On Mon, 26 Jun 2023 14:02:45 +0200
Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> wrote:
> Move code drm_gem_shmem_{get,put}_pages() code to
> drm_gem_shmem_{pin,unpin}_locked().
After having a closer look at 'Add generic memory shrinker to VirtIO-GPU
and Panfrost DRM drivers', I realize that's not what we want. We must
differentiate hard-pinning (as in, can't be evicted until all users
give up the ref they have) and soft-pinning (users can survive a
swapout, basically userspace mappings created through
drm_gem_shmem_mmap()).
>
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Cc: Emil Velikov <emil.l.velikov@xxxxxxxxx>
> Cc: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_gem_shmem_helper.c | 108 ++++++++++---------------
> 1 file changed, 41 insertions(+), 67 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> index d6fc034164c0..f406556e42e0 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -128,46 +128,7 @@ struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t
> }
> EXPORT_SYMBOL_GPL(drm_gem_shmem_create);
>
> -static void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem);
> -
> -/**
> - * drm_gem_shmem_free - Free resources associated with a shmem GEM object
> - * @shmem: shmem GEM object to free
> - *
> - * This function cleans up the GEM object state and frees the memory used to
> - * store the object itself.
> - */
> -void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
> -{
> - struct drm_gem_object *obj = &shmem->base;
> -
> - if (obj->import_attach) {
> - drm_prime_gem_destroy(obj, shmem->sgt);
> - } else {
> - dma_resv_lock(shmem->base.resv, NULL);
> -
> - drm_WARN_ON(obj->dev, shmem->vmap_use_count);
> -
> - if (shmem->sgt) {
> - dma_unmap_sgtable(obj->dev->dev, shmem->sgt,
> - DMA_BIDIRECTIONAL, 0);
> - sg_free_table(shmem->sgt);
> - kfree(shmem->sgt);
> - }
> - if (shmem->pages)
> - drm_gem_shmem_put_pages(shmem);
> -
> - drm_WARN_ON(obj->dev, shmem->pages_use_count);
> -
> - dma_resv_unlock(shmem->base.resv);
> - }
> -
> - drm_gem_object_release(obj);
> - kfree(shmem);
> -}
> -EXPORT_SYMBOL_GPL(drm_gem_shmem_free);
> -
> -static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
> +static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
> {
> struct drm_gem_object *obj = &shmem->base;
> struct page **pages;
> @@ -200,13 +161,7 @@ static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
> return 0;
> }
>
> -/*
> - * drm_gem_shmem_put_pages - Decrease use count on the backing pages for a shmem GEM object
> - * @shmem: shmem GEM object
> - *
> - * This function decreases the use count and puts the backing pages when use drops to zero.
> - */
> -static void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
> +static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
> {
> struct drm_gem_object *obj = &shmem->base;
>
> @@ -229,23 +184,42 @@ static void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
> shmem->pages = NULL;
> }
>
> -static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
> +/**
> + * drm_gem_shmem_free - Free resources associated with a shmem GEM object
> + * @shmem: shmem GEM object to free
> + *
> + * This function cleans up the GEM object state and frees the memory used to
> + * store the object itself.
> + */
> +void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
> {
> - int ret;
> + struct drm_gem_object *obj = &shmem->base;
>
> - dma_resv_assert_held(shmem->base.resv);
> + if (obj->import_attach) {
> + drm_prime_gem_destroy(obj, shmem->sgt);
> + } else {
> + dma_resv_lock(shmem->base.resv, NULL);
>
> - ret = drm_gem_shmem_get_pages(shmem);
> + drm_WARN_ON(obj->dev, shmem->vmap_use_count);
>
> - return ret;
> -}
> -
> -static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
> -{
> - dma_resv_assert_held(shmem->base.resv);
> -
> - drm_gem_shmem_put_pages(shmem);
> + if (shmem->sgt) {
> + dma_unmap_sgtable(obj->dev->dev, shmem->sgt,
> + DMA_BIDIRECTIONAL, 0);
> + sg_free_table(shmem->sgt);
> + kfree(shmem->sgt);
> + }
> + if (shmem->pages)
> + drm_gem_shmem_unpin_locked(shmem);
> +
> + drm_WARN_ON(obj->dev, shmem->pages_use_count);
> +
> + dma_resv_unlock(shmem->base.resv);
> + }
> +
> + drm_gem_object_release(obj);
> + kfree(shmem);
> }
> +EXPORT_SYMBOL_GPL(drm_gem_shmem_free);
>
> /**
> * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
> @@ -332,7 +306,7 @@ int drm_gem_shmem_vmap(struct drm_gem_shmem_object *shmem,
> return 0;
> }
>
> - ret = drm_gem_shmem_get_pages(shmem);
> + ret = drm_gem_shmem_pin_locked(shmem);
> if (ret)
> goto err_zero_use;
>
> @@ -355,7 +329,7 @@ int drm_gem_shmem_vmap(struct drm_gem_shmem_object *shmem,
>
> err_put_pages:
> if (!obj->import_attach)
> - drm_gem_shmem_put_pages(shmem);
> + drm_gem_shmem_unpin_locked(shmem);
> err_zero_use:
> shmem->vmap_use_count = 0;
>
> @@ -392,7 +366,7 @@ void drm_gem_shmem_vunmap(struct drm_gem_shmem_object *shmem,
> return;
>
> vunmap(shmem->vaddr);
> - drm_gem_shmem_put_pages(shmem);
> + drm_gem_shmem_unpin_locked(shmem);
> }
>
> shmem->vaddr = NULL;
> @@ -452,7 +426,7 @@ void drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem)
> kfree(shmem->sgt);
> shmem->sgt = NULL;
>
> - drm_gem_shmem_put_pages(shmem);
> + drm_gem_shmem_unpin_locked(shmem);
>
> shmem->madv = -1;
>
> @@ -565,7 +539,7 @@ static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
> struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
>
> dma_resv_lock(shmem->base.resv, NULL);
> - drm_gem_shmem_put_pages(shmem);
> + drm_gem_shmem_unpin_locked(shmem);
> dma_resv_unlock(shmem->base.resv);
>
> drm_gem_vm_close(vma);
> @@ -606,7 +580,7 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct
> }
>
> dma_resv_lock(shmem->base.resv, NULL);
> - ret = drm_gem_shmem_get_pages(shmem);
> + ret = drm_gem_shmem_pin_locked(shmem);
> dma_resv_unlock(shmem->base.resv);
>
> if (ret)
> @@ -674,7 +648,7 @@ static struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_
>
> drm_WARN_ON(obj->dev, obj->import_attach);
>
> - ret = drm_gem_shmem_get_pages(shmem);
> + ret = drm_gem_shmem_pin_locked(shmem);
> if (ret)
> return ERR_PTR(ret);
>
> @@ -696,7 +670,7 @@ static struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_
> sg_free_table(sgt);
> kfree(sgt);
> err_put_pages:
> - drm_gem_shmem_put_pages(shmem);
> + drm_gem_shmem_unpin_locked(shmem);
> return ERR_PTR(ret);
> }
>
