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![Jason Gunthorpe](/assets/img/avatar_default.png)
mlx5 has an ugly flow where it tries to allocate a new MR and replace the existing MR in the same memory during rereg. This is very complicated and buggy. Instead of trying to replace in-place inside the driver, provide support from uverbs to change the entire HW object assigned to a handle during rereg_mr. Since destroying a MR is allowed to fail (ie if a MW is pointing at it) and can't be detected in advance, the algorithm creates a completely new uobject to hold the new MR and swaps the IDR entries of the two objects. The old MR in the temporary IDR entry is destroyed, and if it fails rereg_mr succeeds and destruction is deferred to FD release. This complexity is why this cannot live in a driver safely. Link: https://lore.kernel.org/r/20201130075839.278575-4-leon@kernel.org Signed-off-by: Leon Romanovsky <leonro@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
184 lines
6.1 KiB
C
184 lines
6.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
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/*
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* Copyright (c) 2017, Mellanox Technologies inc. All rights reserved.
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*/
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#ifndef _UVERBS_TYPES_
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#define _UVERBS_TYPES_
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#include <linux/kernel.h>
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#include <rdma/ib_verbs.h>
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struct uverbs_obj_type;
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struct uverbs_api_object;
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enum rdma_lookup_mode {
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UVERBS_LOOKUP_READ,
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UVERBS_LOOKUP_WRITE,
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/*
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* Destroy is like LOOKUP_WRITE, except that the uobject is not
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* locked. uobj_destroy is used to convert a LOOKUP_DESTROY lock into
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* a LOOKUP_WRITE lock.
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*/
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UVERBS_LOOKUP_DESTROY,
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};
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/*
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* The following sequences are valid:
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* Success flow:
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* alloc_begin
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* alloc_commit
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* [..]
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* Access flow:
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* lookup_get(exclusive=false) & uverbs_try_lock_object
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* lookup_put(exclusive=false) via rdma_lookup_put_uobject
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* Destruction flow:
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* lookup_get(exclusive=true) & uverbs_try_lock_object
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* remove_commit
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* remove_handle (optional)
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* lookup_put(exclusive=true) via rdma_lookup_put_uobject
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*
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* Allocate Error flow #1
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* alloc_begin
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* alloc_abort
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* Allocate Error flow #2
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* alloc_begin
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* remove_commit
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* alloc_abort
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* Allocate Error flow #3
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* alloc_begin
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* alloc_commit (fails)
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* remove_commit
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* alloc_abort
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*
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* In all cases the caller must hold the ufile kref until alloc_commit or
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* alloc_abort returns.
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*/
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struct uverbs_obj_type_class {
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struct ib_uobject *(*alloc_begin)(const struct uverbs_api_object *obj,
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struct uverbs_attr_bundle *attrs);
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/* This consumes the kref on uobj */
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void (*alloc_commit)(struct ib_uobject *uobj);
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/* This does not consume the kref on uobj */
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void (*alloc_abort)(struct ib_uobject *uobj);
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struct ib_uobject *(*lookup_get)(const struct uverbs_api_object *obj,
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struct ib_uverbs_file *ufile, s64 id,
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enum rdma_lookup_mode mode);
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void (*lookup_put)(struct ib_uobject *uobj, enum rdma_lookup_mode mode);
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/* This does not consume the kref on uobj */
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int __must_check (*destroy_hw)(struct ib_uobject *uobj,
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enum rdma_remove_reason why,
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struct uverbs_attr_bundle *attrs);
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void (*remove_handle)(struct ib_uobject *uobj);
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void (*swap_uobjects)(struct ib_uobject *obj_old,
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struct ib_uobject *obj_new);
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};
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struct uverbs_obj_type {
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const struct uverbs_obj_type_class * const type_class;
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size_t obj_size;
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};
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/*
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* Objects type classes which support a detach state (object is still alive but
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* it's not attached to any context need to make sure:
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* (a) no call through to a driver after a detach is called
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* (b) detach isn't called concurrently with context_cleanup
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*/
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struct uverbs_obj_idr_type {
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/*
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* In idr based objects, uverbs_obj_type_class points to a generic
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* idr operations. In order to specialize the underlying types (e.g. CQ,
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* QPs, etc.), we add destroy_object specific callbacks.
