![Thomas Hellstrom](/assets/img/avatar_default.png)
Typically when we look up objects under the rcu lock, we take a reference to make sure the returned object pointer is valid. Now provide a function to look up an object and instead of taking a reference to it, keep the rcu lock held when returning the object pointer. This means that the object pointer is valid as long as the rcu lock is held, but the object may be doomed (its refcount may be zero). Any persistent usage of the object pointer outside of the rcu lock requires a reference to be taken using kref_get_unless_zero(). Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> Reviewed-by: Sinclair Yeh <syeh@vmware.com>
376 lines
12 KiB
C
376 lines
12 KiB
C
/**************************************************************************
|
|
*
|
|
* Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
|
|
* All Rights Reserved.
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a
|
|
* copy of this software and associated documentation files (the
|
|
* "Software"), to deal in the Software without restriction, including
|
|
* without limitation the rights to use, copy, modify, merge, publish,
|
|
* distribute, sub license, and/or sell copies of the Software, and to
|
|
* permit persons to whom the Software is furnished to do so, subject to
|
|
* the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice (including the
|
|
* next paragraph) shall be included in all copies or substantial portions
|
|
* of the Software.
|
|
*
|
|
* 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 NON-INFRINGEMENT. IN NO EVENT SHALL
|
|
* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS 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.
|
|
*
|
|
**************************************************************************/
|
|
/*
|
|
* Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
|
|
*/
|
|
/** @file ttm_object.h
|
|
*
|
|
* Base- and reference object implementation for the various
|
|
* ttm objects. Implements reference counting, minimal security checks
|
|
* and release on file close.
|
|
*/
|
|
|
|
#ifndef _TTM_OBJECT_H_
|
|
#define _TTM_OBJECT_H_
|
|
|
|
#include <linux/list.h>
|
|
#include <drm/drm_hashtab.h>
|
|
#include <linux/kref.h>
|
|
#include <linux/rcupdate.h>
|
|
#include <linux/dma-buf.h>
|
|
#include <drm/ttm/ttm_memory.h>
|
|
|
|
/**
|
|
* enum ttm_ref_type
|
|
*
|
|
* Describes what type of reference a ref object holds.
|
|
*
|
|
* TTM_REF_USAGE is a simple refcount on a base object.
|
|
*
|
|
* TTM_REF_SYNCCPU_READ is a SYNCCPU_READ reference on a
|
|
* buffer object.
|
|
*
|
|
* TTM_REF_SYNCCPU_WRITE is a SYNCCPU_WRITE reference on a
|
|
* buffer object.
|
|
*
|
|
*/
|
|
|
|
enum ttm_ref_type {
|
|
TTM_REF_USAGE,
|
|
TTM_REF_SYNCCPU_READ,
|
|
TTM_REF_SYNCCPU_WRITE,
|
|
TTM_REF_NUM
|
|
};
|
|
|
|
/**
|
|
* enum ttm_object_type
|
|
*
|
|
* One entry per ttm object type.
|
|
* Device-specific types should use the
|
|
* ttm_driver_typex types.
|
|
*/
|
|
|
|
enum ttm_object_type {
|
|
ttm_fence_type,
|
|
ttm_buffer_type,
|
|
ttm_lock_type,
|
|
ttm_prime_type,
|
|
ttm_driver_type0 = 256,
|
|
ttm_driver_type1,
|
|
ttm_driver_type2,
|
|
ttm_driver_type3,
|
|
ttm_driver_type4,
|
|
ttm_driver_type5
|
|
};
|
|
|
|
struct ttm_object_file;
|
|
struct ttm_object_device;
|
|
|
|
/**
|
|
* struct ttm_base_object
|
|
*
|
|
* @hash: hash entry for the per-device object hash.
|
|
* @type: derived type this object is base class for.
|
|
* @shareable: Other ttm_object_files can access this object.
|
|
*
|
|
* @tfile: Pointer to ttm_object_file of the creator.
|
|
* NULL if the object was not created by a user request.
|
|
* (kernel object).
|
|
*
|
|
* @refcount: Number of references to this object, not
|
|
* including the hash entry. A reference to a base object can
|
|
* only be held by a ref object.
|
|
*
|
|
* @refcount_release: A function to be called when there are
|
|
* no more references to this object. This function should
|
|
* destroy the object (or make sure destruction eventually happens),
|
|
* and when it is called, the object has
|
|
* already been taken out of the per-device hash. The parameter
|
|
* "base" should be set to NULL by the function.
|
|
*
|
|
* @ref_obj_release: A function to be called when a reference object
|
|
* with another ttm_ref_type than TTM_REF_USAGE is deleted.
|
|
* This function may, for example, release a lock held by a user-space
|
|
* process.
|
|
*
|
|
* This struct is intended to be used as a base struct for objects that
|
|
* are visible to user-space. It provides a global name, race-safe
|
|
* access and refcounting, minimal access contol and hooks for unref actions.
