On Tue, 4 Sep 2012 21:02:55 +0100
Chris Wilson <chris at chris-wilson.co.uk> wrote:
> By using the recently introduced pinning of pages, we can safely drop
> the mutex in the knowledge that the pages are not going to disappear
> beneath us, and so we can simplify the code for iterating over the pages.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
> drivers/gpu/drm/i915/i915_gem.c | 37 +++++++++++++------------------------
> 1 file changed, 13 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index aa088ef..8a4eac0 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -690,7 +690,7 @@ shmem_pwrite_fast(struct page *page, int shmem_page_offset, int page_length,
> page_length);
> kunmap_atomic(vaddr);
>
> - return ret;
> + return ret ? -EFAULT : 0;
> }
>
> /* Only difference to the fast-path function is that this can handle bit17
> @@ -724,7 +724,7 @@ shmem_pwrite_slow(struct page *page, int shmem_page_offset, int page_length,
> page_do_bit17_swizzling);
> kunmap(page);
>
> - return ret;
> + return ret ? -EFAULT : 0;
> }
>
> static int
> @@ -733,7 +733,6 @@ i915_gem_shmem_pwrite(struct drm_device *dev,
> struct drm_i915_gem_pwrite *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;
> @@ -742,7 +741,6 @@ i915_gem_shmem_pwrite(struct drm_device *dev,
> int hit_slowpath = 0;
> int needs_clflush_after = 0;
> int needs_clflush_before = 0;
> - int release_page;
>
> user_data = (char __user *) (uintptr_t) args->data_ptr;
> remain = args->size;
> @@ -768,6 +766,12 @@ i915_gem_shmem_pwrite(struct drm_device *dev,
> && obj->cache_level == I915_CACHE_NONE)
> needs_clflush_before = 1;
>
> + ret = i915_gem_object_get_pages(obj);
> + if (ret)
> + return ret;
> +
> + i915_gem_object_pin_pages(obj);
> +
> offset = args->offset;
> obj->dirty = 1;
>
> @@ -793,18 +797,7 @@ i915_gem_shmem_pwrite(struct drm_device *dev,
> ((shmem_page_offset | page_length)
> & (boot_cpu_data.x86_clflush_size - 1));
>
> - if (obj->pages) {
> - page = obj->pages[offset >> PAGE_SHIFT];
> - release_page = 0;
> - } else {
> - page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT);
> - if (IS_ERR(page)) {
> - ret = PTR_ERR(page);
> - goto out;
> - }
> - release_page = 1;
> - }
> -
> + page = obj->pages[offset >> PAGE_SHIFT];
> page_do_bit17_swizzling = obj_do_bit17_swizzling &&
> (page_to_phys(page) & (1 << 17)) != 0;
>
> @@ -816,26 +809,20 @@ i915_gem_shmem_pwrite(struct drm_device *dev,
> goto next_page;
>
> hit_slowpath = 1;
> - page_cache_get(page);
> mutex_unlock(&dev->struct_mutex);
> -
> ret = shmem_pwrite_slow(page, shmem_page_offset, page_length,
> user_data, page_do_bit17_swizzling,
> partial_cacheline_write,
> needs_clflush_after);
>
> mutex_lock(&dev->struct_mutex);
> - page_cache_release(page);
> +
> next_page:
> set_page_dirty(page);
> mark_page_accessed(page);
> - if (release_page)
> - page_cache_release(page);
>
> - if (ret) {
> - ret = -EFAULT;
> + if (ret)
> goto out;
> - }
>
> remain -= page_length;
> user_data += page_length;
> @@ -843,6 +830,8 @@ next_page:
> }
>
> out:
> + i915_gem_object_unpin_pages(obj);
> +
> if (hit_slowpath) {
> /* Fixup: Kill any reinstated backing storage pages */
> if (obj->madv == __I915_MADV_PURGED)
I'll leave the pread/pwrite reviewing to Daniel...
--
Jesse Barnes, Intel Open Source Technology Center
