locking/refcounts: Include fewer headers in <linux/refcount.h>

[linux/fpc-iii.git] / drivers / infiniband / core / rdma_core.c

/*
 * Copyright (c) 2016, Mellanox Technologies 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/file.h>
#include <linux/anon_inodes.h>
#include <rdma/ib_verbs.h>
#include <rdma/uverbs_types.h>
#include <linux/rcupdate.h>
#include <rdma/uverbs_ioctl.h>
#include <rdma/rdma_user_ioctl.h>
#include "uverbs.h"
#include "core_priv.h"
#include "rdma_core.h"

int uverbs_ns_idx(u16 *id, unsigned int ns_count)
{
        int ret = (*id & UVERBS_ID_NS_MASK) >> UVERBS_ID_NS_SHIFT;

        if (ret >= ns_count)
                return -EINVAL;

        *id &= ~UVERBS_ID_NS_MASK;
        return ret;
}

const struct uverbs_object_spec *uverbs_get_object(const struct ib_device *ibdev,
                                                   uint16_t object)
{
        const struct uverbs_root_spec *object_hash = ibdev->specs_root;
        const struct uverbs_object_spec_hash *objects;
        int ret = uverbs_ns_idx(&object, object_hash->num_buckets);

        if (ret < 0)
                return NULL;

        objects = object_hash->object_buckets[ret];

        if (object >= objects->num_objects)
                return NULL;

        return objects->objects[object];
}

const struct uverbs_method_spec *uverbs_get_method(const struct uverbs_object_spec *object,
                                                   uint16_t method)
{
        const struct uverbs_method_spec_hash *methods;
        int ret = uverbs_ns_idx(&method, object->num_buckets);

        if (ret < 0)
                return NULL;

        methods = object->method_buckets[ret];
        if (method >= methods->num_methods)
                return NULL;

        return methods->methods[method];
}

void uverbs_uobject_get(struct ib_uobject *uobject)
{
        kref_get(&uobject->ref);
}

static void uverbs_uobject_free(struct kref *ref)
{
        struct ib_uobject *uobj =
                container_of(ref, struct ib_uobject, ref);

        if (uobj->type->type_class->needs_kfree_rcu)
                kfree_rcu(uobj, rcu);
        else
                kfree(uobj);
}

void uverbs_uobject_put(struct ib_uobject *uobject)
{
        kref_put(&uobject->ref, uverbs_uobject_free);
}

static int uverbs_try_lock_object(struct ib_uobject *uobj, bool exclusive)
{
        /*
         * When a shared access is required, we use a positive counter. Each
         * shared access request checks that the value != -1 and increment it.
         * Exclusive access is required for operations like write or destroy.
         * In exclusive access mode, we check that the counter is zero (nobody
         * claimed this object) and we set it to -1. Releasing a shared access
         * lock is done simply by decreasing the counter. As for exclusive
         * access locks, since only a single one of them is is allowed
         * concurrently, setting the counter to zero is enough for releasing
         * this lock.
         */
        if (!exclusive)
                return atomic_fetch_add_unless(&uobj->usecnt, 1, -1) == -1 ?
                        -EBUSY : 0;

        /* lock is either WRITE or DESTROY - should be exclusive */
        return atomic_cmpxchg(&uobj->usecnt, 0, -1) == 0 ? 0 : -EBUSY;
}

static struct ib_uobject *alloc_uobj(struct ib_ucontext *context,
                                     const struct uverbs_obj_type *type)
{
        struct ib_uobject *uobj = kzalloc(type->obj_size, GFP_KERNEL);

        if (!uobj)
                return ERR_PTR(-ENOMEM);
        /*
         * user_handle should be filled by the handler,
         * The object is added to the list in the commit stage.
         */
        uobj->context = context;
        uobj->type = type;
        /*
         * Allocated objects start out as write locked to deny any other
         * syscalls from accessing them until they are committed. See
         * rdma_alloc_commit_uobject
         */
        atomic_set(&uobj->usecnt, -1);
        kref_init(&uobj->ref);

        return uobj;
}

static int idr_add_uobj(struct ib_uobject *uobj)
{
        int ret;

        idr_preload(GFP_KERNEL);
        spin_lock(&uobj->context->ufile->idr_lock);

