drm/i915: Pin backing pages for pread
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@chris-wilson.co.uk>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 73702e5..26c8bf9 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -343,7 +343,7 @@
page_length);
kunmap_atomic(vaddr);
- return ret;
+ return ret ? -EFAULT : 0;
}
static void
@@ -394,7 +394,7 @@
page_length);
kunmap(page);
- return ret;
+ return ret ? - EFAULT : 0;
}
static int
@@ -403,7 +403,6 @@
struct drm_i915_gem_pread *args,
struct drm_file *file)
{
- struct address_space *mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
char __user *user_data;
ssize_t remain;
loff_t offset;
@@ -412,7 +411,6 @@
int hit_slowpath = 0;
int prefaulted = 0;
int needs_clflush = 0;
- int release_page;
user_data = (char __user *) (uintptr_t) args->data_ptr;
remain = args->size;
@@ -433,6 +431,12 @@
}
}
+ ret = i915_gem_object_get_pages(obj);
+ if (ret)
+ return ret;
+
+ i915_gem_object_pin_pages(obj);
+
offset = args->offset;
while (remain > 0) {
@@ -448,18 +452,7 @@
if ((shmem_page_offset + page_length) > PAGE_SIZE)
page_length = PAGE_SIZE - shmem_page_offset;
- 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;
@@ -470,7 +463,6 @@
goto next_page;
hit_slowpath = 1;
- page_cache_get(page);
mutex_unlock(&dev->struct_mutex);
if (!prefaulted) {
@@ -488,16 +480,12 @@
needs_clflush);
mutex_lock(&dev->struct_mutex);
- page_cache_release(page);
+
next_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;
@@ -505,6 +493,8 @@
}
out:
+ i915_gem_object_unpin_pages(obj);
+
if (hit_slowpath) {
/* Fixup: Kill any reinstated backing storage pages */
if (obj->madv == __I915_MADV_PURGED)