }
        if (rcd->flag)
                rcd->flag = 0;

        if (dd->kregbase) {
                /* atomically clear receive enable ctxt and intr avail. */
                dd->f_rcvctrl(rcd->ppd, QIB_RCVCTRL_CTXT_DIS |
                                  QIB_RCVCTRL_INTRAVAIL_DIS, ctxt);

                /* clean up the pkeys for this ctxt user */
                qib_clean_part_key(rcd, dd);
                qib_disarm_piobufs(dd, rcd->pio_base, rcd->piocnt);
                qib_chg_pioavailkernel(dd, rcd->pio_base,
                                       rcd->piocnt, TXCHK_CHG_TYPE_KERN, NULL);

                dd->f_clear_tids(dd, rcd);

                if (dd->pageshadow)
                        unlock_expected_tids(rcd);
                qib_stats.sps_ctxts--;
        }

        mutex_unlock(&qib_mutex);
        qib_free_ctxtdata(dd, rcd); /* after releasing the mutex */

bail:
        kfree(fd);
        return ret;
}

static int qib_ctxt_info(struct file *fp, struct qib_ctxt_info __user *uinfo)
{
        struct qib_ctxt_info info;
        int ret;
        size_t sz;
        struct qib_ctxtdata *rcd = ctxt_fp(fp);
        struct qib_filedata *fd;

        fd = fp->private_data;

        info.num_active = qib_count_active_units();
        info.unit = rcd->dd->unit;
        info.port = rcd->ppd->port;
        info.ctxt = rcd->ctxt;
        info.subctxt =  subctxt_fp(fp);
        /* Number of user ctxts available for this device. */
        info.num_ctxts = rcd->dd->cfgctxts - rcd->dd->first_user_ctxt;
        info.num_subctxts = rcd->subctxt_cnt;
        info.rec_cpu = fd->rec_cpu_num;
        sz = sizeof(info);

        if (copy_to_user(uinfo, &info, sz)) {
                ret = -EFAULT;
                goto bail;
        }
        ret = 0;

bail:
        return ret;
}

static int qib_sdma_get_inflight(struct qib_user_sdma_queue *pq,
                                 u32 __user *inflightp)
{
        const u32 val = qib_user_sdma_inflight_counter(pq);

        if (put_user(val, inflightp))
                return -EFAULT;

        return 0;
}

static int qib_sdma_get_complete(struct qib_pportdata *ppd,
                                 struct qib_user_sdma_queue *pq,
                                 u32 __user *completep)
{
        u32 val;
        int err;

        if (!pq)
                return -EINVAL;

        err = qib_user_sdma_make_progress(ppd, pq);
        if (err < 0)
                return err;

        val = qib_user_sdma_complete_counter(pq);
        if (put_user(val, completep))
                return -EFAULT;

        return 0;
}

static int disarm_req_delay(struct qib_ctxtdata *rcd)
{
        int ret = 0;

        if (!usable(rcd->ppd)) {
                int i;
                /*
                 * if link is down, or otherwise not usable, delay
                 * the caller up to 30 seconds, so we don't thrash
                 * in trying to get the chip back to ACTIVE, and
                 * set flag so they make the call again.
                 */
                if (rcd->user_event_mask) {
                        /*
                         * subctxt_cnt is 0 if not shared, so do base
                         * separately, first, then remaining subctxt, if any
                         */
                        set_bit(_QIB_EVENT_DISARM_BUFS_BIT,
                                &rcd->user_event_mask[0]);
                        for (i = 1; i < rcd->subctxt_cnt; i++)
                                set_bit(_QIB_EVENT_DISARM_BUFS_BIT,
                                        &rcd->user_event_mask[i]);
                }
                for (i = 0; !usable(rcd->ppd) && i < 300; i++)
                        msleep(100);
                ret = -ENETDOWN;
        }
        return ret;
}

