[PATCH 04/13] drm/i915: merge shmem_pwrite slow&fast-path

Daniel Vetter
2011-11-06T19:13:51Z

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

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
drivers/gpu/drm/i915/i915_gem.c | 126 ++++++++++----------------------------
1 files changed, 33 insertions(+), 93 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index be1dd4f..52fc0b5 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -728,84 +728,11 @@ out_unpin_pages:
return ret;
}

-/**
- * This is the fast shmem pwrite path, which attempts to directly
- * copy_from_user into the kmapped pages backing the object.
- */
-static int
-i915_gem_shmem_pwrite_fast(struct drm_device *dev,
- struct drm_i915_gem_object *obj,
- 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;
- int page_offset, page_length;
-
- user_data = (char __user *) (uintptr_t) args->data_ptr;
- remain = args->size;
-
- offset = args->offset;
- obj->dirty = 1;
-
- 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_from_user_inatomic(vaddr + page_offset,
- user_data,
- page_length);
- kunmap_atomic(vaddr);
-
- set_page_dirty(page);
- mark_page_accessed(page);
- page_cache_release(page);
-
- /* If we get a fault while copying data, then (presumably) our
- * source page isn't available. Return the error and we'll
- * retry in the slow path.
- */
- if (ret)
- return -EFAULT;
-
- remain -= page_length;
- user_data += page_length;
- offset += page_length;
- }
-
- return 0;
-}
-
-/**
- * This is the fallback shmem pwrite path, which uses get_user_pages to pin
- * the memory and maps it using kmap_atomic for copying.
- *
- * This avoids taking mmap_sem for faulting on the user's address while the
- * struct_mutex is held.
- */
static int
-i915_gem_shmem_pwrite_slow(struct drm_device *dev,
- struct drm_i915_gem_object *obj,
- struct drm_i915_gem_pwrite *args,
- struct drm_file *file)
+i915_gem_shmem_pwrite(struct drm_device *dev,
+ struct drm_i915_gem_object *obj,
+ 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;
@@ -813,6 +740,7 @@ i915_gem_shmem_pwrite_slow(struct drm_device *dev,
char __user *user_data;
int shmem_page_offset, page_length, ret;
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;
@@ -822,8 +750,6 @@ i915_gem_shmem_pwrite_slow(struct drm_device *dev,
offset = args->offset;
obj->dirty = 1;

- mutex_unlock(&dev->struct_mutex);
-
while (remain > 0) {
struct page *page;
char *vaddr;
@@ -847,6 +773,21 @@ i915_gem_shmem_pwrite_slow(struct drm_device *dev,

page_do_bit17_swizzling = (page_to_phys(page) & (1 << 17)) == 0;

+ if (!obj_do_bit17_swizzling || !page_do_bit17_swizzling) {
+ vaddr = kmap_atomic(page);
+ ret = __copy_from_user_inatomic(vaddr + shmem_page_offset,
+ user_data,
+ page_length);
+ kunmap_atomic(vaddr);
+
+ if (ret == 0)
+ goto next_page;
+ }
+
+ hit_slowpath = 1;
+
+ mutex_unlock(&dev->struct_mutex);
+
vaddr = kmap(page);
if (obj_do_bit17_swizzling && page_do_bit17_swizzling)
ret = __copy_from_user_swizzled(vaddr, shmem_page_offset,
@@ -858,6 +799,8 @@ i915_gem_shmem_pwrite_slow(struct drm_device *dev,
page_length);
kunmap(page);

+ mutex_lock(&dev->struct_mutex);
+next_page:
set_page_dirty(page);
mark_page_accessed(page);
page_cache_release(page);
@@ -873,15 +816,16 @@ i915_gem_shmem_pwrite_slow(struct drm_device *dev,
}

out:
- mutex_lock(&dev->struct_mutex);
- /* Fixup: Kill any reinstated backing storage pages */
- if (obj->madv == __I915_MADV_PURGED)
- i915_gem_object_truncate(obj);
- /* and flush dirty cachelines in case the object isn't in the cpu write
- * domain anymore. */
- if (obj->base.write_domain != I915_GEM_DOMAIN_CPU) {
- i915_gem_clflush_object(obj);
- intel_gtt_chipset_flush();
+ if (hit_slowpath) {
+ /* Fixup: Kill any reinstated backing storage pages */
+ if (obj->madv == __I915_MADV_PURGED)
+ i915_gem_object_truncate(obj);
+ /* and flush dirty cachelines in case the object isn't in the cpu write
+ * domain anymore. */
+ if (obj->base.write_domain != I915_GEM_DOMAIN_CPU) {
+ i915_gem_clflush_object(obj);
+ intel_gtt_chipset_flush();
+ }
}

return ret;
@@ -973,11 +917,7 @@ out_unpin:
if (ret)
goto out;

- ret = -EFAULT;
- if (!i915_gem_object_needs_bit17_swizzle(obj))
- ret = i915_gem_shmem_pwrite_fast(dev, obj, args, file);
- if (ret == -EFAULT)
- ret = i915_gem_shmem_pwrite_slow(dev, obj, args, file);
+ ret = i915_gem_shmem_pwrite(dev, obj, args, file);

out:
drm_gem_object_unreference(&obj->base);
--
1.7.6.4