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/*
* Copyright (c) 2017-2018, NVIDIA CORPORATION. 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, sublicense,
* 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 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 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.
*/
/*
* The following structure is used for reference counting of objects in nvgpu.
*/
#ifndef NVGPU_KREF_H
#define NVGPU_KREF_H
#include <nvgpu/atomic.h>
struct nvgpu_ref {
nvgpu_atomic_t refcount;
};
/*
* Initialize object.
* @ref: the nvgpu_ref object to initialize
*/
static inline void nvgpu_ref_init(struct nvgpu_ref *ref)
{
nvgpu_atomic_set(&ref->refcount, 1);
}
/*
* Increment reference count for the object
* @ref: the nvgpu_ref object
*/
static inline void nvgpu_ref_get(struct nvgpu_ref *ref)
{
nvgpu_atomic_inc(&ref->refcount);
}
/*
* Decrement reference count for the object and call release() if it becomes
* zero.
* @ref: the nvgpu_ref object
* @release: pointer to the function that would be invoked to clean up the
* object when the reference count becomes zero, i.e. the last
* reference corresponding to this object is removed.
* Return 1 if object was removed, otherwise return 0. The user should not
* make any assumptions about the status of the object in the memory when
* the function returns 0 and should only use it to know that there are no
* further references to this object.
*/
static inline int nvgpu_ref_put(struct nvgpu_ref *ref,
void (*release)(struct nvgpu_ref *r))
{
if (nvgpu_atomic_sub_and_test(1, &ref->refcount)) {
if (release != NULL) {
release(ref);
}
return 1;
}
return 0;
}
/*
* Increment reference count for the object unless it is zero.
* @ref: the nvgpu_ref object
* Return non-zero if the increment succeeds, Otherwise return 0.
*/
static inline int __must_check nvgpu_ref_get_unless_zero(struct nvgpu_ref *ref)
{
return nvgpu_atomic_add_unless(&ref->refcount, 1, 0);
}
#endif /* NVGPU_KREF_H */
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