/*
 * Find all user contexts in use, and set the specified bit in their
 * event mask.
 * See also find_ctxt() for a similar use, that is specific to send buffers.
 */
int qib_set_uevent_bits(struct qib_pportdata *ppd, const int evtbit)
{
        struct qib_ctxtdata *rcd;
        unsigned ctxt;
        int ret = 0;
        unsigned long flags;

        spin_lock_irqsave(&ppd->dd->uctxt_lock, flags);
        for (ctxt = ppd->dd->first_user_ctxt; ctxt < ppd->dd->cfgctxts;
             ctxt++) {
                rcd = ppd->dd->rcd[ctxt];
                if (!rcd)
                        continue;
                if (rcd->user_event_mask) {
                        int i;
                        /*
                         * subctxt_cnt is 0 if not shared, so do base
                         * separately, first, then remaining subctxt, if any
                         */
                        set_bit(evtbit, &rcd->user_event_mask[0]);
                        for (i = 1; i < rcd->subctxt_cnt; i++)
                                set_bit(evtbit, &rcd->user_event_mask[i]);
                }
                ret = 1;
                break;
        }
        spin_unlock_irqrestore(&ppd->dd->uctxt_lock, flags);

        return ret;
}

/*
 * clear the event notifier events for this context.
 * For the DISARM_BUFS case, we also take action (this obsoletes
 * the older QIB_CMD_DISARM_BUFS, but we keep it for backwards
 * compatibility.
 * Other bits don't currently require actions, just atomically clear.
 * User process then performs actions appropriate to bit having been
 * set, if desired, and checks again in future.
 */
static int qib_user_event_ack(struct qib_ctxtdata *rcd, int subctxt,
                              unsigned long events)
{
        int ret = 0, i;

        for (i = 0; i <= _QIB_MAX_EVENT_BIT; i++) {
                if (!test_bit(i, &events))
                        continue;
                if (i == _QIB_EVENT_DISARM_BUFS_BIT) {
                        (void)qib_disarm_piobufs_ifneeded(rcd);
                        ret = disarm_req_delay(rcd);
                } else
                        clear_bit(i, &rcd->user_event_mask[subctxt]);
        }
        return ret;
}

static ssize_t qib_write(struct file *fp, const char __user *data,
                         size_t count, loff_t *off)
{
        const struct qib_cmd __user *ucmd;
        struct qib_ctxtdata *rcd;
        const void __user *src;
        size_t consumed, copy = 0;
        struct qib_cmd cmd;
        ssize_t ret = 0;
        void *dest;

        if (count < sizeof(cmd.type)) {
                ret = -EINVAL;
                goto bail;
        }

        ucmd = (const struct qib_cmd __user *) data;

        if (copy_from_user(&cmd.type, &ucmd->type, sizeof(cmd.type))) {
                ret = -EFAULT;
                goto bail;
        }

        consumed = sizeof(cmd.type);

        switch (cmd.type) {
        case QIB_CMD_ASSIGN_CTXT:
        case QIB_CMD_USER_INIT:
                copy = sizeof(cmd.cmd.user_info);
                dest = &cmd.cmd.user_info;
                src = &ucmd->cmd.user_info;
                break;

        case QIB_CMD_RECV_CTRL:
                copy = sizeof(cmd.cmd.recv_ctrl);
                dest = &cmd.cmd.recv_ctrl;
                src = &ucmd->cmd.recv_ctrl;
                break;

        case QIB_CMD_CTXT_INFO:
                copy = sizeof(cmd.cmd.ctxt_info);
                dest = &cmd.cmd.ctxt_info;
                src = &ucmd->cmd.ctxt_info;
                break;

        case QIB_CMD_TID_UPDATE:
        case QIB_CMD_TID_FREE:
                copy = sizeof(cmd.cmd.tid_info);
                dest = &cmd.cmd.tid_info;
                src = &ucmd->cmd.tid_info;
                break;

        case QIB_CMD_SET_PART_KEY:
                copy = sizeof(cmd.cmd.part_key);
                dest = &cmd.cmd.part_key;
                src = &ucmd->cmd.part_key;
                break;

        case QIB_CMD_DISARM_BUFS:
        case QIB_CMD_PIOAVAILUPD: /* force an update of PIOAvail reg */
                copy = 0;
                src = NULL;
                dest = NULL;
                break;

        case QIB_CMD_POLL_TYPE:
                copy = sizeof(cmd.cmd.poll_type);
                dest = &cmd.cmd.poll_type;
                src = &ucmd->cmd.poll_type;
                break;

        case QIB_CMD_ARMLAUNCH_CTRL:
                copy = sizeof(cmd.cmd.armlaunch_ctrl);
                dest = &cmd.cmd.armlaunch_ctrl;
                src = &ucmd->cmd.armlaunch_ctrl;
                break;

