On 05/04/16 13:57, Chris Wilson wrote:
If we want a contiguous mapping of a single page sized object, we can
forgo using vmap() and just use a regular kmap(). Note that this is only
suitable if the desired pgprot_t is comptabitible.
You noticed the spelling already. :)
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_gem.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 985f067c1f0e..dc8e1b76c896 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2233,7 +2233,10 @@ i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
list_del(&obj->global_list);
if (obj->vmapping) {
- vunmap(obj->vmapping);
+ if (obj->base.size == PAGE_SIZE)
+ kunmap(kmap_to_page(obj->vmapping));
+ else
+ vunmap(obj->vmapping);
Can't think of a reason why it would be better but there is also
is_vmalloc_addr(addr) as used by kvfree.
obj->vmapping = NULL;
}
@@ -2416,15 +2419,22 @@ void *i915_gem_object_pin_vmap(struct drm_i915_gem_object *obj)
i915_gem_object_pin_pages(obj);
if (obj->vmapping == NULL) {
- struct sg_page_iter sg_iter;
struct page **pages;
- int n;
- n = obj->base.size >> PAGE_SHIFT;
- pages = drm_malloc_gfp(n, sizeof(*pages), GFP_TEMPORARY);
+ pages = NULL;
+ if (obj->base.size == PAGE_SIZE)
+ obj->vmapping = kmap(sg_page(obj->pages->sgl));
+ else
+ pages = drm_malloc_gfp(obj->base.size >> PAGE_SHIFT,
+ sizeof(*pages),
+ GFP_TEMPORARY);
if (pages != NULL) {
+ struct sg_page_iter sg_iter;
+ int n;
+
n = 0;
- for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, 0)
+ for_each_sg_page(obj->pages->sgl, &sg_iter,
+ obj->pages->nents, 0)
pages[n++] = sg_page_iter_page(&sg_iter);
obj->vmapping = vmap(pages, n, 0, PAGE_KERNEL);
Two problems I can spot are:
1. Callers of pin_vmap now don't know which kind of address they are
getting. Maybe call it pin_kvmap or something? Just mention in kerneldoc
could be enough.
2. Shrinker will try to kick out kmapped objects because they have
obj->vmapping set.
Regards,
Tvrtko
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