|
|
*/
|
|
|
|
struct ttm_base_object {
|
|
struct rcu_head rhead;
|
|
struct ttm_object_file *tfile;
|
|
struct kref refcount;
|
|
void (*refcount_release) (struct ttm_base_object **base);
|
|
void (*ref_obj_release) (struct ttm_base_object *base,
|
|
enum ttm_ref_type ref_type);
|
|
u32 handle;
|
|
enum ttm_object_type object_type;
|
|
u32 shareable;
|
|
};
|
|
|
|
|
|
/**
|
|
* struct ttm_prime_object - Modified base object that is prime-aware
|
|
*
|
|
* @base: struct ttm_base_object that we derive from
|
|
* @mutex: Mutex protecting the @dma_buf member.
|
|
* @size: Size of the dma_buf associated with this object
|
|
* @real_type: Type of the underlying object. Needed since we're setting
|
|
* the value of @base::object_type to ttm_prime_type
|
|
* @dma_buf: Non ref-coutned pointer to a struct dma_buf created from this
|
|
* object.
|
|
* @refcount_release: The underlying object's release method. Needed since
|
|
* we set @base::refcount_release to our own release method.
|
|
*/
|
|
|
|
struct ttm_prime_object {
|
|
struct ttm_base_object base;
|
|
struct mutex mutex;
|
|
size_t size;
|
|
enum ttm_object_type real_type;
|
|
struct dma_buf *dma_buf;
|
|
void (*refcount_release) (struct ttm_base_object **);
|
|
};
|
|
|
|
/**
|
|
* ttm_base_object_init
|
|
*
|
|
* @tfile: Pointer to a struct ttm_object_file.
|
|
* @base: The struct ttm_base_object to initialize.
|
|
* @shareable: This object is shareable with other applcations.
|
|
* (different @tfile pointers.)
|
|
* @type: The object type.
|
|
* @refcount_release: See the struct ttm_base_object description.
|
|
* @ref_obj_release: See the struct ttm_base_object description.
|
|
*
|
|
* Initializes a struct ttm_base_object.
|
|
*/
|
|
|
|
extern int ttm_base_object_init(struct ttm_object_file *tfile,
|
|
struct ttm_base_object *base,
|
|
bool shareable,
|
|
enum ttm_object_type type,
|
|
void (*refcount_release) (struct ttm_base_object
|
|
**),
|
|
void (*ref_obj_release) (struct ttm_base_object
|
|
*,
|
|
enum ttm_ref_type
|
|
ref_type));
|
|
|
|
/**
|
|
* ttm_base_object_lookup
|
|
*
|
|
* @tfile: Pointer to a struct ttm_object_file.
|
|
* @key: Hash key
|
|
*
|
|
* Looks up a struct ttm_base_object with the key @key.
|
|
*/
|
|
|
|
extern struct ttm_base_object *ttm_base_object_lookup(struct ttm_object_file
|
|
*tfile, uint32_t key);
|
|
|
|
/**
|
|
* ttm_base_object_lookup_for_ref
|
|
*
|
|
* @tdev: Pointer to a struct ttm_object_device.
|
|
* @key: Hash key
|
|
*
|
|
* Looks up a struct ttm_base_object with the key @key.
|
|
* This function should only be used when the struct tfile associated with the
|
|
* caller doesn't yet have a reference to the base object.
|
|
*/
|
|
|
|
extern struct ttm_base_object *
|
|
ttm_base_object_lookup_for_ref(struct ttm_object_device *tdev, uint32_t key);
|
|
|
|
/**
|
|
* ttm_base_object_unref
|
|
*
|
|
* @p_base: Pointer to a pointer referencing a struct ttm_base_object.
|
|
*
|
|
* Decrements the base object refcount and clears the pointer pointed to by
|
|
* p_base.
|
|
*/
|
|
|
|
extern void ttm_base_object_unref(struct ttm_base_object **p_base);
|
|
|
|
/**
|
|
* ttm_ref_object_add.
|
|
*
|
|
* @tfile: A struct ttm_object_file representing the application owning the
|
|
* ref_object.
|
|
* @base: The base object to reference.
|
|
* @ref_type: The type of reference.
|
|
* @existed: Upon completion, indicates that an identical reference object
|
|
* already existed, and the refcount was upped on that object instead.
|
|
* @require_existed: Fail with -EPERM if an identical ref object didn't
|
|
* already exist.
|
|
*
|
|
* Checks that the base object is shareable and adds a ref object to it.
|
|
*
|
|
* Adding a ref object to a base object is basically like referencing the
|
|
* base object, but a user-space application holds the reference. When the
|
|
* file corresponding to @tfile is closed, all its reference objects are
|
|
* deleted. A reference object can have different types depending on what
|
|
* it's intended for. It can be refcounting to prevent object destruction,
|
|
* When user-space takes a lock, it can add a ref object to that lock to
|
|
* make sure the lock is released if the application dies. A ref object
|
|
* will hold a single reference on a base object.
|
|
*/
|
|
extern int ttm_ref_object_add(struct ttm_object_file *tfile,
|
|
struct ttm_base_object *base,
|
|
enum ttm_ref_type ref_type, bool *existed,
|
|
bool require_existed);
|
|
|
|
extern bool ttm_ref_object_exists(struct ttm_object_file *tfile,
|
|
struct ttm_base_object *base);
|
|
|
|
/**
|
|
* ttm_ref_object_base_unref
|
|
*
|
|
* @key: Key representing the base object.