        case QIB_CMD_SDMA_INFLIGHT:
                copy = sizeof(cmd.cmd.sdma_inflight);
                dest = &cmd.cmd.sdma_inflight;
                src = &ucmd->cmd.sdma_inflight;
                break;

        case QIB_CMD_SDMA_COMPLETE:
                copy = sizeof(cmd.cmd.sdma_complete);
                dest = &cmd.cmd.sdma_complete;
                src = &ucmd->cmd.sdma_complete;
                break;

        case QIB_CMD_ACK_EVENT:
                copy = sizeof(cmd.cmd.event_mask);
                dest = &cmd.cmd.event_mask;
                src = &ucmd->cmd.event_mask;
                break;

        default:
                ret = -EINVAL;
                goto bail;
        }

        if (copy) {
                if ((count - consumed) < copy) {
                        ret = -EINVAL;
                        goto bail;
                }
                if (copy_from_user(dest, src, copy)) {
                        ret = -EFAULT;
                        goto bail;
                }
                consumed += copy;
        }

        rcd = ctxt_fp(fp);
        if (!rcd && cmd.type != QIB_CMD_ASSIGN_CTXT) {
                ret = -EINVAL;
                goto bail;
        }

        switch (cmd.type) {
        case QIB_CMD_ASSIGN_CTXT:
                ret = qib_assign_ctxt(fp, &cmd.cmd.user_info);
                if (ret)
                        goto bail;
                break;

        case QIB_CMD_USER_INIT:
                ret = qib_do_user_init(fp, &cmd.cmd.user_info);
                if (ret)
                        goto bail;
                ret = qib_get_base_info(fp, (void __user *) (unsigned long)
                                        cmd.cmd.user_info.spu_base_info,
                                        cmd.cmd.user_info.spu_base_info_size);
                break;

        case QIB_CMD_RECV_CTRL:
                ret = qib_manage_rcvq(rcd, subctxt_fp(fp), cmd.cmd.recv_ctrl);
                break;

        case QIB_CMD_CTXT_INFO:
                ret = qib_ctxt_info(fp, (struct qib_ctxt_info __user *)
                                    (unsigned long) cmd.cmd.ctxt_info);
                break;

        case QIB_CMD_TID_UPDATE:
                ret = qib_tid_update(rcd, fp, &cmd.cmd.tid_info);
                break;

        case QIB_CMD_TID_FREE:
                ret = qib_tid_free(rcd, subctxt_fp(fp), &cmd.cmd.tid_info);
                break;

        case QIB_CMD_SET_PART_KEY:
                ret = qib_set_part_key(rcd, cmd.cmd.part_key);
                break;

        case QIB_CMD_DISARM_BUFS:
                (void)qib_disarm_piobufs_ifneeded(rcd);
                ret = disarm_req_delay(rcd);
                break;

        case QIB_CMD_PIOAVAILUPD:
                qib_force_pio_avail_update(rcd->dd);
                break;

        case QIB_CMD_POLL_TYPE:
                rcd->poll_type = cmd.cmd.poll_type;
                break;

        case QIB_CMD_ARMLAUNCH_CTRL:
                rcd->dd->f_set_armlaunch(rcd->dd, cmd.cmd.armlaunch_ctrl);
                break;

        case QIB_CMD_SDMA_INFLIGHT:
                ret = qib_sdma_get_inflight(user_sdma_queue_fp(fp),
                                            (u32 __user *) (unsigned long)
                                            cmd.cmd.sdma_inflight);
                break;

        case QIB_CMD_SDMA_COMPLETE:
                ret = qib_sdma_get_complete(rcd->ppd,
                                            user_sdma_queue_fp(fp),
                                            (u32 __user *) (unsigned long)
                                            cmd.cmd.sdma_complete);
                break;

        case QIB_CMD_ACK_EVENT:
                ret = qib_user_event_ack(rcd, subctxt_fp(fp),
                                         cmd.cmd.event_mask);
                break;
        }

        if (ret >= 0)
                ret = consumed;

bail:
        return ret;
}

static ssize_t qib_aio_write(struct kiocb *iocb, const struct iovec *iov,
                             unsigned long dim, loff_t off)
{
        struct qib_filedata *fp = iocb->ki_filp->private_data;
        struct qib_ctxtdata *rcd = ctxt_fp(iocb->ki_filp);
        struct qib_user_sdma_queue *pq = fp->pq;

        if (!dim || !pq)
                return -EINVAL;

