[PATCH 04/16] drm/amdkfd: Short cut for kfd_wait_on_events without waiting

[Oded Gabbay]

On Sat, Oct 21, 2017 at 3:23 AM, Felix Kuehling <Felix.Kuehling at amd.com> wrote:
> From: Sean Keely <sean.keely at amd.com>
>
> If kfd_wait_on_events can return immediately, we don't need to populate
> the wait list and don't need to enter the sleep-loop.
>
> Signed-off-by: Sean Keely <sean.keely at amd.com>
> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
> ---
>  drivers/gpu/drm/amd/amdkfd/kfd_events.c | 43 ++++++++++++++++++++++++++++++---
>  1 file changed, 39 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
> index ade71b7..64cc42c 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_events.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
> @@ -617,7 +617,7 @@ static struct kfd_event_waiter *alloc_event_waiters(uint32_t num_events)
>         return event_waiters;
>  }
>
> -static int init_event_waiter(struct kfd_process *p,
> +static int init_event_waiter_get_status(struct kfd_process *p,
>                 struct kfd_event_waiter *waiter,
>                 uint32_t event_id,
>                 uint32_t input_index)
> @@ -632,11 +632,20 @@ static int init_event_waiter(struct kfd_process *p,
>         waiter->activated = ev->signaled;
>         ev->signaled = ev->signaled && !ev->auto_reset;
>
> -       list_add(&waiter->waiters, &ev->waiters);
> -
>         return 0;
>  }
>
> +static void init_event_waiter_add_to_waitlist(struct kfd_event_waiter *waiter)
> +{
> +       struct kfd_event *ev = waiter->event;
> +
> +       /* Only add to the wait list if we actually need to
> +        * wait on this event.
> +        */
> +       if (!waiter->activated)
> +               list_add(&waiter->waiters, &ev->waiters);
> +}
> +
>  static bool test_event_condition(bool all, uint32_t num_events,
>                                 struct kfd_event_waiter *event_waiters)
>  {
> @@ -724,11 +733,17 @@ int kfd_wait_on_events(struct kfd_process *p,
>                         (struct kfd_event_data __user *) data;
>         uint32_t i;
>         int ret = 0;
> +
>         struct kfd_event_waiter *event_waiters = NULL;
>         long timeout = user_timeout_to_jiffies(user_timeout_ms);
>
>         mutex_lock(&p->event_mutex);
>
> +       /* Set to something unreasonable - this is really
> +        * just a bool for now.
> +        */
> +       *wait_result = KFD_WAIT_TIMEOUT;
> +
>         event_waiters = alloc_event_waiters(num_events);
>         if (!event_waiters) {
>                 ret = -ENOMEM;
> @@ -744,14 +759,34 @@ int kfd_wait_on_events(struct kfd_process *p,
>                         goto fail;
>                 }
>
> -               ret = init_event_waiter(p, &event_waiters[i],
> +               ret = init_event_waiter_get_status(p, &event_waiters[i],
>                                 event_data.event_id, i);
>                 if (ret)
>                         goto fail;
>         }
>
> +       /* Check condition once. */
> +       if (test_event_condition(all, num_events, event_waiters)) {
> +               if (copy_signaled_event_data(num_events,
> +                               event_waiters, events))
> +                       *wait_result = KFD_WAIT_COMPLETE;
> +               else
> +                       *wait_result = KFD_WAIT_ERROR;
> +               free_waiters(num_events, event_waiters);
> +       } else {
> +               /* Add to wait lists if we need to wait. */
> +               for (i = 0; i < num_events; i++)
> +                       init_event_waiter_add_to_waitlist(&event_waiters[i]);
> +       }
> +
>         mutex_unlock(&p->event_mutex);
>
> +       /* Return if all waits were already satisfied. */
> +       if (*wait_result != KFD_WAIT_TIMEOUT) {
> +               __set_current_state(TASK_RUNNING);
> +               return ret;
> +       }
> +
>         while (true) {
>                 if (fatal_signal_pending(current)) {
>                         ret = -EINTR;
> --
> 2.7.4
>

This patch is:
Acked-by: Oded Gabbay <oded.gabbay at gmail.com>