Re: [PATCH 1/3] drm/ttm: add ttm_bo_is_reserved

[Thomas Hellstrom <thomas@shipmail.org>]

On 10/12/2012 04:58 PM, Maarten Lankhorst wrote:
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
> ---
>   drivers/gpu/drm/ttm/ttm_bo.c |   12 ++++++------
>   include/drm/ttm/ttm_bo_api.h |   14 ++++++++++++++
>   2 files changed, 20 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
> index be1148e..d9d8541 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -161,9 +161,9 @@ int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo, bool interruptible)
>   {
>   	if (interruptible) {
>   		return wait_event_interruptible(bo->event_queue,
> -					       atomic_read(&bo->reserved) == 0);
> +					       !ttm_bo_is_reserved(bo));
>   	} else {
> -		wait_event(bo->event_queue, atomic_read(&bo->reserved) == 0);
> +		wait_event(bo->event_queue, !ttm_bo_is_reserved(bo));
>   		return 0;
>   	}
>   }
> @@ -174,7 +174,7 @@ void ttm_bo_add_to_lru(struct ttm_buffer_object *bo)
>   	struct ttm_bo_device *bdev = bo->bdev;
>   	struct ttm_mem_type_manager *man;
>   
> -	BUG_ON(!atomic_read(&bo->reserved));
> +	BUG_ON(!ttm_bo_is_reserved(bo));
>   
>   	if (!(bo->mem.placement & TTM_PL_FLAG_NO_EVICT)) {
>   
> @@ -748,7 +748,7 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo, bool interruptible,
>   		goto out;
>   	}
>   
> -	BUG_ON(!atomic_read(&bo->reserved));
> +	BUG_ON(!ttm_bo_is_reserved(bo));
>   
>   	evict_mem = bo->mem;
>   	evict_mem.mm_node = NULL;
> @@ -1058,7 +1058,7 @@ int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
>   	struct ttm_mem_reg mem;
>   	struct ttm_bo_device *bdev = bo->bdev;
>   
> -	BUG_ON(!atomic_read(&bo->reserved));
> +	BUG_ON(!ttm_bo_is_reserved(bo));
>   
>   	/*
>   	 * FIXME: It's possible to pipeline buffer moves.
> @@ -1115,7 +1115,7 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
>   {
>   	int ret;
>   
> -	BUG_ON(!atomic_read(&bo->reserved));
> +	BUG_ON(!ttm_bo_is_reserved(bo));
>   	/* Check that range is valid */
>   	if (placement->lpfn || placement->fpfn)
>   		if (placement->fpfn > placement->lpfn ||
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index 9654451..1d71f6b 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -705,4 +705,18 @@ extern ssize_t ttm_bo_io(struct ttm_bo_device *bdev, struct file *filp,
>   
>   extern void ttm_bo_swapout_all(struct ttm_bo_device *bdev);
>   
> +/**
> + * ttm_bo_is_reserved - return an indication if a ttm buffer object is reserved
> + *
> + * @bo:     The buffer object to check.
> + *
> + * This function returns an indication if a bo is reserved or not, and should
> + * only be used to print an error when it is not from incorrect api usage, since
> + * there's no guarantee that it is the caller that is holding the reservation.
> + */
> +static inline bool ttm_bo_is_reserved(struct ttm_buffer_object *bo)
> +{
> +	return atomic_read(&bo->reserved);
> +}
> +
>   #endif
This looks good, although for clarity we should add in the comments that
if the caller is holding the reservation, the function is guaranteed to 
return true.

Otherwise
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
>
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