forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
107 lines
2.9 KiB
107 lines
2.9 KiB
/* |
|
* Copyright 2019 Advanced Micro Devices, Inc. |
|
* |
|
* 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 COPYRIGHT HOLDER(S) OR AUTHOR(S) 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/semaphore.h> |
|
#include <linux/atomic.h> |
|
|
|
/* |
|
* Reusable 2 PHASE task barrier (randevouz point) implementation for N tasks. |
|
* Based on the Little book of sempahores - https://greenteapress.com/wp/semaphores/ |
|
*/ |
|
|
|
|
|
|
|
#ifndef DRM_TASK_BARRIER_H_ |
|
#define DRM_TASK_BARRIER_H_ |
|
|
|
/* |
|
* Represents an instance of a task barrier. |
|
*/ |
|
struct task_barrier { |
|
unsigned int n; |
|
atomic_t count; |
|
struct semaphore enter_turnstile; |
|
struct semaphore exit_turnstile; |
|
}; |
|
|
|
static inline void task_barrier_signal_turnstile(struct semaphore *turnstile, |
|
unsigned int n) |
|
{ |
|
int i; |
|
|
|
for (i = 0 ; i < n; i++) |
|
up(turnstile); |
|
} |
|
|
|
static inline void task_barrier_init(struct task_barrier *tb) |
|
{ |
|
tb->n = 0; |
|
atomic_set(&tb->count, 0); |
|
sema_init(&tb->enter_turnstile, 0); |
|
sema_init(&tb->exit_turnstile, 0); |
|
} |
|
|
|
static inline void task_barrier_add_task(struct task_barrier *tb) |
|
{ |
|
tb->n++; |
|
} |
|
|
|
static inline void task_barrier_rem_task(struct task_barrier *tb) |
|
{ |
|
tb->n--; |
|
} |
|
|
|
/* |
|
* Lines up all the threads BEFORE the critical point. |
|
* |
|
* When all thread passed this code the entry barrier is back to locked state. |
|
*/ |
|
static inline void task_barrier_enter(struct task_barrier *tb) |
|
{ |
|
if (atomic_inc_return(&tb->count) == tb->n) |
|
task_barrier_signal_turnstile(&tb->enter_turnstile, tb->n); |
|
|
|
down(&tb->enter_turnstile); |
|
} |
|
|
|
/* |
|
* Lines up all the threads AFTER the critical point. |
|
* |
|
* This function is used to avoid any one thread running ahead if the barrier is |
|
* used repeatedly . |
|
*/ |
|
static inline void task_barrier_exit(struct task_barrier *tb) |
|
{ |
|
if (atomic_dec_return(&tb->count) == 0) |
|
task_barrier_signal_turnstile(&tb->exit_turnstile, tb->n); |
|
|
|
down(&tb->exit_turnstile); |
|
} |
|
|
|
/* Convinieince function when nothing to be done in between entry and exit */ |
|
static inline void task_barrier_full(struct task_barrier *tb) |
|
{ |
|
task_barrier_enter(tb); |
|
task_barrier_exit(tb); |
|
} |
|
|
|
#endif
|
|
|