        /*
         * We start with allocating an idr pointing to NULL. This represents an
         * object which isn't initialized yet. We'll replace it later on with
         * the real object once we commit.
         */
        ret = idr_alloc(&uobj->context->ufile->idr, NULL, 0,
                        min_t(unsigned long, U32_MAX - 1, INT_MAX), GFP_NOWAIT);
        if (ret >= 0)
                uobj->id = ret;

        spin_unlock(&uobj->context->ufile->idr_lock);
        idr_preload_end();

        return ret < 0 ? ret : 0;
}

/*
 * It only removes it from the uobjects list, uverbs_uobject_put() is still
 * required.
 */
static void uverbs_idr_remove_uobj(struct ib_uobject *uobj)
{
        spin_lock(&uobj->context->ufile->idr_lock);
        idr_remove(&uobj->context->ufile->idr, uobj->id);
        spin_unlock(&uobj->context->ufile->idr_lock);
}

/* Returns the ib_uobject or an error. The caller should check for IS_ERR. */
static struct ib_uobject *lookup_get_idr_uobject(const struct uverbs_obj_type *type,
                                                 struct ib_ucontext *ucontext,
                                                 int id, bool exclusive)
{
        struct ib_uobject *uobj;

        rcu_read_lock();
        /* object won't be released as we're protected in rcu */
        uobj = idr_find(&ucontext->ufile->idr, id);
        if (!uobj) {
                uobj = ERR_PTR(-ENOENT);
                goto free;
        }

        /*
         * The idr_find is guaranteed to return a pointer to something that
         * isn't freed yet, or NULL, as the free after idr_remove goes through
         * kfree_rcu(). However the object may still have been released and
         * kfree() could be called at any time.
         */
        if (!kref_get_unless_zero(&uobj->ref))
                uobj = ERR_PTR(-ENOENT);

free:
        rcu_read_unlock();
        return uobj;
}

static struct ib_uobject *lookup_get_fd_uobject(const struct uverbs_obj_type *type,
                                                struct ib_ucontext *ucontext,
                                                int id, bool exclusive)
{
        struct file *f;
        struct ib_uobject *uobject;
        const struct uverbs_obj_fd_type *fd_type =
                container_of(type, struct uverbs_obj_fd_type, type);

        if (exclusive)
                return ERR_PTR(-EOPNOTSUPP);

        f = fget(id);
        if (!f)
                return ERR_PTR(-EBADF);

        uobject = f->private_data;
        /*
         * fget(id) ensures we are not currently running uverbs_close_fd,
         * and the caller is expected to ensure that uverbs_close_fd is never
         * done while a call top lookup is possible.
         */
        if (f->f_op != fd_type->fops) {
                fput(f);
                return ERR_PTR(-EBADF);
        }

        uverbs_uobject_get(uobject);
        return uobject;
}

struct ib_uobject *rdma_lookup_get_uobject(const struct uverbs_obj_type *type,
                                           struct ib_ucontext *ucontext,
                                           int id, bool exclusive)
{
        struct ib_uobject *uobj;
        int ret;

        uobj = type->type_class->lookup_get(type, ucontext, id, exclusive);
        if (IS_ERR(uobj))
                return uobj;

        if (uobj->type != type) {
                ret = -EINVAL;
                goto free;
        }

        ret = uverbs_try_lock_object(uobj, exclusive);
        if (ret) {
                WARN(ucontext->cleanup_reason,
                     "ib_uverbs: Trying to lookup_get while cleanup context\n");
                goto free;
        }

