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Commit dbf7bff0 authored by Daniel Vetter's avatar Daniel Vetter
Browse files

drm/i915: merge shmem_pread slow&fast-path 



With the previous rewrite, they've become essential identical.

v2: Simplify the page_do_bit17_swizzling logic as suggested by Chris
Wilson.

Tested-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
parent e244a443

drivers/gpu/drm/i915/i915_gem.c

+27 −81
Original line number Diff line number Diff line
@@ -239,66 +239,6 @@ static int i915_gem_object_needs_bit17_swizzle(struct drm_i915_gem_object *obj) 
		obj->tiling_mode != I915_TILING_NONE;

}



/**

 * This is the fast shmem pread path, which attempts to copy_from_user directly

 * from the backing pages of the object to the user's address space.  On a

 * fault, it fails so we can fall back to i915_gem_shmem_pwrite_slow().

 */

static int

i915_gem_shmem_pread_fast(struct drm_device *dev,

			  struct drm_i915_gem_object *obj,

			  struct drm_i915_gem_pread *args,

			  struct drm_file *file)

{

	struct address_space *mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;

	ssize_t remain;

	loff_t offset;

	char __user *user_data;

	int page_offset, page_length;



	user_data = (char __user *) (uintptr_t) args->data_ptr;

	remain = args->size;



	offset = args->offset;



	while (remain > 0) {

		struct page *page;

		char *vaddr;

		int ret;



		/* Operation in this page

		 *

		 * page_offset = offset within page

		 * page_length = bytes to copy for this page

		 */

		page_offset = offset_in_page(offset);

		page_length = remain;

		if ((page_offset + remain) > PAGE_SIZE)

			page_length = PAGE_SIZE - page_offset;



		page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT);

		if (IS_ERR(page))

			return PTR_ERR(page);



		vaddr = kmap_atomic(page);

		ret = __copy_to_user_inatomic(user_data,

					      vaddr + page_offset,

					      page_length);

		kunmap_atomic(vaddr);



		mark_page_accessed(page);

		page_cache_release(page);

		if (ret)

			return -EFAULT;



		remain -= page_length;

		user_data += page_length;

		offset += page_length;

	}



	return 0;

}



static inline int

__copy_to_user_swizzled(char __user *cpu_vaddr,

			const char *gpu_vaddr, int gpu_offset,
@@ -351,14 +291,8 @@ __copy_from_user_swizzled(char __user *gpu_vaddr, int gpu_offset, 
	return 0;

}



/**

 * This is the fallback shmem pread path, which allocates temporary storage

 * in kernel space to copy_to_user into outside of the struct_mutex, so we

 * can copy out of the object's backing pages while holding the struct mutex

 * and not take page faults.

 */

static int

i915_gem_shmem_pread_slow(struct drm_device *dev,

i915_gem_shmem_pread(struct drm_device *dev,

		     struct drm_i915_gem_object *obj,

		     struct drm_i915_gem_pread *args,

		     struct drm_file *file)
@@ -369,6 +303,7 @@ i915_gem_shmem_pread_slow(struct drm_device *dev, 
	loff_t offset;

	int shmem_page_offset, page_length, ret = 0;

	int obj_do_bit17_swizzling, page_do_bit17_swizzling;

	int hit_slowpath = 0;



	user_data = (char __user *) (uintptr_t) args->data_ptr;

	remain = args->size;
@@ -377,8 +312,6 @@ i915_gem_shmem_pread_slow(struct drm_device *dev, 


	offset = args->offset;



	mutex_unlock(&dev->struct_mutex);



	while (remain > 0) {

		struct page *page;

		char *vaddr;
@@ -402,6 +335,20 @@ i915_gem_shmem_pread_slow(struct drm_device *dev, 
		page_do_bit17_swizzling = obj_do_bit17_swizzling &&

			(page_to_phys(page) & (1 << 17)) != 0;



		if (!page_do_bit17_swizzling) {

			vaddr = kmap_atomic(page);

			ret = __copy_to_user_inatomic(user_data,

						      vaddr + shmem_page_offset,

						      page_length);

			kunmap_atomic(vaddr);

			if (ret == 0) 

				goto next_page;

		}



		hit_slowpath = 1;



		mutex_unlock(&dev->struct_mutex);



		vaddr = kmap(page);

		if (page_do_bit17_swizzling)

			ret = __copy_to_user_swizzled(user_data,
@@ -413,6 +360,8 @@ i915_gem_shmem_pread_slow(struct drm_device *dev, 
					     page_length);

		kunmap(page);



		mutex_lock(&dev->struct_mutex);

next_page:

		mark_page_accessed(page);

		page_cache_release(page);
@@ -427,10 +376,11 @@ i915_gem_shmem_pread_slow(struct drm_device *dev, 
	}



out:

	mutex_lock(&dev->struct_mutex);

	if (hit_slowpath) {

		/* Fixup: Kill any reinstated backing storage pages */

		if (obj->madv == __I915_MADV_PURGED)

			i915_gem_object_truncate(obj);

	}



	return ret;

}
@@ -486,11 +436,7 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data, 
	if (ret)

		goto out;



	ret = -EFAULT;

	if (!i915_gem_object_needs_bit17_swizzle(obj))

		ret = i915_gem_shmem_pread_fast(dev, obj, args, file);

	if (ret == -EFAULT)

		ret = i915_gem_shmem_pread_slow(dev, obj, args, file);

	ret = i915_gem_shmem_pread(dev, obj, args, file);



out:

	drm_gem_object_unreference(&obj->base);