[PATCH 2/2] drm/vgem: use shmem helpers

Thomas Zimmermann tzimmermann at suse.de
Tue Feb 23 11:19:06 UTC 2021


Hi

Am 23.02.21 um 11:59 schrieb Daniel Vetter:
> Aside from deleting lots of code the real motivation here is to switch
> the mmap over to VM_PFNMAP, to be more consistent with what real gpu
> drivers do. They're all VM_PFNMP, which means get_user_pages doesn't
> work, and even if you try and there's a struct page behind that,
> touching it and mucking around with its refcount can upset drivers
> real bad.
> 
> Cc: John Stultz <john.stultz at linaro.org>
> Cc: Sumit Semwal <sumit.semwal at linaro.org>
> Cc: "Christian König" <christian.koenig at amd.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Melissa Wen <melissa.srw at gmail.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/vgem/vgem_drv.c | 280 +-------------------------------
>   1 file changed, 3 insertions(+), 277 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> index a0e75f1d5d01..88b3d125a610 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.c
> +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> @@ -40,6 +40,7 @@
>   #include <drm/drm_file.h>
>   #include <drm/drm_ioctl.h>
>   #include <drm/drm_managed.h>
> +#include <drm/drm_gem_shmem_helper.h>

This should be between file.h and ioctl.h

>   #include <drm/drm_prime.h>
>   
>   #include "vgem_drv.h"
> @@ -50,27 +51,11 @@
>   #define DRIVER_MAJOR	1
>   #define DRIVER_MINOR	0
>   
> -static const struct drm_gem_object_funcs vgem_gem_object_funcs;
> -
>   static struct vgem_device {
>   	struct drm_device drm;
>   	struct platform_device *platform;
>   } *vgem_device;
>   
> -static void vgem_gem_free_object(struct drm_gem_object *obj)
> -{
> -	struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);
> -
> -	kvfree(vgem_obj->pages);
> -	mutex_destroy(&vgem_obj->pages_lock);
> -
> -	if (obj->import_attach)
> -		drm_prime_gem_destroy(obj, vgem_obj->table);
> -
> -	drm_gem_object_release(obj);
> -	kfree(vgem_obj);
> -}
> -
>   static vm_fault_t vgem_gem_fault(struct vm_fault *vmf)

 From a quick grep it looks like you should be able to remove this 
function and vgam_gem_vm_ops as well.

The rest of the patch looks good to me.