        return uobj;
free:
        uobj->type->type_class->lookup_put(uobj, exclusive);
        uverbs_uobject_put(uobj);
        return ERR_PTR(ret);
}

static struct ib_uobject *alloc_begin_idr_uobject(const struct uverbs_obj_type *type,
                                                  struct ib_ucontext *ucontext)
{
        int ret;
        struct ib_uobject *uobj;

        uobj = alloc_uobj(ucontext, type);
        if (IS_ERR(uobj))
                return uobj;

        ret = idr_add_uobj(uobj);
        if (ret)
                goto uobj_put;

        ret = ib_rdmacg_try_charge(&uobj->cg_obj, ucontext->device,
                                   RDMACG_RESOURCE_HCA_OBJECT);
        if (ret)
                goto idr_remove;

        return uobj;

idr_remove:
        uverbs_idr_remove_uobj(uobj);
uobj_put:
        uverbs_uobject_put(uobj);
        return ERR_PTR(ret);
}

static struct ib_uobject *alloc_begin_fd_uobject(const struct uverbs_obj_type *type,
                                                 struct ib_ucontext *ucontext)
{
        const struct uverbs_obj_fd_type *fd_type =
                container_of(type, struct uverbs_obj_fd_type, type);
        int new_fd;
        struct ib_uobject *uobj;
        struct ib_uobject_file *uobj_file;
        struct file *filp;

        new_fd = get_unused_fd_flags(O_CLOEXEC);
        if (new_fd < 0)
                return ERR_PTR(new_fd);

        uobj = alloc_uobj(ucontext, type);
        if (IS_ERR(uobj)) {
                put_unused_fd(new_fd);
                return uobj;
        }

        uobj_file = container_of(uobj, struct ib_uobject_file, uobj);
        filp = anon_inode_getfile(fd_type->name,
                                  fd_type->fops,
                                  uobj_file,
                                  fd_type->flags);
        if (IS_ERR(filp)) {
                put_unused_fd(new_fd);
                uverbs_uobject_put(uobj);
                return (void *)filp;
        }

        uobj_file->uobj.id = new_fd;
        uobj_file->uobj.object = filp;
        uobj_file->ufile = ucontext->ufile;
        INIT_LIST_HEAD(&uobj->list);
        kref_get(&uobj_file->ufile->ref);

        return uobj;
}

struct ib_uobject *rdma_alloc_begin_uobject(const struct uverbs_obj_type *type,
                                            struct ib_ucontext *ucontext)
{
        return type->type_class->alloc_begin(type, ucontext);
}

static int __must_check remove_commit_idr_uobject(struct ib_uobject *uobj,
                                                  enum rdma_remove_reason why)
{
        const struct uverbs_obj_idr_type *idr_type =
                container_of(uobj->type, struct uverbs_obj_idr_type,
                             type);
        int ret = idr_type->destroy_object(uobj, why);

        /*
         * We can only fail gracefully if the user requested to destroy the
         * object. In the rest of the cases, just remove whatever you can.
         */
        if (why == RDMA_REMOVE_DESTROY && ret)
                return ret;

        ib_rdmacg_uncharge(&uobj->cg_obj, uobj->context->device,
                           RDMACG_RESOURCE_HCA_OBJECT);
        uverbs_idr_remove_uobj(uobj);

        return ret;
}

static void alloc_abort_fd_uobject(struct ib_uobject *uobj)
{
        struct ib_uobject_file *uobj_file =
                container_of(uobj, struct ib_uobject_file, uobj);
        struct file *filp = uobj->object;
        int id = uobj_file->uobj.id;