|
|
* @ref_type: Ref type of the ref object to be dereferenced.
|
|
*
|
|
* Unreference a ref object with type @ref_type
|
|
* on the base object identified by @key. If there are no duplicate
|
|
* references, the ref object will be destroyed and the base object
|
|
* will be unreferenced.
|
|
*/
|
|
extern int ttm_ref_object_base_unref(struct ttm_object_file *tfile,
|
|
unsigned long key,
|
|
enum ttm_ref_type ref_type);
|
|
|
|
/**
|
|
* ttm_object_file_init - initialize a struct ttm_object file
|
|
*
|
|
* @tdev: A struct ttm_object device this file is initialized on.
|
|
* @hash_order: Order of the hash table used to hold the reference objects.
|
|
*
|
|
* This is typically called by the file_ops::open function.
|
|
*/
|
|
|
|
extern struct ttm_object_file *ttm_object_file_init(struct ttm_object_device
|
|
*tdev,
|
|
unsigned int hash_order);
|
|
|
|
/**
|
|
* ttm_object_file_release - release data held by a ttm_object_file
|
|
*
|
|
* @p_tfile: Pointer to pointer to the ttm_object_file object to release.
|
|
* *p_tfile will be set to NULL by this function.
|
|
*
|
|
* Releases all data associated by a ttm_object_file.
|
|
* Typically called from file_ops::release. The caller must
|
|
* ensure that there are no concurrent users of tfile.
|
|
*/
|
|
|
|
extern void ttm_object_file_release(struct ttm_object_file **p_tfile);
|
|
|
|
/**
|
|
* ttm_object device init - initialize a struct ttm_object_device
|
|
*
|
|
* @mem_glob: struct ttm_mem_global for memory accounting.
|
|
* @hash_order: Order of hash table used to hash the base objects.
|
|
* @ops: DMA buf ops for prime objects of this device.
|
|
*
|
|
* This function is typically called on device initialization to prepare
|
|
* data structures needed for ttm base and ref objects.
|
|
*/
|
|
|
|
extern struct ttm_object_device *
|
|
ttm_object_device_init(struct ttm_mem_global *mem_glob,
|
|
unsigned int hash_order,
|
|
const struct dma_buf_ops *ops);
|
|
|
|
/**
|
|
* ttm_object_device_release - release data held by a ttm_object_device
|
|
*
|
|
* @p_tdev: Pointer to pointer to the ttm_object_device object to release.
|
|
* *p_tdev will be set to NULL by this function.
|
|
*
|
|
* Releases all data associated by a ttm_object_device.
|
|
* Typically called from driver::unload before the destruction of the
|
|
* device private data structure.
|
|
*/
|
|
|
|
extern void ttm_object_device_release(struct ttm_object_device **p_tdev);
|
|
|
|
#define ttm_base_object_kfree(__object, __base)\
|
|
kfree_rcu(__object, __base.rhead)
|
|
|
|
extern int ttm_prime_object_init(struct ttm_object_file *tfile,
|
|
size_t size,
|
|
struct ttm_prime_object *prime,
|
|
bool shareable,
|
|
enum ttm_object_type type,
|
|
void (*refcount_release)
|
|
(struct ttm_base_object **),
|
|
void (*ref_obj_release)
|
|
(struct ttm_base_object *,
|
|
enum ttm_ref_type ref_type));
|
|
|
|
static inline enum ttm_object_type
|
|
ttm_base_object_type(struct ttm_base_object *base)
|
|
{
|
|
return (base->object_type == ttm_prime_type) ?
|
|
container_of(base, struct ttm_prime_object, base)->real_type :
|
|
base->object_type;
|
|
}
|
|
extern int ttm_prime_fd_to_handle(struct ttm_object_file *tfile,
|
|
int fd, u32 *handle);
|
|
extern int ttm_prime_handle_to_fd(struct ttm_object_file *tfile,
|
|
uint32_t handle, uint32_t flags,
|
|
int *prime_fd);
|
|
|
|
#define ttm_prime_object_kfree(__obj, __prime) \
|
|
kfree_rcu(__obj, __prime.base.rhead)
|
|
|
|
/*
|
|
* Extra memory required by the base object's idr storage, which is allocated
|
|
* separately from the base object itself. We estimate an on-average 128 bytes
|
|
* per idr.
|
|
*/
|
|
#define TTM_OBJ_EXTRA_SIZE 128
|
|
|
|
struct ttm_base_object *
|
|
ttm_base_object_noref_lookup(struct ttm_object_file *tfile, uint32_t key);
|
|
|
|
/**
|
|
* ttm_base_object_noref_release - release a base object pointer looked up
|
|
* without reference
|
|
*
|
|
* Releases a base object pointer looked up with ttm_base_object_noref_lookup().
|
|
*/
|
|
static inline void ttm_base_object_noref_release(void)
|
|
{
|
|
__acquire(RCU);
|
|
rcu_read_unlock();
|
|
}
|
|
#endif
|