Some typographical error nitpicks inline. On 12/13/19 10:54 AM, Andrey Grodzovsky wrote: > It is used to synchronize N threads at a rendevouz point before execution rendezvous > of critical code that has to be started by all the threads at approximatly approximately > the same time. > > v2: Remove mention of reset use case, improve doc. > > Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx> > --- > include/drm/task_barrier.h | 107 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 107 insertions(+) > create mode 100644 include/drm/task_barrier.h > > diff --git a/include/drm/task_barrier.h b/include/drm/task_barrier.h > new file mode 100644 > index 0000000..087e3f6 > --- /dev/null > +++ b/include/drm/task_barrier.h > @@ -0,0 +1,107 @@ > +/* > + * 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. rendezvous > + * Based on the Little book of sempahores - http://greenteapress.com/semaphores/LittleBookOfSemaphores.pdf 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. threads pass > + */ > +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 */ Convenience > +static inline void task_barrier_full(struct task_barrier *tb) > +{ > + task_barrier_enter(tb); > + task_barrier_exit(tb); > +} > + > +#endif _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