        /* Unsuccessful NEW */
        fput(filp);
        put_unused_fd(id);
}

static int __must_check remove_commit_fd_uobject(struct ib_uobject *uobj,
                                                 enum rdma_remove_reason why)
{
        const struct uverbs_obj_fd_type *fd_type =
                container_of(uobj->type, struct uverbs_obj_fd_type, type);
        struct ib_uobject_file *uobj_file =
                container_of(uobj, struct ib_uobject_file, uobj);
        int ret = fd_type->context_closed(uobj_file, why);

        if (why == RDMA_REMOVE_DESTROY && ret)
                return ret;

        if (why == RDMA_REMOVE_DURING_CLEANUP) {
                alloc_abort_fd_uobject(uobj);
                return ret;
        }

        uobj_file->uobj.context = NULL;
        return ret;
}

static void assert_uverbs_usecnt(struct ib_uobject *uobj, bool exclusive)
{
#ifdef CONFIG_LOCKDEP
        if (exclusive)
                WARN_ON(atomic_read(&uobj->usecnt) != -1);
        else
                WARN_ON(atomic_read(&uobj->usecnt) <= 0);
#endif
}

static int __must_check _rdma_remove_commit_uobject(struct ib_uobject *uobj,
                                                    enum rdma_remove_reason why)
{
        int ret;
        struct ib_ucontext *ucontext = uobj->context;

        ret = uobj->type->type_class->remove_commit(uobj, why);
        if (ret && why == RDMA_REMOVE_DESTROY) {
                /* We couldn't remove the object, so just unlock the uobject */
                atomic_set(&uobj->usecnt, 0);
                uobj->type->type_class->lookup_put(uobj, true);
        } else {
                mutex_lock(&ucontext->uobjects_lock);
                list_del(&uobj->list);
                mutex_unlock(&ucontext->uobjects_lock);
                /* put the ref we took when we created the object */
                uverbs_uobject_put(uobj);
        }

        return ret;
}

/* This is called only for user requested DESTROY reasons */
int __must_check rdma_remove_commit_uobject(struct ib_uobject *uobj)
{
        int ret;
        struct ib_ucontext *ucontext = uobj->context;

        /* put the ref count we took at lookup_get */
        uverbs_uobject_put(uobj);
        /* Cleanup is running. Calling this should have been impossible */
        if (!down_read_trylock(&ucontext->cleanup_rwsem)) {
                WARN(true, "ib_uverbs: Cleanup is running while removing an uobject\n");
                return 0;
        }
        assert_uverbs_usecnt(uobj, true);
        ret = _rdma_remove_commit_uobject(uobj, RDMA_REMOVE_DESTROY);

        up_read(&ucontext->cleanup_rwsem);
        return ret;
}

static int null_obj_type_class_remove_commit(struct ib_uobject *uobj,
                                             enum rdma_remove_reason why)
{
        return 0;
}

static const struct uverbs_obj_type null_obj_type = {
        .type_class = &((const struct uverbs_obj_type_class){
                        .remove_commit = null_obj_type_class_remove_commit,
                        /* be cautious */
                        .needs_kfree_rcu = true}),
};

int rdma_explicit_destroy(struct ib_uobject *uobject)
{
        int ret;
        struct ib_ucontext *ucontext = uobject->context;

        /* Cleanup is running. Calling this should have been impossible */
        if (!down_read_trylock(&ucontext->cleanup_rwsem)) {
                WARN(true, "ib_uverbs: Cleanup is running while removing an uobject\n");
                return 0;
        }
        assert_uverbs_usecnt(uobject, true);
        ret = uobject->type->type_class->remove_commit(uobject,
                                                       RDMA_REMOVE_DESTROY);
        if (ret)
                goto out;

        uobject->type = &null_obj_type;

out:
        up_read(&ucontext->cleanup_rwsem);
        return ret;
}

static void alloc_commit_idr_uobject(struct ib_uobject *uobj)
{
        spin_lock(&uobj->context->ufile->idr_lock);
        /*
         * We already allocated this IDR with a NULL object, so
         * this shouldn't fail.
         */
        WARN_ON(idr_replace(&uobj->context->ufile->idr,
                            uobj, uobj->id));
        spin_unlock(&uobj->context->ufile->idr_lock);
}