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*/
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struct uverbs_obj_type type;
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/* Free driver resources from the uobject, make the driver uncallable,
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* and move the uobject to the detached state. If the object was
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* destroyed by the user's request, a failure should leave the uobject
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* completely unchanged.
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*/
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int __must_check (*destroy_object)(struct ib_uobject *uobj,
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enum rdma_remove_reason why,
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struct uverbs_attr_bundle *attrs);
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};
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struct ib_uobject *rdma_lookup_get_uobject(const struct uverbs_api_object *obj,
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struct ib_uverbs_file *ufile, s64 id,
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enum rdma_lookup_mode mode,
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struct uverbs_attr_bundle *attrs);
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void rdma_lookup_put_uobject(struct ib_uobject *uobj,
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enum rdma_lookup_mode mode);
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struct ib_uobject *rdma_alloc_begin_uobject(const struct uverbs_api_object *obj,
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struct uverbs_attr_bundle *attrs);
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void rdma_alloc_abort_uobject(struct ib_uobject *uobj,
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struct uverbs_attr_bundle *attrs,
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bool hw_obj_valid);
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void rdma_alloc_commit_uobject(struct ib_uobject *uobj,
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struct uverbs_attr_bundle *attrs);
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void rdma_assign_uobject(struct ib_uobject *to_uobj,
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struct ib_uobject *new_uobj,
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struct uverbs_attr_bundle *attrs);
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/*
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* uverbs_uobject_get is called in order to increase the reference count on
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* an uobject. This is useful when a handler wants to keep the uobject's memory
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* alive, regardless if this uobject is still alive in the context's objects
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* repository. Objects are put via uverbs_uobject_put.
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*/
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static inline void uverbs_uobject_get(struct ib_uobject *uobject)
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{
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kref_get(&uobject->ref);
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}
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void uverbs_uobject_put(struct ib_uobject *uobject);
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struct uverbs_obj_fd_type {
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/*
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* In fd based objects, uverbs_obj_type_ops points to generic
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* fd operations. In order to specialize the underlying types (e.g.
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* completion_channel), we use fops, name and flags for fd creation.
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* destroy_object is called when the uobject is to be destroyed,
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* because the driver is removed or the FD is closed.
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*/
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struct uverbs_obj_type type;
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void (*destroy_object)(struct ib_uobject *uobj,
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enum rdma_remove_reason why);
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const struct file_operations *fops;
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const char *name;
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int flags;
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};
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extern const struct uverbs_obj_type_class uverbs_idr_class;
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extern const struct uverbs_obj_type_class uverbs_fd_class;
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int uverbs_uobject_fd_release(struct inode *inode, struct file *filp);
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#define UVERBS_BUILD_BUG_ON(cond) (sizeof(char[1 - 2 * !!(cond)]) - \
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sizeof(char))
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#define UVERBS_TYPE_ALLOC_FD(_obj_size, _destroy_object, _fops, _name, _flags) \
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((&((const struct uverbs_obj_fd_type) \
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{.type = { \
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.type_class = &uverbs_fd_class, \
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.obj_size = (_obj_size) + \
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UVERBS_BUILD_BUG_ON((_obj_size) < \
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sizeof(struct ib_uobject)), \
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}, \
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.destroy_object = _destroy_object, \
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.fops = _fops, \
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.name = _name, \
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.flags = _flags}))->type)
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#define UVERBS_TYPE_ALLOC_IDR_SZ(_size, _destroy_object) \
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((&((const struct uverbs_obj_idr_type) \
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{.type = { \
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.type_class = &uverbs_idr_class, \
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.obj_size = (_size) + \
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UVERBS_BUILD_BUG_ON((_size) < \
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sizeof(struct ib_uobject)) \
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}, \
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.destroy_object = _destroy_object,}))->type)
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#define UVERBS_TYPE_ALLOC_IDR(_destroy_object) \
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UVERBS_TYPE_ALLOC_IDR_SZ(sizeof(struct ib_uobject), \
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_destroy_object)
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#endif
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