[PATCH] drm/ttm/amdgpu: consolidate ttm reserve paths
Christian König
christian.koenig at amd.com
Wed Jul 29 10:55:37 UTC 2020
Am 28.07.20 um 21:11 schrieb Dave Airlie:
> From: Dave Airlie <airlied at redhat.com>
>
> Drop the WARN_ON and consolidate the two paths into one.
>
> Use the consolidate slowpath in the execbuf utils code.
>
> Signed-off-by: Dave Airlie <airlied at redhat.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_object.h | 2 +-
> drivers/gpu/drm/ttm/ttm_execbuf_util.c | 12 +--
> include/drm/ttm/ttm_bo_driver.h | 91 ++++------------------
> 3 files changed, 20 insertions(+), 85 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
> index afa5189dba7d..e01e8903741e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
> @@ -160,7 +160,7 @@ static inline int amdgpu_bo_reserve(struct amdgpu_bo *bo, bool no_intr)
> struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
> int r;
>
> - r = __ttm_bo_reserve(&bo->tbo, !no_intr, false, NULL);
> + r = ttm_bo_reserve(&bo->tbo, !no_intr, false, NULL);
> if (unlikely(r != 0)) {
> if (r != -ERESTARTSYS)
> dev_err(adev->dev, "%p reserve failed\n", bo);
> diff --git a/drivers/gpu/drm/ttm/ttm_execbuf_util.c b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
> index 1797f04c0534..8a8f1a6a83a6 100644
> --- a/drivers/gpu/drm/ttm/ttm_execbuf_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_execbuf_util.c
> @@ -93,7 +93,7 @@ int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
> list_for_each_entry(entry, list, head) {
> struct ttm_buffer_object *bo = entry->bo;
>
> - ret = __ttm_bo_reserve(bo, intr, (ticket == NULL), ticket);
> + ret = ttm_bo_reserve(bo, intr, (ticket == NULL), ticket);
> if (ret == -EALREADY && dups) {
> struct ttm_validate_buffer *safe = entry;
> entry = list_prev_entry(entry, head);
> @@ -119,13 +119,7 @@ int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
> ttm_eu_backoff_reservation_reverse(list, entry);
>
> if (ret == -EDEADLK) {
> - if (intr) {
> - ret = dma_resv_lock_slow_interruptible(bo->base.resv,
> - ticket);
> - } else {
> - dma_resv_lock_slow(bo->base.resv, ticket);
> - ret = 0;
> - }
> + ret = ttm_bo_reserve_slowpath(bo, intr, ticket);
> }
The extra {} could be removed here as well, apart from that the patch is
Reviewed-by: Christian König <christian.koenig at amd.com>.
Regards,
Christian.
>
> if (!ret && entry->num_shared)
> @@ -133,8 +127,6 @@ int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
> entry->num_shared);
>
> if (unlikely(ret != 0)) {
> - if (ret == -EINTR)
> - ret = -ERESTARTSYS;
> if (ticket) {
> ww_acquire_done(ticket);
> ww_acquire_fini(ticket);
> diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
> index 5a37f1cc057e..bfa9d146d3d4 100644
> --- a/include/drm/ttm/ttm_bo_driver.h
> +++ b/include/drm/ttm/ttm_bo_driver.h
> @@ -597,29 +597,30 @@ int ttm_mem_io_lock(struct ttm_mem_type_manager *man, bool interruptible);
> void ttm_mem_io_unlock(struct ttm_mem_type_manager *man);
>
> /**
> - * __ttm_bo_reserve:
> + * ttm_bo_reserve:
> *
> * @bo: A pointer to a struct ttm_buffer_object.
> * @interruptible: Sleep interruptible if waiting.
> * @no_wait: Don't sleep while trying to reserve, rather return -EBUSY.
> * @ticket: ticket used to acquire the ww_mutex.
> *
> - * Will not remove reserved buffers from the lru lists.
> - * Otherwise identical to ttm_bo_reserve.
> + * Locks a buffer object for validation. (Or prevents other processes from
> + * locking it for validation), while taking a number of measures to prevent
> + * deadlocks.
> *
> * Returns:
> * -EDEADLK: The reservation may cause a deadlock.
> * Release all buffer reservations, wait for @bo to become unreserved and
> - * try again. (only if use_sequence == 1).
> + * try again.
> * -ERESTARTSYS: A wait for the buffer to become unreserved was interrupted by
> * a signal. Release all buffer reservations and return to user-space.