static void alloc_commit_fd_uobject(struct ib_uobject *uobj)
{
        struct ib_uobject_file *uobj_file =
                container_of(uobj, struct ib_uobject_file, uobj);

        fd_install(uobj_file->uobj.id, uobj->object);
        /* This shouldn't be used anymore. Use the file object instead */
        uobj_file->uobj.id = 0;
        /* Get another reference as we export this to the fops */
        uverbs_uobject_get(&uobj_file->uobj);
}

int rdma_alloc_commit_uobject(struct ib_uobject *uobj)
{
        /* Cleanup is running. Calling this should have been impossible */
        if (!down_read_trylock(&uobj->context->cleanup_rwsem)) {
                int ret;

                WARN(true, "ib_uverbs: Cleanup is running while allocating an uobject\n");
                ret = uobj->type->type_class->remove_commit(uobj,
                                                            RDMA_REMOVE_DURING_CLEANUP);
                if (ret)
                        pr_warn("ib_uverbs: cleanup of idr object %d failed\n",
                                uobj->id);
                return ret;
        }

        /* matches atomic_set(-1) in alloc_uobj */
        assert_uverbs_usecnt(uobj, true);
        atomic_set(&uobj->usecnt, 0);

        mutex_lock(&uobj->context->uobjects_lock);
        list_add(&uobj->list, &uobj->context->uobjects);
        mutex_unlock(&uobj->context->uobjects_lock);

        uobj->type->type_class->alloc_commit(uobj);
        up_read(&uobj->context->cleanup_rwsem);

        return 0;
}

static void alloc_abort_idr_uobject(struct ib_uobject *uobj)
{
        uverbs_idr_remove_uobj(uobj);
        ib_rdmacg_uncharge(&uobj->cg_obj, uobj->context->device,
                           RDMACG_RESOURCE_HCA_OBJECT);
        uverbs_uobject_put(uobj);
}

void rdma_alloc_abort_uobject(struct ib_uobject *uobj)
{
        uobj->type->type_class->alloc_abort(uobj);
}

static void lookup_put_idr_uobject(struct ib_uobject *uobj, bool exclusive)
{
}

static void lookup_put_fd_uobject(struct ib_uobject *uobj, bool exclusive)
{
        struct file *filp = uobj->object;

        WARN_ON(exclusive);
        /* This indirectly calls uverbs_close_fd and free the object */
        fput(filp);
}

void rdma_lookup_put_uobject(struct ib_uobject *uobj, bool exclusive)
{
        assert_uverbs_usecnt(uobj, exclusive);
        uobj->type->type_class->lookup_put(uobj, exclusive);
        /*
         * In order to unlock an object, either decrease its usecnt for
         * read access or zero it in case of exclusive access. See
         * uverbs_try_lock_object for locking schema information.
         */
        if (!exclusive)
                atomic_dec(&uobj->usecnt);
        else
                atomic_set(&uobj->usecnt, 0);

        uverbs_uobject_put(uobj);
}

const struct uverbs_obj_type_class uverbs_idr_class = {
        .alloc_begin = alloc_begin_idr_uobject,
        .lookup_get = lookup_get_idr_uobject,
        .alloc_commit = alloc_commit_idr_uobject,
        .alloc_abort = alloc_abort_idr_uobject,
        .lookup_put = lookup_put_idr_uobject,
        .remove_commit = remove_commit_idr_uobject,
        /*
         * When we destroy an object, we first just lock it for WRITE and
         * actually DESTROY it in the finalize stage. So, the problematic
         * scenario is when we just started the finalize stage of the
         * destruction (nothing was executed yet). Now, the other thread
         * fetched the object for READ access, but it didn't lock it yet.
         * The DESTROY thread continues and starts destroying the object.
         * When the other thread continue - without the RCU, it would
         * access freed memory. However, the rcu_read_lock delays the free
         * until the rcu_read_lock of the READ operation quits. Since the
         * exclusive lock of the object is still taken by the DESTROY flow, the
         * READ operation will get -EBUSY and it'll just bail out.
         */
        .needs_kfree_rcu = true,
};