Acked-by: Thomas Zimmermann <tzimmermann at suse.de>

>   {
>   	struct vm_area_struct *vma = vmf->vma;
> @@ -159,265 +144,12 @@ static void vgem_postclose(struct drm_device *dev, struct drm_file *file)
>   	kfree(vfile);
>   }
>   
> -static struct drm_vgem_gem_object *__vgem_gem_create(struct drm_device *dev,
> -						unsigned long size)
> -{
> -	struct drm_vgem_gem_object *obj;
> -	int ret;
> -
> -	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
> -	if (!obj)
> -		return ERR_PTR(-ENOMEM);
> -
> -	obj->base.funcs = &vgem_gem_object_funcs;
> -
> -	ret = drm_gem_object_init(dev, &obj->base, roundup(size, PAGE_SIZE));
> -	if (ret) {
> -		kfree(obj);
> -		return ERR_PTR(ret);
> -	}
> -
> -	mutex_init(&obj->pages_lock);
> -
> -	return obj;
> -}
> -
> -static void __vgem_gem_destroy(struct drm_vgem_gem_object *obj)
> -{
> -	drm_gem_object_release(&obj->base);
> -	kfree(obj);
> -}
> -
> -static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
> -					      struct drm_file *file,
> -					      unsigned int *handle,
> -					      unsigned long size)
> -{
> -	struct drm_vgem_gem_object *obj;
> -	int ret;
> -
> -	obj = __vgem_gem_create(dev, size);
> -	if (IS_ERR(obj))
> -		return ERR_CAST(obj);
> -
> -	ret = drm_gem_handle_create(file, &obj->base, handle);
> -	if (ret) {
> -		drm_gem_object_put(&obj->base);
> -		return ERR_PTR(ret);
> -	}
> -
> -	return &obj->base;
> -}
> -
> -static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
> -				struct drm_mode_create_dumb *args)
> -{
> -	struct drm_gem_object *gem_object;
> -	u64 pitch, size;
> -
> -	pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
> -	size = args->height * pitch;
> -	if (size == 0)
> -		return -EINVAL;
> -
> -	gem_object = vgem_gem_create(dev, file, &args->handle, size);
> -	if (IS_ERR(gem_object))
> -		return PTR_ERR(gem_object);
> -
> -	args->size = gem_object->size;
> -	args->pitch = pitch;
> -
> -	drm_gem_object_put(gem_object);
> -
> -	DRM_DEBUG("Created object of size %llu\n", args->size);
> -
> -	return 0;
> -}
> -
>   static struct drm_ioctl_desc vgem_ioctls[] = {
>   	DRM_IOCTL_DEF_DRV(VGEM_FENCE_ATTACH, vgem_fence_attach_ioctl, DRM_RENDER_ALLOW),
>   	DRM_IOCTL_DEF_DRV(VGEM_FENCE_SIGNAL, vgem_fence_signal_ioctl, DRM_RENDER_ALLOW),
>   };
>   
> -static int vgem_mmap(struct file *filp, struct vm_area_struct *vma)
> -{
> -	unsigned long flags = vma->vm_flags;
> -	int ret;
> -
> -	ret = drm_gem_mmap(filp, vma);
> -	if (ret)
> -		return ret;
> -
> -	/* Keep the WC mmaping set by drm_gem_mmap() but our pages
> -	 * are ordinary and not special.
> -	 */
> -	vma->vm_flags = flags | VM_DONTEXPAND | VM_DONTDUMP;
> -	return 0;
> -}
> -
> -static const struct file_operations vgem_driver_fops = {
> -	.owner		= THIS_MODULE,
> -	.open		= drm_open,
> -	.mmap		= vgem_mmap,
> -	.poll		= drm_poll,
> -	.read		= drm_read,
> -	.unlocked_ioctl = drm_ioctl,
> -	.compat_ioctl	= drm_compat_ioctl,
> -	.release	= drm_release,
> -};
> -
> -static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
> -{
> -	mutex_lock(&bo->pages_lock);
> -	if (bo->pages_pin_count++ == 0) {
> -		struct page **pages;
> -
> -		pages = drm_gem_get_pages(&bo->base);
> -		if (IS_ERR(pages)) {
> -			bo->pages_pin_count--;
> -			mutex_unlock(&bo->pages_lock);
> -			return pages;
> -		}
> -
> -		bo->pages = pages;
> -	}
> -	mutex_unlock(&bo->pages_lock);
> -
> -	return bo->pages;
> -}
> -
> -static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
> -{
> -	mutex_lock(&bo->pages_lock);
> -	if (--bo->pages_pin_count == 0) {
> -		drm_gem_put_pages(&bo->base, bo->pages, true, true);
> -		bo->pages = NULL;
> -	}
> -	mutex_unlock(&bo->pages_lock);
> -}
> -
> -static int vgem_prime_pin(struct drm_gem_object *obj)
> -{
> -	struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> -	long n_pages = obj->size >> PAGE_SHIFT;
> -	struct page **pages;
> -
> -	pages = vgem_pin_pages(bo);
> -	if (IS_ERR(pages))