> * -EBUSY: The function needed to sleep, but @no_wait was true
> * -EALREADY: Bo already reserved using @ticket. This error code will only
> * be returned if @use_ticket is set to true.
> */
> -static inline int __ttm_bo_reserve(struct ttm_buffer_object *bo,
> - bool interruptible, bool no_wait,
> - struct ww_acquire_ctx *ticket)
> +static inline int ttm_bo_reserve(struct ttm_buffer_object *bo,
> + bool interruptible, bool no_wait,
> + struct ww_acquire_ctx *ticket)
> {
> int ret = 0;
>
> @@ -641,59 +642,6 @@ static inline int __ttm_bo_reserve(struct ttm_buffer_object *bo,
> return ret;
> }
>
> -/**
> - * ttm_bo_reserve:
> - *
> - * @bo: A pointer to a struct ttm_buffer_object.
> - * @interruptible: Sleep interruptible if waiting.
> - * @no_wait: Don't sleep while trying to reserve, rather return -EBUSY.
> - * @ticket: ticket used to acquire the ww_mutex.
> - *
> - * Locks a buffer object for validation. (Or prevents other processes from
> - * locking it for validation) and removes it from lru lists, while taking
> - * a number of measures to prevent deadlocks.
> - *
> - * Deadlocks may occur when two processes try to reserve multiple buffers in
> - * different order, either by will or as a result of a buffer being evicted
> - * to make room for a buffer already reserved. (Buffers are reserved before
> - * they are evicted). The following algorithm prevents such deadlocks from
> - * occurring:
> - * Processes attempting to reserve multiple buffers other than for eviction,
> - * (typically execbuf), should first obtain a unique 32-bit
> - * validation sequence number,
> - * and call this function with @use_ticket == 1 and @ticket->stamp == the unique
> - * sequence number. If upon call of this function, the buffer object is already
> - * reserved, the validation sequence is checked against the validation
> - * sequence of the process currently reserving the buffer,
> - * and if the current validation sequence is greater than that of the process
> - * holding the reservation, the function returns -EDEADLK. Otherwise it sleeps
> - * waiting for the buffer to become unreserved, after which it retries
> - * reserving.
> - * The caller should, when receiving an -EDEADLK error
> - * release all its buffer reservations, wait for @bo to become unreserved, and
> - * then rerun the validation with the same validation sequence. This procedure
> - * will always guarantee that the process with the lowest validation sequence
> - * will eventually succeed, preventing both deadlocks and starvation.
> - *
> - * Returns:
> - * -EDEADLK: The reservation may cause a deadlock.
> - * Release all buffer reservations, wait for @bo to become unreserved and
> - * try again. (only if use_sequence == 1).
> - * -ERESTARTSYS: A wait for the buffer to become unreserved was interrupted by
> - * a signal. Release all buffer reservations and return to user-space.
> - * -EBUSY: The function needed to sleep, but @no_wait was true
> - * -EALREADY: Bo already reserved using @ticket. This error code will only
> - * be returned if @use_ticket is set to true.
> - */
> -static inline int ttm_bo_reserve(struct ttm_buffer_object *bo,
> - bool interruptible, bool no_wait,
> - struct ww_acquire_ctx *ticket)
> -{
> - WARN_ON(!kref_read(&bo->kref));
> -
> - return __ttm_bo_reserve(bo, interruptible, no_wait, ticket);
> -}
> -
> /**
> * ttm_bo_reserve_slowpath:
> * @bo: A pointer to a struct ttm_buffer_object.
> @@ -708,20 +656,15 @@ static inline int ttm_bo_reserve_slowpath(struct ttm_buffer_object *bo,
> bool interruptible,
> struct ww_acquire_ctx *ticket)
> {
> - int ret = 0;
> -
> - WARN_ON(!kref_read(&bo->kref));
> -
> - if (interruptible)
> - ret = dma_resv_lock_slow_interruptible(bo->base.resv,
> - ticket);
> - else
> - dma_resv_lock_slow(bo->base.resv, ticket);
> -
> - if (ret == -EINTR)
> - ret = -ERESTARTSYS;
> -
> - return ret;
> + if (interruptible) {
> + int ret = dma_resv_lock_slow_interruptible(bo->base.resv,
> + ticket);
> + if (ret == -EINTR)
> + ret = -ERESTARTSYS;
> + return ret;
> + }
> + dma_resv_lock_slow(bo->base.resv, ticket);
> + return 0;
> }
>
> /**
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