static void _uverbs_close_fd(struct ib_uobject_file *uobj_file)
{
        struct ib_ucontext *ucontext;
        struct ib_uverbs_file *ufile = uobj_file->ufile;
        int ret;

        mutex_lock(&uobj_file->ufile->cleanup_mutex);

        /* uobject was either already cleaned up or is cleaned up right now anyway */
        if (!uobj_file->uobj.context ||
            !down_read_trylock(&uobj_file->uobj.context->cleanup_rwsem))
                goto unlock;

        ucontext = uobj_file->uobj.context;
        ret = _rdma_remove_commit_uobject(&uobj_file->uobj, RDMA_REMOVE_CLOSE);
        up_read(&ucontext->cleanup_rwsem);
        if (ret)
                pr_warn("uverbs: unable to clean up uobject file in uverbs_close_fd.\n");
unlock:
        mutex_unlock(&ufile->cleanup_mutex);
}

void uverbs_close_fd(struct file *f)
{
        struct ib_uobject_file *uobj_file = f->private_data;
        struct kref *uverbs_file_ref = &uobj_file->ufile->ref;

        _uverbs_close_fd(uobj_file);
        uverbs_uobject_put(&uobj_file->uobj);
        kref_put(uverbs_file_ref, ib_uverbs_release_file);
}

void uverbs_cleanup_ucontext(struct ib_ucontext *ucontext, bool device_removed)
{
        enum rdma_remove_reason reason = device_removed ?
                RDMA_REMOVE_DRIVER_REMOVE : RDMA_REMOVE_CLOSE;
        unsigned int cur_order = 0;

        ucontext->cleanup_reason = reason;
        /*
         * Waits for all remove_commit and alloc_commit to finish. Logically, We
         * want to hold this forever as the context is going to be destroyed,
         * but we'll release it since it causes a "held lock freed" BUG message.
         */
        down_write(&ucontext->cleanup_rwsem);

        while (!list_empty(&ucontext->uobjects)) {
                struct ib_uobject *obj, *next_obj;
                unsigned int next_order = UINT_MAX;

                /*
                 * This shouldn't run while executing other commands on this
                 * context. Thus, the only thing we should take care of is
                 * releasing a FD while traversing this list. The FD could be
                 * closed and released from the _release fop of this FD.
                 * In order to mitigate this, we add a lock.
                 * We take and release the lock per order traversal in order
                 * to let other threads (which might still use the FDs) chance
                 * to run.
                 */
                mutex_lock(&ucontext->uobjects_lock);
                list_for_each_entry_safe(obj, next_obj, &ucontext->uobjects,
                                         list) {
                        if (obj->type->destroy_order == cur_order) {
                                int ret;

                                /*
                                 * if we hit this WARN_ON, that means we are
                                 * racing with a lookup_get.
                                 */
                                WARN_ON(uverbs_try_lock_object(obj, true));
                                ret = obj->type->type_class->remove_commit(obj,
                                                                           reason);
                                list_del(&obj->list);
                                if (ret)
                                        pr_warn("ib_uverbs: failed to remove uobject id %d order %u\n",
                                                obj->id, cur_order);
                                /* put the ref we took when we created the object */
                                uverbs_uobject_put(obj);
                        } else {
                                next_order = min(next_order,
                                                 obj->type->destroy_order);
                        }
                }
                mutex_unlock(&ucontext->uobjects_lock);
                cur_order = next_order;
        }
        up_write(&ucontext->cleanup_rwsem);
}