> -		return PTR_ERR(pages);
> -
> -	/* Flush the object from the CPU cache so that importers can rely
> -	 * on coherent indirect access via the exported dma-address.
> -	 */
> -	drm_clflush_pages(pages, n_pages);
> -
> -	return 0;
> -}
> -
> -static void vgem_prime_unpin(struct drm_gem_object *obj)
> -{
> -	struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> -
> -	vgem_unpin_pages(bo);
> -}
> -
> -static struct sg_table *vgem_prime_get_sg_table(struct drm_gem_object *obj)
> -{
> -	struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> -
> -	return drm_prime_pages_to_sg(obj->dev, bo->pages, bo->base.size >> PAGE_SHIFT);
> -}
> -
> -static struct drm_gem_object* vgem_prime_import(struct drm_device *dev,
> -						struct dma_buf *dma_buf)
> -{
> -	struct vgem_device *vgem = container_of(dev, typeof(*vgem), drm);
> -
> -	return drm_gem_prime_import_dev(dev, dma_buf, &vgem->platform->dev);
> -}
> -
> -static struct drm_gem_object *vgem_prime_import_sg_table(struct drm_device *dev,
> -			struct dma_buf_attachment *attach, struct sg_table *sg)
> -{
> -	struct drm_vgem_gem_object *obj;
> -	int npages;
> -
> -	obj = __vgem_gem_create(dev, attach->dmabuf->size);
> -	if (IS_ERR(obj))
> -		return ERR_CAST(obj);
> -
> -	npages = PAGE_ALIGN(attach->dmabuf->size) / PAGE_SIZE;
> -
> -	obj->table = sg;
> -	obj->pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
> -	if (!obj->pages) {
> -		__vgem_gem_destroy(obj);
> -		return ERR_PTR(-ENOMEM);
> -	}
> -
> -	obj->pages_pin_count++; /* perma-pinned */
> -	drm_prime_sg_to_page_array(obj->table, obj->pages, npages);
> -	return &obj->base;
> -}
> -
> -static int vgem_prime_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
> -{
> -	struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> -	long n_pages = obj->size >> PAGE_SHIFT;
> -	struct page **pages;
> -	void *vaddr;
> -
> -	pages = vgem_pin_pages(bo);
> -	if (IS_ERR(pages))
> -		return PTR_ERR(pages);
> -
> -	vaddr = vmap(pages, n_pages, 0, pgprot_writecombine(PAGE_KERNEL));
> -	if (!vaddr)
> -		return -ENOMEM;
> -	dma_buf_map_set_vaddr(map, vaddr);
> -
> -	return 0;
> -}
> -
> -static void vgem_prime_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map)
> -{
> -	struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> -
> -	vunmap(map->vaddr);
> -	vgem_unpin_pages(bo);
> -}
> -
> -static int vgem_prime_mmap(struct drm_gem_object *obj,
> -			   struct vm_area_struct *vma)
> -{
> -	int ret;
> -
> -	if (obj->size < vma->vm_end - vma->vm_start)
> -		return -EINVAL;
> -
> -	if (!obj->filp)
> -		return -ENODEV;
> -
> -	ret = call_mmap(obj->filp, vma);
> -	if (ret)
> -		return ret;
> -
> -	vma_set_file(vma, obj->filp);
> -	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
> -	vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
> -
> -	return 0;
> -}
> -
> -static const struct drm_gem_object_funcs vgem_gem_object_funcs = {
> -	.free = vgem_gem_free_object,
> -	.pin = vgem_prime_pin,
> -	.unpin = vgem_prime_unpin,
> -	.get_sg_table = vgem_prime_get_sg_table,
> -	.vmap = vgem_prime_vmap,
> -	.vunmap = vgem_prime_vunmap,
> -	.vm_ops = &vgem_gem_vm_ops,
> -};
> +DEFINE_DRM_GEM_FOPS(vgem_driver_fops);
>   
>   static const struct drm_driver vgem_driver = {
>   	.driver_features		= DRIVER_GEM | DRIVER_RENDER,
> @@ -427,13 +159,7 @@ static const struct drm_driver vgem_driver = {
>   	.num_ioctls 			= ARRAY_SIZE(vgem_ioctls),
>   	.fops				= &vgem_driver_fops,
>   
> -	.dumb_create			= vgem_gem_dumb_create,
> -
> -	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
> -	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
> -	.gem_prime_import = vgem_prime_import,
> -	.gem_prime_import_sg_table = vgem_prime_import_sg_table,
> -	.gem_prime_mmap = vgem_prime_mmap,
> +	DRM_GEM_SHMEM_DRIVER_OPS,
>   
>   	.name	= DRIVER_NAME,
>   	.desc	= DRIVER_DESC,
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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