        return qib_user_sdma_writev(rcd, pq, iov, dim);
}

static struct class *qib_class;
static dev_t qib_dev;

int qib_cdev_init(int minor, const char *name,
                  const struct file_operations *fops,
                  struct cdev **cdevp, struct device **devp)
{
        const dev_t dev = MKDEV(MAJOR(qib_dev), minor);
        struct cdev *cdev;
        struct device *device = NULL;
        int ret;

        cdev = cdev_alloc();
        if (!cdev) {
                printk(KERN_ERR QIB_DRV_NAME
                       ": Could not allocate cdev for minor %d, %s\n",
                       minor, name);
                ret = -ENOMEM;
                goto done;
        }

        cdev->owner = THIS_MODULE;
        cdev->ops = fops;
        kobject_set_name(&cdev->kobj, name);

        ret = cdev_add(cdev, dev, 1);
        if (ret < 0) {
                printk(KERN_ERR QIB_DRV_NAME
                       ": Could not add cdev for minor %d, %s (err %d)\n",
                       minor, name, -ret);
                goto err_cdev;
        }

        device = device_create(qib_class, NULL, dev, NULL, name);
        if (!IS_ERR(device))
                goto done;
        ret = PTR_ERR(device);
        device = NULL;
        printk(KERN_ERR QIB_DRV_NAME ": Could not create "
               "device for minor %d, %s (err %d)\n",
               minor, name, -ret);
err_cdev:
        cdev_del(cdev);
        cdev = NULL;
done:
        *cdevp = cdev;
        *devp = device;
        return ret;
}

void qib_cdev_cleanup(struct cdev **cdevp, struct device **devp)
{
        struct device *device = *devp;

        if (device) {
                device_unregister(device);
                *devp = NULL;
        }

        if (*cdevp) {
                cdev_del(*cdevp);
                *cdevp = NULL;
        }
}

static struct cdev *wildcard_cdev;
static struct device *wildcard_device;

int __init qib_dev_init(void)
{
        int ret;

        ret = alloc_chrdev_region(&qib_dev, 0, QIB_NMINORS, QIB_DRV_NAME);
        if (ret < 0) {
                printk(KERN_ERR QIB_DRV_NAME ": Could not allocate "
                       "chrdev region (err %d)\n", -ret);
                goto done;
        }

        qib_class = class_create(THIS_MODULE, "ipath");
        if (IS_ERR(qib_class)) {
                ret = PTR_ERR(qib_class);
                printk(KERN_ERR QIB_DRV_NAME ": Could not create "
                       "device class (err %d)\n", -ret);
                unregister_chrdev_region(qib_dev, QIB_NMINORS);
        }

done:
        return ret;
}

void qib_dev_cleanup(void)
{
        if (qib_class) {
                class_destroy(qib_class);
                qib_class = NULL;
        }

        unregister_chrdev_region(qib_dev, QIB_NMINORS);
}

static atomic_t user_count = ATOMIC_INIT(0);

static void qib_user_remove(struct qib_devdata *dd)
{
        if (atomic_dec_return(&user_count) == 0)
                qib_cdev_cleanup(&wildcard_cdev, &wildcard_device);

        qib_cdev_cleanup(&dd->user_cdev, &dd->user_device);
}

static int qib_user_add(struct qib_devdata *dd)
{
        char name[10];
        int ret;

        if (atomic_inc_return(&user_count) == 1) {
                ret = qib_cdev_init(0, "ipath", &qib_file_ops,
                                    &wildcard_cdev, &wildcard_device);
                if (ret)
                        goto done;
        }

        snprintf(name, sizeof(name), "ipath%d", dd->unit);
        ret = qib_cdev_init(dd->unit + 1, name, &qib_file_ops,
                            &dd->user_cdev, &dd->user_device);
        if (ret)
                qib_user_remove(dd);
done:
        return ret;
}

/*
 * Create per-unit files in /dev
 */
int qib_device_create(struct qib_devdata *dd)
{
        int r, ret;

        r = qib_user_add(dd);
        ret = qib_diag_add(dd);
        if (r && !ret)
                ret = r;
        return ret;
}

/*
 * Remove per-unit files in /dev
 * void, core kernel returns no errors for this stuff
 */
void qib_device_remove(struct qib_devdata *dd)
{
        qib_user_remove(dd);
        qib_diag_remove(dd);
}