void uverbs_initialize_ucontext(struct ib_ucontext *ucontext)
{
        ucontext->cleanup_reason = 0;
        mutex_init(&ucontext->uobjects_lock);
        INIT_LIST_HEAD(&ucontext->uobjects);
        init_rwsem(&ucontext->cleanup_rwsem);
}

const struct uverbs_obj_type_class uverbs_fd_class = {
        .alloc_begin = alloc_begin_fd_uobject,
        .lookup_get = lookup_get_fd_uobject,
        .alloc_commit = alloc_commit_fd_uobject,
        .alloc_abort = alloc_abort_fd_uobject,
        .lookup_put = lookup_put_fd_uobject,
        .remove_commit = remove_commit_fd_uobject,
        .needs_kfree_rcu = false,
};

struct ib_uobject *uverbs_get_uobject_from_context(const struct uverbs_obj_type *type_attrs,
                                                   struct ib_ucontext *ucontext,
                                                   enum uverbs_obj_access access,
                                                   int id)
{
        switch (access) {
        case UVERBS_ACCESS_READ:
                return rdma_lookup_get_uobject(type_attrs, ucontext, id, false);
        case UVERBS_ACCESS_DESTROY:
        case UVERBS_ACCESS_WRITE:
                return rdma_lookup_get_uobject(type_attrs, ucontext, id, true);
        case UVERBS_ACCESS_NEW:
                return rdma_alloc_begin_uobject(type_attrs, ucontext);
        default:
                WARN_ON(true);
                return ERR_PTR(-EOPNOTSUPP);
        }
}

int uverbs_finalize_object(struct ib_uobject *uobj,
                           enum uverbs_obj_access access,
                           bool commit)
{
        int ret = 0;

        /*
         * refcounts should be handled at the object level and not at the
         * uobject level. Refcounts of the objects themselves are done in
         * handlers.
         */

        switch (access) {
        case UVERBS_ACCESS_READ:
                rdma_lookup_put_uobject(uobj, false);
                break;
        case UVERBS_ACCESS_WRITE:
                rdma_lookup_put_uobject(uobj, true);
                break;
        case UVERBS_ACCESS_DESTROY:
                if (commit)
                        ret = rdma_remove_commit_uobject(uobj);
                else
                        rdma_lookup_put_uobject(uobj, true);
                break;
        case UVERBS_ACCESS_NEW:
                if (commit)
                        ret = rdma_alloc_commit_uobject(uobj);
                else
                        rdma_alloc_abort_uobject(uobj);
                break;
        default:
                WARN_ON(true);
                ret = -EOPNOTSUPP;
        }

        return ret;
}

int uverbs_finalize_objects(struct uverbs_attr_bundle *attrs_bundle,
                            struct uverbs_attr_spec_hash * const *spec_hash,
                            size_t num,
                            bool commit)
{
        unsigned int i;
        int ret = 0;

        for (i = 0; i < num; i++) {
                struct uverbs_attr_bundle_hash *curr_bundle =
                        &attrs_bundle->hash[i];
                const struct uverbs_attr_spec_hash *curr_spec_bucket =
                        spec_hash[i];
                unsigned int j;

                for (j = 0; j < curr_bundle->num_attrs; j++) {
                        struct uverbs_attr *attr;
                        const struct uverbs_attr_spec *spec;

                        if (!uverbs_attr_is_valid_in_hash(curr_bundle, j))
                                continue;

                        attr = &curr_bundle->attrs[j];
                        spec = &curr_spec_bucket->attrs[j];

                        if (spec->type == UVERBS_ATTR_TYPE_IDR ||
                            spec->type == UVERBS_ATTR_TYPE_FD) {
                                int current_ret;

                                current_ret = uverbs_finalize_object(attr->obj_attr.uobject,
                                                                     spec->obj.access,
                                                                     commit);
                                if (!ret)
                                        ret = current_ret;
                        }
                }
        }
        return ret;
}